Higher Boost Pulleys and Stock Miata Ignitions

[lowboy72]

So this post is to share a discovery that I have had about my 2002 Miata ignition system. I am sure everyone here who has gone to a 115mm pulley or better have attempted to tackle the issue of how to get a better, more efficient spark to go along with that extra boost. I personally have had issues with what I thought was fueling. I was leaning out top end with the 130mm pulley, so bad in fact that I put the 115mm one back on the car. Much to my dismay, the same thing was happening with the 115mm, but later in the RPM band. Also I noticed that the 115mm pulley pulled significantly harder top end than the 130mm.

I spoke with Tom a few weeks ago about it and he mentioned that it might have something to do with what he recently discovered about the stock ignition spark. So I started actually searching for ignition boosters and inadvertently came across this website: http://www.pulstar.com/. They have a plug with what is in essence a built in capacitor to store and release a shorter more powerful spark. They are expensive, but I was in the mood to experiment.

So I bought them and installed them, carefully. I went out for a test drive and watched my AFR. With my NGK Iridium plugs my AFR at 6500 RPM would be 11.3 by 6500 RPM and would lean out up to 12.7 to 1 at redline. With the Pulstar plugs the AFR dropped in a linear fashion and was 10.4 to 1 at redline. So this told me in effect that my problem was spark, not fuel pressure I as orignally thought. Now that I am combusting the fuel more efficiently I can reduced the addition to the pulse width. With that the power increase top end improved dramatically and I am looking forward to re-installing my 130mm pulley.

So anyone here that is doing 13lbs or more of boost and have not addressed their ignition system probably should give it some serious thought. I just wanted to share what worked for me and open up a discussion about these plugs and other ignition options.

[tann3r]

Did you make any adjustments to the fueling?

If fueling was not changed, I'd expect a decrease in AFR to indicate incomplete combustion. this assumes that the only thing you changed was the spark plugs.

Whats your setup? I'm running a 115/65 ffs coldside and do not have a problem with high rpm AFR.

[Tom @ Fast Forward]

Colin,

That is the error most people make because it is logical. :) However, the Wideband A/F gauge is really only an O2 sensor reading excess O2. When you have a weak spark, you don't burn the fuel and that makes it go richer and richer. However, you also increase the unburned O2. As the sensor is sees the excess O2 as a lean condition, and displays it as such, you add fuel. Then you get the spark corrected, as James just did, and burn more of the O2 and the gauge thinks you are now rich as it see less O2 so you have to reduce fuel to get the desired reading. Misfires show up the same way. You would think a misfire would show rich as the fuel didn't burn but it shows lean because the O2 didn't burn either.

I may try a set of these plugs as well but want to take some readings first. And, if I do swap the plugs, I'll do it at the dyno with before and after runs. I am also looking at ways to enhance the stock ignition/coils and aftermarket ignition like AEM, Mallory and MSD. At the moment, the AEM looks the best to me for aftermarket. These plugs, for $100, might be the answer to a maidens prayer as well.

One might suppose that as long as the plugs spark, what else matters. However, the quality of the spark is important. It should be a nice white spark. I used to have that when I had the SplitFire COPs. Then one of the igniters died and I found that they no longer make them for the Miata. I installed new Miata coils and, even at idle, the spark is blue, not white. Take a spare sparkplug, stick it in one of the sparkplug wires and lay it carefully where the metal body of the plug touches the engine and start the engine. Don't let it run too long as it is running on three cylinders and the other one is getting fuel. If it is bright white, you are good to go.

I also think there is a possibility, some of the cars have a bad/weak ground for the ignition connection or dirty connectors for the 12VDC lead to the coils. Either case can cause the same problem, weak spark. Sparks enough to run a NA engine or a boosted engine up to some level of boost but, beyond that, WHP loss. You can see it on a dyno graph as it will draw a beautiful straight line up to some HP or boost point and then just start to roll off. The stock Miata coils are weak at best and worse as they age. Think of it this way when it comes to the 12V and GND connections: If 14V gets 24,000 Volts at the plug, every volt that drops is worth about 1700V at the plug and you need every volt you can get as pressure (boost) increases. The norm for boosted engines is to reduce sparkplug gap about .003" per 50HP increase. we should be dropping the stock gap from 0.044" to maybe 0.038" but find we need to get down around 0.030-0.032" to make it run right at the top. The reason is simple, insufficient spark. There is one there, just not hot enough.

James might have just found a $100 solution.

[Tom @ Fast Forward]

I should add that if you think you can install them and gain 10WHP, for example, the answer is yes and no. If you dyno your Coldside and the line is straight all the way to redline, you probably wont gain 1 WHP. It is one of those "It depends on the circumstances" parts.

We tested a header that claimed 10WHP gain. Well, on a stock engine, I have no doubt it would get close to that. It was designed to scavenge the exhaust and help pull the spent air/fuel out of the cylinder to make way for new air and fuel. On a Coldside engine, and 99+car, it had 0 effect as the blower is already pushing the spent gas out and the header only needs to get out of the way. On the older engines with restrictive exhausts, it would still probably help.

The need for better ignition is the same. If the old ignition is already doing the job, these plugs or CD ignition or whatever device you find to enhance the ignition, isn't going to do a whit for performance. Just wanted to clear that up before somebody with 5 PSI boost or normall aspirated popped in to say they tried them and they did nothing. If you have tire that you can't spin now and work great in the turns, putting better tires on wont help either. BUT, if you install a 225WHP Coldside, those oversized, stickier tires would be a welcome addition. :)

[lowboy72]

An inefficient burn will also cause higher EGTs. I seen about a 200-300 degree drop in my max EGT temp once I switched over.

As Tom says they need to be thoroughly tested. My concern right now is the insulator and whether I am pulling enough heat out of the combustion chamber. I left the gap kind of wide and I will be monitoring the plugs closely for any indication that they are running too hot.

Personally I think my long term solution will be an aftermarket ignition system. But it seems right now that the plugs are a quick solution to my ignition problem.

[Tom @ Fast Forward]

James,

Well, after several back and forths with SparkPlugs.com, I have a set on the way. I will try and set up for Thursday on the dyno for before and after.

I also chatted with them about fragility. The feeling is that if you are reasonably competent at changing plugs, that is not any more of a problem than regular plugs. If not, you should find someone who is competent. :)

After the conversation with you and the specs on their website and the conversation with them via email and by phone today, I have high expectations for these to be as good as going the Toyota COP route.

More to follow after the dyno. It's only money. It's only money. It's only money. It's........

[Satisaii]

I can't wait for the results. I've heard some mixed reviews from some online users, but I know that you will be a bit more scientific with your findings.

[Tom @ Fast Forward]

My 99 made 222 with a 125mm pulley and SplitFire COP setup (I wish they still made them). My HP has been down since I replaced the COPs with stock coils. I can't wait to get it back. Good stock coils seem to be able to support up to 115mm pulleys. After that, you keep increasing all that low end torque but actually go down in top end WHP. I didn't mind as the extra torque is a lot of fun but, I wouldn't mind having my cake and eating it too. :)

If they don't do the trick, it's off to CDI testing.

[pat conlon]

Meee tinks you'se ment 222 ;-)
My Splitfire COP's are still sparking fine (knock on wood) Per your experience I got a spare Splitfire igniter...
Pat (still waiting for the TVS)
My 99 made 122 with a 125mm pulley and SplitFire COP setup (I wish they still made them).

[Tom @ Fast Forward]

Isn't that what I said? It 'pays' to own the forums once in awhile. :)

Good catch. I d o that frequently. Worst was went I sent an email to a potential customer talking about the 230mm pulley I was running. Needless to say, he was impressed that I could run such a BIG pulley. ;)

[socal pat]

I am looking forward to going from my 115mm pulley to a 125, but this thread has me waiting to see what these plugs will do for us first. Man, for $100 and more power...sign me up.

[lowboy72]

Once I get a halfway decent day of weather I am going to put back on the 130mm pulley and see how it works out. I am pretty excited at the prospect. The only thing for me is my car is only five years old and I wonder why such a significant degradation in the quality of the spark. It has to be wiring because the coilpacks and the plug wires are brand new. This spring I plan on going over the wiring with a fine tooth comb and see if I can find something suspect.

[Satisaii]

I would also like for you to get Ari's car with his Toyota COP setup over there for some testing. If his is working right, then I might try it.

[Tom @ Fast Forward]

Pat, I can hardly wait till next week either.

James, not necessarily degraded. Just not up to snuff to begin with for that big pulley. I think Miata coils/ignition is just short on quality of spark.

Jim, a little late for before and after on Ari's COP I'm afraid.

[Satisaii]

I am just curious to see if it is working as well as it should. The dyno might show something that you can't feel driving around.

[Tom @ Fast Forward]

I agree. I would love to see it as well but, without a before, the after doesn't tell you what happened. We have 'before' from awhile back but he has done several things inbetween.

[Satisaii]

He went for a plug and play setup, right? It should be easy to switch back and forth...

Considering that I am not doing anything with mine for the next couple of months, I might give this a shot. My budget has been slashed dramatically, but I think I can swing it over a couple of months.

[99mx5]

Yeah, The COPS are easy to remove and the original coils do not need to be installed for a dyno test. They could just rest on top of the engine while on the dyno.

[Tom @ Fast Forward]

Cool. Something we can do then.

[Tom @ Fast Forward]

That was quick. I just got 5 of the new spark plugs in the mail. I am set for 9:00 AM Thursday for test and tune. I expect to post results here by Thursday night. I don't have a dog in this fight so the results will simply be the results but I HOPE they work as it would be a cheap way out.

[tann3r]

Awesome, I look forward to seeing the results. Any chance you can throw some copper V-Powers in there for the other end of the spectrum?

[Tom @ Fast Forward]

Actually, copper V-Power is what is in there at the moment, I think. BKR7E, I think. Last time we were trying to resolve the ignition problems Keith said he wanted to try them and I picked up a set and we put them in. No change so we left them in. I will comnfirm when we take them out.

That brings up a good point. These BE-1 plugs have a center electrode that looks awfully familiar to the Iridium plugs we ship with the kits.

[Tom @ Fast Forward]

Just found this on their website. This could be a problem. I just wrote them and asked what heat range these are. Will let you know. :(

Can I use pulse plugs in an altered or modified engine?

No. Pulstar model recommendations are for stock, unmodified engines. If you have added an aftermarket turbocharger, supercharger, nitrous or any other product that increases displacement or compression to your engine you will require a colder heat range in order to avoid possible damage to your engine. Pulstar plugs only come in one heat range which will not likely be cold enough depending on what modifications you have installed.

[Tom @ Fast Forward]

Whew, it is basically the same as heat range 7. It should work just fine. Probably work fine on the 01-05 as well.

[BlownMX5]

Whew, it is basically the same as heat range 7. It should work just fine. Probably work fine on the 01-05 as well.

So they're colder than stock then?

[Tom @ Fast Forward]

Normal plugs are either HR 5 or 6. We ship 7 (94-00) or 8 (01-05). If these work as hoped for, 7 would probably be good enough for the 01-05 as well.

[Tom @ Fast Forward]

Normal plugs are either HR 5 or 6. We ship 7 (94-00) or 8 (01-05). If these work as hoped for, 7 would probably be good enough for the 01-05 as well. James (Lowboy72) is running a 2002, I believe.

[lowboy72]

It is good to hear that the plugs are a heat range 7 plug. I do see a bit of EGT increase in 4k+ RPM driving, more than I did with the other plugs. It is not enough to really be concerned about though.

[Tom @ Fast Forward]

Well, even though it showed 12:1 before, it was actually running pretty rich. Now, you are burning more O2 and running leaner at still 12:1. Both of those together will make more heat. The good news is that heat = power.

[Elphaba]

Sorry I couldnt make it today Tom. What did you find out at the dyno?

[Tom @ Fast Forward]

Have you ever heard the phrase "Other than that, Mrs. Lincoln, how was the play?"? Well, that pretty well sums up yesterday. ;)

As soon as my computer is done with the full mirror backup, I will write a full report. As is, I am on the PDA. After yesterday, I thought I should take a pre-emptive strike on the hard drive before it takes a shot at me too. ;)

[Tom @ Fast Forward]

Well, my computer is safely backed up so here is yesterday's tale.

We made three pulls on the dyno with the normal plugs and then installed the Pulstar plugs as gently as we could using a socket without rubber insert as suggested in the accompaning instructions and made three runs again. The stock plugs were BKR7E gapped at 0.025". The Pulstar plugs were left at the gap as delivered, ~0.045". The three runs produced the same WHP but, at the larger gap, that was impressive. However, after the third pull, it idled very poorly and we sourced the problem to #1 cylinder not firing. Inspection showed the ceramic to be broken inside the body (See photo attached). When we removed the plug, we also found the tip ceramic to be fractured. That part really worried me as that piece could have fallen off and destroyed the engine (more on that in a minute :-(). The sparkplugs showed severe bluing on the ground electrode and very white on the ceramic so they were definitely running VERY hot. We replaced the #1 sparkplug with the spare I bought and gapped all of them down to 0.035" to see if that would help under the high boost. We made three additional runs and, with no improvement, ended the project.

I then drove around to one of the open bays so we could put the normal plugs back in as I didn't trust getting ceramic pieces in my engine. All runs were at 11:1 or richer A/F, so there was no shortage of fuel. The chart they sent me shows that they are rated 5, 6 or 7 for heat range. In this test, they have all of the appearance of a 5. Way too hot. The #1 broken plug is dark color but that is from not firing after it broke.

When I left, I got about 100 yards from the shop and the engine started making noises. By the time I noticed zero oil pressure, the engine was gone. :-( Oil pressure was diligently monitored while on the dyno and was fine. My guess is that old age set in to the oil pump and death was painless and relatively instantaneous. However, it had a wonderful life and 150,000+ miles, 120,000+ of which were at 12PSI to 18PSI non-intercooled and well above double the stock WHP. The engine was bone stock and the only maintenance was oil/filter changes and a new timing belt and water pump at 60K. I finally have an excuse to build an engine. Trust me, it had nothing to do with the plugs, strictly a coincidence but thought I should explain. As soon as we get the new yoyo to market, Robello sounds like a plan.

[Tom @ Fast Forward]

Ah yes, conclusions........

I think they are fragile at the moment. Could be that the high boost I am running was too much for them? Their FAQ recommends against them for boosted applications. However, their dyno section has one of the three applications as a factory turbo. They look closer to a 5 than a 7 for heat range and that is definitely not good for a boosted Miata engine.

James, have you pulled them to look at color on your car?

[BlownMX5]

Wow, Tom... sorry to hear about your motor. Regardless of the reason it failed, it is still sad, especially since it was very much a pioneer in the FFS saga. Tear in my eye... (we need a crying smilie)

Also sorry that these plugs didn't perform as we all had hoped. But, if it sounds too good to be true... and so on.

Pat.

[Tom @ Fast Forward]

Well, I tried to keep it bone stock for the sake of science. :) Now I can do it my way for the sake of pure power. Robello definitely for the head but all I want for the block is stock Mazda pistons at 9:1 compression. I can finally get back to a stock valve cover and stock cam gears. Anybody want an adjustable cam gear. I destroyed my cam cover for the sake of scienc with that one only to discover that MAYBE 3WHP could be had under supercharger boost.

[Elphaba]

:svengo:UGH! Now Im glad I wasnt their to see it...:svengo: That just blows Tom. Sorry to here it.:no:

[dazooom]

Sorry to hear that TOM. You certainly got your money's worth out of that engine, for sure. Like you say...Now you can build an engine. I was eagerly awaiting the results as many others were. At least you were able to verify the results of the plugs. That's a blessing to the rest of us.

After already having to replace my engine, I pretty much stay clear of dyno's now. I'm happy with the way my H/S performs with the 130 pully. Even though you blew the engine shortly after the dyno runs, that oil pump was obviously ready to die. The dyno may have hastened it's death. At least you were close to home and not hundreds of miles away.

[Tom @ Fast Forward]

It ran long enough for me to get back to the dyno shop before it completely seized.

I wouldn't doubt, if we added up all the dyno runs, that it has several hundred miles testing 'stuff'. Over the years and dyno pulls, it has had a lot of knock under some of the tests. As Keith has said on NUMEROUS ocassions, if that was a Mustang, the engine would be done already. Their main business is Fords and GM products. Miata engines were born to be punished. I can't count how many times I have handed the keys to people at different events (like Deal's Gap) and said 'drive it like you stole it' and I know they have. Like the instructors over at Bondurant when I wanted to test new things like tires, suspension or bigger pulleys. Those guys only know ONE way to drive. :) At least Ashley (James at BRP named her that) gave her life for science.

[Steve in VC]

Tom,

Sorry to hear about your engine, I bet you got more smiles per mile than most (and grimaces from a fair number of hot Mustangs).

Having proved your system (with tons of safety margin - thank you very much), we all wait to see what engine you come up with.

Any thought of running the 2001+ with variable valves (with oversized valves of course), or moving the rev limiter up higher? Doesn't the 2001+ have coil on plug?

[Satisaii]

Congrats on getting to build a new one, the right way. Wish I could have done it, but I have a Chinese budget master watching my every move.

I think I will skip the plugs and go for the COP conversion.

[MX-Drew]

Sorry to read the news about the sad demise of the engine but I for one know you will build an even better engine.

At least I'm one of the lucky many who got to drive the car and not for just a day and drive it hard I did (when I could). That engine sold the FFS to me :party:

Maybe I can "pop" over when you have the new engine in so we can go for a drive. :driving:

[tann3r]

Sorry to hear about the motor Tom. Maybe you can write off the new one as a business expense. :)

Cant wait to see what you are going to put together!

[socal pat]

A stint at Robello could be interesting..... More flow less boost ;) Just FYI JE pistons are about the same cost as OEM, have no cold-piston slap and burn no oil.

[lowboy72]

Ah yes, conclusions........

I think they are fragile at the moment. Could be that the high boost I am running was too much for them? Their FAQ recommends against them for boosted applications. However, their dyno section has one of the three applications as a factory turbo. They look closer to a 5 than a 7 for heat range and that is definitely not good for a boosted Miata engine.

James, have you pulled them to look at color on your car?

Wow, sorry to hear about the engine. I actually am pulling them this weekend to check them out. I think that since I am on the 115mm pulley at the moment that I have been pretty safe. That in addition to the freezer temperatures and the fact that I recently plumbed my water injection kit back into my manifold from the original fear of lean fuel. But I guess the increase in cruising EGTs was actually more of a concern that I previously thought. To err on the side of caution I ordered a twin fire from the local speed shop once I seen the increase in EGTs. I am going to pick it up today. I do not plan on going back to a 130mm pulley until I have that installed.

Also Tom I wanted to let you know that when I spoke with the tuner guy at the shop; he said he installed a twin fire on his heavily modded S2000. He was running 1000cc injectors. He told me the twin fire helped maintain his idle by burning more fuel through the method of firing the plug multiple times during the intake stroke. It may help with people who want a somewhat larger injector but do not have a method of adjusting the ECU scaling. He said his only problem with the kit was heat. He put it in an uncirculated air location and burned the unit up. He did tell me though that AEM addressed the problem and all the newly shipped units are not nearly as sensitive.

Also I want to re-iterate that I personally am up for a bit of experimenting because I already rebuilt my engine. I am running a 2002 Miata with a head heavily ported and a 8.6 to 1 bottom end with balanced crank and carillo h beam rods. As a note I purposefully ported the head to compensate for the decrease in compression on the engine. I feared that with the 2002 I may have some issues with a rich idle possibly throwing codes and preventing me from passing emissions in VA. Happily I passed in December and have had no codes in reference specifically to the lowered compression. I also have a six speed transmission (swapped tranny and diff so I maintain the stock six speed ratio) as well so my 4th gear pulls are not nearly as long as those on a 5 speed.

[Tom @ Fast Forward]

When I get it back together, it will be available for any and all to drive. With the JIC suspension, RB sways and a engine that flows air, it should be a hoot.

James, that AEM Twin Fire has moved to the top of my list as well. That and four "pencil" coils and I think it will be a winner. I am curious as to what you see when you pull those plugs. If I recall, they say it can be programmed to fire up to 10 times each ignition cycle. That could be a real asset but personally, I'd settle for one good strong pulse.

If I remember, you also stayed with Mazda pistons? I have heard, as Pat stated, that the JE pistons wont consume oil like the Wiseco pistons do. They would be the only thing that might drag me away from Mazda pistons.

The new engine will be a full write-off. That helps. :)

[lowboy72]

When I get it back together, it will be available for any and all to drive. With the JIC suspension, RB sways and a engine that flows air, it should be a hoot.

James, that AEM Twin Fire has moved to the top of my list as well. That and four "pencil" coils and I think it will be a winner. I am curious as to what you see when you pull those plugs. If I recall, they say it can be programmed to fire up to 10 times each ignition cycle. That could be a real asset but personally, I'd settle for one good strong pulse.

If I remember, you also stayed with Mazda pistons? I have heard, as Pat stated, that the JE pistons wont consume oil like the Wiseco pistons do. They would be the only thing that might drag me away from Mazda pistons.

The new engine will be a full write-off. That helps. :)

The guy that spec'd and built my engine used the wiseco +1 8.6 to 1 pistons. I have about 5000 miles on the car with no noticable oil comsumption. This guy is very popular in the DC Metro area for building spec race engines and did not come cheap. The block labor alone was close to 3000 dollars.

[Tom @ Fast Forward]

When I built that other engine a couple years back, I had about $7500 in it. Carillo rods and Wiseco pistons and professionally done. I swear the engine could do the 24 hours of LeMans and not burn a drop of oil. However, put it on the Interstate and set the cruise for 75 where the pistons could run nice and cool, and it could consume 1/2 quart per tank. I know of two engines built by FM that did the same. When the owner got the first replaced with the second, he was relieved that it only burned a quart in 500 miles. I don't think the pistons are a weak spot in the Miata engine even at 18PSI. Even the stock rods, if you are staying with the stock rev limit, are probably fine at our power levels. My latest history seems to make me think the oil pump might be the weak link. :) Maybe the new engine should get the billet oil pump? ;)

[lowboy72]

When I built that other engine a couple years back, I had about $7500 in it. Carillo rods and Wiseco pistons and professionally done. I swear the engine could do the 24 hours of LeMans and not burn a drop of oil. However, put it on the Interstate and set the cruise for 75 where the pistons could run nice and cool, and it could consume 1/2 quart per tank. I know of two engines built by FM that did the same. When the owner got the first replaced with the second, he was relieved that it only burned a quart in 500 miles. I don't think the pistons are a weak spot in the Miata engine even at 18PSI. Even the stock rods, if you are staying with the stock rev limit, are probably fine at our power levels. My latest history seems to make me think the oil pump might be the weak link. :) Maybe the new engine should get the billet oil pump? ;)

Wow, I am not sure why my car doesn't burn oil then. Of those 5000 miles, 4000 has been highway of which including trips that were 250 miles or more one way. I maintain a speed between 70 to 75 miles an hour for very long stretches on those trips. I regularly check the oil for fear of consumption and just have not seen it.

I actually went with stiffer valve springs, new rods and pistons to give me the flexibility to possibly increase my rev limit in the future (I was told it could handle up to 8k). I am sure you guessed by now I am addicted to tinkering and I wanted to leave my options open.

[Tom @ Fast Forward]

When I did that other engine, I did the oversized valves and heavier springs and titanium keepers so I could also raise the rev limiter. Then I did the rev limiter package from Florida. It is the one where they swap the crystal ( I have some here if you want one). That works but, at the time, appeared to screw up off boost fuel.

Next you are going to want to go stand alone even after I gave you the keys to PC-Pro heaven. ;)

[lowboy72]

I pulled the pulstar plugs today and they looked fine. I wired in the twin fire but I still need to get the pencil coils (they should arrive this week). I hope that the stock trigger signal will fire the twin fire or I may be investing in that ECU a little early.

[Tom @ Fast Forward]

My hero. I can hardly wait for results. Especially with the 130mm pulley. The Twin Fire is what I have in mind, unless something better comes along, for the new engine.

The stock ECU signal should be fine. Is the dwell adjustable on the Twin Fire? Or, if it is fixed, what is it?

[lowboy72]

My hero. I can hardly wait for results. Especially with the 130mm pulley. The Twin Fire is what I have in mind, unless something better comes along, for the new engine.

The stock ECU signal should be fine. Is the dwell adjustable on the Twin Fire? Or, if it is fixed, what is it?

You basically have two options, trigger on the rising edge or trigger on the falling edge. This is right from the manual:

Switch 2 Trigger Edge – S2 sets the input trigger edge that the Twin Fire uses to trigger the spark plug
firing. Rising edge (S2 - Off - Default) is used when the Twin Fire is wired in AFTER the ignitor (Ignition
Amplifier) or if the ignition did not have an external ignitor and there is not one inside the coils. Falling edge (S2
– On) is used when the Twin Fire is wired directly to the ECU and the Ignition trigger is a digital signal with high
signifying dwell time.

[Tom @ Fast Forward]

You want S2-On as the ECU and Timing card are delaying for Retard. But there is nothing about dwell? Humm. I would think they would allow for different cars? Maybe it doesn't matter as they simply keep firing?

[Elphaba]

:confused: Any way to put COPs on a 1.6 system?

[Tom @ Fast Forward]

I don't know if these would work for sure but I think so.

When could we get together down here for me to run the oscilloscope on your 1.6L?

[Elphaba]

lemee look at next weeks schedule. Ill get back.

[Tom @ Fast Forward]

Great. Ari needs pictures for the 90-93 Hotside CAI too. :)

[Elphaba]

:svengo:DOH! Forgot to do that last time...:gnorsi:

[Tom @ Fast Forward]

AZ summer is on it's way.

[Satisaii]

After reading the "blown fuse" thread on the AEM forums, I am no longer sure I want to try the Twin Fire. I think I will wire it such that I can easily swap back to stock on the side of the road.

Is there a good source for automotive grade wire connectors?

[BlownMX5]

Is there a good source for automotive grade wire connectors?

McMaster-Carr? (http://www.mcmaster.com) Look under "Lighting and Electrical".

Pat.

[lowboy72]

After reading the "blown fuse" thread on the AEM forums, I am no longer sure I want to try the Twin Fire. I think I will wire it such that I can easily swap back to stock on the side of the road.

Is there a good source for automotive grade wire connectors?

I am sure that they have had one or two hardware revisions since that thread was started. I will be carrying the loopback plug and the stock coils with me in case I do run into a problem and need to bypass the unit. The benefits definitely outweigh the risks in this regard.

[Tom @ Fast Forward]

More spark power requires more feed power. They may require a larger fuse and beefier wire back to the fuse box. The stock Miata wire feed and connectors for the ignition is somewhat meek and humble.

[Satisaii]

They are supposed to have a wire run directly to the battery for the power. This wire gets a 15 amp fuse.

The story goes like this:

After x minutes/hours/days/months/miles/kilometers the 15 amp fuse blows. Once this fuse blows, it will then always blow at key on. The solution is to return the Twin Fire to AEM for warranty work that generally takes MONTHS to complete. People have found that threats of lawsuits or asking for a refund might speed this up. On this 6 page thread, there is not a single response from an AEM represenitive. The most recent one is still waiting for his unit as of January 19.

From the serial numbers listed, they may have sold 1000 of them now (a WAG). If that is true, I would also guess that 1% of the owners have reported a problem on that forum. Not a good failure rate.

[lowboy72]

The forum thread was for the fuse to the direct 12volt feed to the twin fire. A component failure in the twin fire caused the problem and the unit was replaced. I used a 10 AWG cable with added insulation from the battery to the unit. The actual 540 volt wires are connected directly to the coil by the harness provided. For my car the ground wire used off the coil is 16 AWG and does not share a ground. So the unit itself is completely isolated from the electronics and power for any other component. The only real concern is how adequate are the ground straps off of the block. I will be adding a another ground strap from the valve cover to the passenger side frame rail just to be certain.

[Tom @ Fast Forward]

AutoZone sells some nice ground straps for only a couple bucks. I added one to the driver's side of the engine a year or so ago when I was having problems with the starter. Helped a lot. I went from the lift eye bolt to the chassis. Miata ground from the block seems marginal at best.

[ThomS]

AutoZone sells some nice ground straps for only a couple bucks. I added one to the driver's side of the engine a year or so ago when I was having problems with the starter. Helped a lot. I went from the lift eye bolt to the chassis. Miata ground from the block seems marginal at best.

Is this something that most of us should look into or is a isolated problem?

[Tom @ Fast Forward]

It's one of those $6 things that takes 5 minutes to install and doesn't hurt. Is it needed? I really don't know. But it sure helped my 99 start again. I think it can't hurt the ignition either as it gets it's ground from the block.

[Satisaii]

I have the Twin Fire and coils. I need to put in a call to AEM to find out exactly how to wire in the coils (series vs parallel.) Depending on how busy I am tomorrow, I might be able to get it running.

[lowboy72]

I have the Twin Fire and coils. I need to put in a call to AEM to find out exactly how to wire in the coils (series vs parallel.) Depending on how busy I am tomorrow, I might be able to get it running.


The instructions show the wiring for a two Coil ignitor setup. Since the Miata still has to fire wasted spark anyways (only two triggers) I am going to wire mine so that the brown wire for coil one goes to pencil coils one and four and the orange wire for coil two goes to pencil coils two and three. If you look at the four coil setup, tan and pink are spliced but they will need to go to one/four two/three instead of 1/3 and 2/4 in the diagram.

If AEM tells you otherwise I would be curious to know. I will be wiring mine in this weekend on a 2002.

[Tom @ Fast Forward]

Boy am I glad I have 6-8 weeks for you guys to figure it out. ;)

[Satisaii]

This is the way I am going to hook it up:

Brown to - Coil 1
Tan to + Coil 4
Jumper + Coil 1 to - Coil 4

Orange to - Coil 2
Pink to + Coil 3
Jumper + Coil 2 to -Coil 3

Set unit to wasted spark. And watch for things blowing up.

Does the Miata ECU provide a ground trigger or a positive trigger? I don't have the tools to figure this out.

[lowboy72]

This is the way I am going to hook it up:

Brown to - Coil 1
Tan to + Coil 4
Jumper + Coil 1 to - Coil 4

Orange to - Coil 2
Pink to + Coil 3
Jumper + Coil 2 to -Coil 3

Set unit to wasted spark. And watch for things blowing up.

Does the Miata ECU provide a ground trigger or a positive trigger? I don't have the tools to figure this out.


So you are going with a serial wiring method. Is this what AEM recommended?

[Satisaii]

Page 16 of the instructions seems to be the closest to what is going on with the Miata ignition, ie a pair of COPs fired off of one input signal wire. Nowhere in the instruction booklet do they show 2 coils hooked to the same trigger (-) wire. I would be more tempted to hook the one Miata signal lead to two of the inputs on the AEM box than run the coils in parallel at this point. I should have it ready to try tomorrow, if nothing else interferes.

[Satisaii]

Life interfered. I doubt that I will get back to the Miata before next weekend.

[lowboy72]

I wired in the pencil coils and the twin fire over the weekend. Sad to say though I am having a problem that is most likely not related to the wiring but possibly a bad unit. When I attempt to crank the engine the electrical system in the car completely shuts down after 3-5 crank cycles, everything resets and will crank again. I have checked and double checked the wiring. I am not shorting out any stock component either so there are no blown fuses to indicate a problem. The battery is at 11.95 volts cold and 14.9 volts running so no problem with the alternator or battery itself. I have tested the plugs and coils through the twin fire by grounding the trigger and all four coils fire. I am at a total loss as to the problem and I will be calling AEM this morning to see if they can help.

I did get it running right one time so I know it is possible. The car had the 115mm pulley on at the time and there was a noticible increase in torque. I am really looking forward to getting this resolved.

[Satisaii]

Finished hooking mine up today. It starts and idles, but I have not driven it any. Idle quality seems to be the same.

[Tom @ Fast Forward]

I'm sure James will be interested in your wiring diagram. He is having a hard time with his and is thinking it is a defective one.

[Satisaii]

I wired it with the coils in serial, per page 16 of the instruction manual.

I still need to drive it. I think I have only put about 60 miles on it this year. No motivation to go out and drive right now.

[Tom @ Fast Forward]

Science and the greater good of your fellow Miatafiles? ;)


No motivation to go out and drive right now.

[Satisaii]

I drove it around the block, let it idle for a while, and then drove it around the block again.

So it does drive. I did floor it once, but could not tell anything (it only has 60 miles since the rebuild, so no belt on the the SC.)

I am coming to the conclusion that I just don't live in the right place to have a heavily modified car. It is at least 10 minutes (on a good day) in stop and go traffic to get on a freeway from here, so all I really can do is tootle around the neighborhood (easily.) I am thinking about selling it, so if you are interested in a car with some interesting parts and work done to it... and I don't like messing with these things, so it will be cheap. The caveat will be that you would have to take ALL of my Miata related parts.

[bogey]

I am coming to the conclusion that I just don't live in the right place to have a heavily modified car. It is at least 10 minutes (on a good day) in stop and go traffic to get on a freeway from here, so all I really can do is tootle around the neighborhood (easily.) I am thinking about selling it, so if you are interested in a car with some interesting parts and work done to it... and I don't like messing with these things, so it will be cheap. The caveat will be that you would have to take ALL of my Miata related parts.

It sounds like you need a vacation! Try a cross country drive, taking all the backroads. It's the ultimate experience to put the pleasure back into driving!

[lowboy72]

I drove it around the block, let it idle for a while, and then drove it around the block again.

So it does drive. I did floor it once, but could not tell anything (it only has 60 miles since the rebuild, so no belt on the the SC.)

Just out curiousity what year is your Miata? I discovered the problem with my 2002 and the twin fire. I do not have enough voltage in the stock trigger signal for the twin fire to reliably detect and fire. The minimum trigger input voltage is around 3.8 volts. My signal waveform is a rising edge signal that starts at 2 volts and peaks at 2.6 before going to 0. I spoke with AEM and they that I was lucky to even get it to start with the twin fire on the car.

[Tom @ Fast Forward]

Do both of you have the exact model AEM and same part number coils? If so, I think I will order a set to test on Bill's 99.

Please post the AEM Part numbers for me to order. Thanks.

James, did AEM say what voltage/current was needed?

[Satisaii]

30-2821
30-2850

I have a 99. I was worried about that signal.

It sounds like you need a vacation! Try a cross country drive, taking all the backroads. It's the ultimate experience to put the pleasure back into driving!

I live in the middle of LA. I went out for a drive once and stopped at a gas station right at the base of one of our local mountains. A couple of fellow Miata owners came over and warned me that there was a check point just up the road where the CHP were popping hoods looking for modifications. That was the last time I really drove this car. This car is also stripped down for the track, so it is not much fun on the streets (six puck solid disk clutch, Tein Flex, depowered rack, no heater, no interior...)

[bogey]

So I guess the nice weather makes up for living in a police state! :dupe: I could never live there...

[Race Grandpa I]

I bet you would like San Louis Obispo and adjacent areas and then there are areas N of San Francisco.

So I guess the nice weather makes up for living in a police state! :dupe: I could never live there...

[Tom @ Fast Forward]

Arizona was the last of the continental US states (#48) because God was saving the best for last. ;)

[bogey]

I agree, the Arizona roads are awesome! Especially the Coronado Trail (AZ 191) and US 60 through Salt River Canyon. Lots of Road Runner/Wiley Coyote type of roads.

[Tom @ Fast Forward]

On their way. Should be here in a couple days. $550 for igniter and 4 coils. They better work. :)


30-2821
30-2850

I have a 99. I was worried about that signal.



I live in the middle of LA. I went out for a drive once and stopped at a gas station right at the base of one of our local mountains. A couple of fellow Miata owners came over and warned me that there was a check point just up the road where the CHP were popping hoods looking for modifications. That was the last time I really drove this car. This car is also stripped down for the track, so it is not much fun on the streets (six puck solid disk clutch, Tein Flex, depowered rack, no heater, no interior...)

[Satisaii]

Excellent. Can't wait to see your results.

[Satisaii]

I am looking to do some dyno tuning on the car. I don't think I am up for the drive out to Phoenix, do you have any connections in the Glendale CA area?

[Tom @ Fast Forward]

No connections there for dyno tuning. Sorry. I'm sure we could send Bill over for a price. I am also sure we could find a dyno, just don't know any in-house tuners I have confidence in.

[BlownMX5]

No connections there for dyno tuning. Sorry. I'm sure we could send Bill over for a price. I am also sure we could find a dyno, just don't know any in-house tuners I have confidence in.

You could try going to DynoJet Research (http://www.dynojet.com/dyno_centers/list_automotive.aspx) and searching for a local shop. I've used GTR in Rancho Cucamonga before and they were fine. But there are some others that might be nearer to you.

Pat.

[Satisaii]

There are a couple on there that Google did not turn up. I guess what I am a really wanting is to get it conservatively set-up without having to do it on I5. I figure any place with a dyno will do.

[Tom @ Fast Forward]

--------------------------------------------------------------------------------

Shop Name, Address Contact Info. Model Distance

--------------------------------------------------------------------------------


Lou's Performance Telephone: 818-899-1500
12071 Bradford St. #8 Email:
Sun Valley, CA 91352 Website: Model 224x 5 miles

--------------------------------------------------------------------------------


HK Motorsports Dyno Shop Telephone: 818-908-9650
15020 Oxnard st. unit A Email: haryk2@aol.com
Van Nuys, CA 91411 Website:www.hkmotorsportsdynoshop.com/ Model 248x 9 miles

--------------------------------------------------------------------------------


Rene's Motor Sports & Mufflers Telephone: 323-221-6939
4739 Valley Blvd Email:rene@renemotorsports.com
Los Angeles, CA 90032 Website:http://www.renesmotorsport.com Model 224x 9 miles

--------------------------------------------------------------------------------


Rene's Motor Sports & Mufflers Telephone: 323-221-6939
4739 Valley Blvd Email:rene@renemotorsports.com
Los Angeles, CA 90032 Website:http://www.renesmotorsport.com Model 224x 9 miles

--------------------------------------------------------------------------------


JG Engine Dynamics Telephone: 626-281-5326
431 South Raymond Ave. Unit 2 Email:
Alhambra, CA 91803 Website:www.jgenginedynamics.com Model 248 10 miles

--------------------------------------------------------------------------------


DC Performance Telephone: 310-841-6996
3370 S. Livonia Ave. Email:
Los Angeles, CA 90034 Website:www.dcperformance.com Model 224xLC 11 miles

--------------------------------------------------------------------------------


Rodworks Inc Telephone: 310-559-3071
3745 Overland Ave Email:rodworksinc@sbcglobal.net
Los Angeles, CA 90034 Website:www.rodworksinc.com Model 224x 11 miles

--------------------------------------------------------------------------------


Dynamic Tuning Solutions Telephone:
7444 Reseda Boulevard Unit J Email:
Reseda, CA 91335 Website:www.dynamictuningsolutions.com 224xLC 14 miles

--------------------------------------------------------------------------------


Smoothlinez Telephone: 626-279-9828
9828 Alpaca St. Email:sales@smoothlinez.com
South El Monte, CA 91733 Website: www.smoothlinez.com Model 224x 16 miles

--------------------------------------------------------------------------------


Street Tuning & Dyno Telephone: 323-569-3432
4983 Firestone Blvd Email:aztlanhotrod@hotmail.com
South Gate, CA 90280 Website: Model 224x 16 miles

--------------------------------------------------------------------------------


Motor Meister Telephone: 562-401-3673
12662 Woodruff Avenue Email:
Downey, CA 90241 Website:www.motormeister.com Model 224x 18 miles

--------------------------------------------------------------------------------


SZ Telephone: 818-703-6272
10060 Canoga Ave Unit B Email: sebastian@specialtyz.com
Chatsworth, CA 91311 Website:www.specialtyz.com Model 224xLC 19 miles

--------------------------------------------------------------------------------


Muscle Motors Telephone: 818-888-7778
9016 Owensmouth Ave. Email:
Canoga Park, CA 91304 Website:www.musclemotors.com Model 224xLC 19 miles

--------------------------------------------------------------------------------


GS Motorsports Telephone: 562-777-1075
13008 Los Nietos Rd. Email: sales@gsmotorsports.com
Santa Fe, CA 90670 Website:www.gsmotorspors.com Model 424xLC2 20 miles

--------------------------------------------------------------------------------


R & D Dyno Service Telephone: 310-516-1003
115 E. Gardena Blvd. Unit 1 Email:
Gardena, CA 90248 Website: www.rddyno.com/ Model 248 20 miles

--------------------------------------------------------------------------------


SP Engineering Telephone: 626-333-5398
424 Turnbill Canyon Rd. Email:
City of Industry, CA 91744 Website:www.sp-power.com Model 248 22 miles

--------------------------------------------------------------------------------


Swanson Performance Telephone: 310-787-7800
22414 South Normandy Suite H Email:
Torrance, CA 90502 Website: www.swansonperformance.com/ Model 248 23 miles

--------------------------------------------------------------------------------


Yimi Sport Tuning Telephone: 661-251-3966
26524 Ruether Ave. Unit 510 Email: paul@yimisport.com
Santa Clarita, CA 91350 Website:www.yimisport.com/ Model 424x 23 miles

--------------------------------------------------------------------------------


H K S Telephone: 310-763-9600
2801 E. 208 St. Email:
Carson, CA 90810 Website:www.hksusa.com 24 miles

--------------------------------------------------------------------------------


G & R Manufacturing Telephone: 661-947-6388
313 East soledad Pass Road Email:
Palmdale, CA 93550 Website: Model 224xLC 25 miles

[Satisaii]

And it would not start this morning.

It had about 30 seconds of cranking then the battery acted dead. So I put it on the charger and did the following:

Discovered that the screw holding the ignition switch was loose.
Tried to crank it using a screwdriver, no start. I do have fuel pressure, suspect ignition is not working.
Pull computer. Looks good, put computer back. No start.
Unplug AEM, put in stock coils, and it starts.
Plug AEM back in. Pull stock coils. It starts.
So I put dielectric grease on all of my connections, and put a better ground on the engine. Took it for a drive around the block. No problems. I hate "fixing" a problem without knowing what it was.

The whole time I was working on it, the battery was on the charger. Is it possible that the AEM is less tolerant of a low voltage situation than the stock coils?

And since I am not an EE, another question. Since I hooked these coils up in series, am getting the full effect of the 52,000 volts? Or am I loosing some to the wasted spark?

[Tom @ Fast Forward]

I can't answer those questions now but should be able to as soon as the ones I bought get here.

My guess is that your problem and voltage sensitivity is due to the ignition signal from the ECU and/or Timing Card. We will know the answer to that as soon as we get them too.

[Digitac]

I'm sure we could send Bill over for a price.

Hey, I'd chip in for that! My car should be back together next weekend but then I need to put the break-in miles on it before it's off to the dyno for tuning. Maybe we could find a good shop, schedule a dyno day for all the so-cal guys and hire Bill for the day? Whatcha think?

[Tom @ Fast Forward]

Let me know. I'm sure we can work something out.

[Satisaii]

I would have liked to do that, but I am trying to get the car ready to go to Buttonwillow on the 27th.

On another note, how important are the break-in miles? I am having trouble finding the time to put that many miles on the car. I think that I may be up to about 70 miles since I did the rebuild last year.

[MX-Drew]

Tom do you remember my problem with a timing card?

When it was cold one coil (2 cylinders) would get no spark but once warmed up or the car had been sitting in sunlight it would run fine. To prove the point I started the car and it was only running on 2 cylinders (some how) stopped the car disconnected the timing card ran fine then put the card back and it mis-fired. Tom replaced the card and the car has run fine ever since. I understand Tom could not find a problem with the card but maybe the output level from the timing cards can alter slightly with temperature etc.

Maybe the AEM does not "like" the output from the timing card?

[Steve in VC]

And it would not start this morning.

It had about 30 seconds of cranking then the battery acted dead. So I put it on the charger and did the following:

Discovered that the screw holding the ignition switch was loose.
Tried to crank it using a screwdriver, no start. I do have fuel pressure, suspect ignition is not working.
Pull computer. Looks good, put computer back. No start.
Unplug AEM, put in stock coils, and it starts.
Plug AEM back in. Pull stock coils. It starts.
So I put dielectric grease on all of my connections, and put a better ground on the engine. Took it for a drive around the block. No problems. I hate "fixing" a problem without knowing what it was.

The whole time I was working on it, the battery was on the charger. Is it possible that the AEM is less tolerant of a low voltage situation than the stock coils?

And since I am not an EE, another question. Since I hooked these coils up in series, am getting the full effect of the 52,000 volts? Or am I loosing some to the wasted spark?I assume you are talking about hooking the primary side coils. If so, you will reduce the spark.

A spark coil is charged (magnetic field built up), and fires when the power is removed. The energy stored is the square of the current. The current is limited by one of three methods.

Charge time, the longer the drive pulse, the higher the current. Two coils in series will reduce the voltage by half, the spark energy by 4 times.

Limited by the resistance of the coil, two coils in series also reduces the spark energy by 4.

Current limited, this may give you more spark, but still not enough.

Why did you hook the coils in series?

[Satisaii]

These are CDI coils, 1 coil per cylinder, with 1 capacitor per 2 coils. Supposed to be 520 volts to the coils. I hooked them up in series becuase the "in sereis" illustration in the manual seemed to best match the Miata computer output.

Thanks for the reply. I barely passed the "EE for ME" class, and that was many years ago. I should be better at it, but my engineering job does not require any engineering. I am getting rusty and not liking it.

[Tom @ Fast Forward]

The company I ordered my set from sent my PayPal money back. "Out of stock". When Bill gets back from Laguna Seca (Miata 20th Anniversary get together) and then WA state (Race Grandpa), we'll look at it again. Should be sometime next week.

[Satisaii]

If you want to pay for the dyno time, I would find a way to get my car out there. My budget will not allow for both.

[lowboy72]

I missed Satisaii's original reply to the cranking problem. I had a similar issue but mine would turn over only after every 4th or 5th try. I would idle fine but run like crap above 3500 RPM. I also just discovered that my tranny is borked (my wife is calling the car cursed). I bought the six speed used (supposedly with only 10k miles) . After about 5k additional on it, it will not shift into first unless slamming the shifter to the left and then up. I open up the top by removing the shifter and sure enough the gear oil is thick and a graphite color with metal shavings in it. This is why I am always hesitant to buy used parts, lesson learned.

I will not be able to get my car into the shop until April for the tranny but I will try the AEM again with my new battery. The old one finally kicked after its fourth time running down to no charge in the extreme cold.

[Tom @ Fast Forward]

James,

If your car will be down awhile, send me the AEM and we'll work it out.

[Satisaii]

I would idle fine but run like crap above 3500 RPM.

Interesting. I have now done a few trips around the block, and I would say the car starts and runs like stock ( with the exception of that one morning, and I am not convinced the AEM was the problem.) But I have been taking it very easy and only have revved it up to 5K once. I did put the belt back on the SC. The intake I have is not suited to NA operation. Until I get a few more miles on it, I am driving with a very light foot.

[Tom @ Fast Forward]

Maybe when Bill gets back. Week after next?

[Satisaii]

I have a track day in Buttonwillow on the 27th. My plan is to take the Miata since doing track days is the only reason I own it. I need to get it done before then. I would rather do my testing on a dyno where we can see the health of the car, and not on I5 (or I10.) I can do it here, but then I miss out on your expertise with this car.

It is possible that I could drive out today or tomorrow (providing Vivian does not rip my head off when I tell her.)

[Steve in VC]

This is the way I am going to hook it up:

Brown to - Coil 1
Tan to + Coil 4
Jumper + Coil 1 to - Coil 4

Orange to - Coil 2
Pink to + Coil 3
Jumper + Coil 2 to -Coil 3

Set unit to wasted spark. And watch for things blowing up.

Does the Miata ECU provide a ground trigger or a positive trigger? I don't have the tools to figure this out.In looking at the AEM instructions. I would parallel the trigger wires for 1 & 4, and for 2 & 3, instead of connecting the coils in series. They show the series connection, but if you are sensitive to voltage, individual drives is better.

See the pictures, make sure I understood you connection looks like "as wired" (except the unused trigger wires are grounded), my suggestion is named "suggestion"

[Satisaii]

That looks like how I wired it.

The AEM is sensitive to input voltage. Will wiring it like you suggest affect the trigger voltage?

[Tom @ Fast Forward]

I just don't have the time this week. Especially with Bill heading out. Let me do a little investigating on the ignition circuit and Timing Card today and I'll see if I can come up with a simple solution.

[Satisaii]

I got in trouble yesterday. She is not going to let me go anyways. I will be in a better place financially next month, and we can make some arrangements then to test the AEM thing. I will just tune it for fueling this week.

The kit came with the exact right number of connectors and what-not, so making a change is not plug and play easy. I would like to have some reassurance that it will work before cutting and splicing wires.

[Satisaii]

I went ahead and started to wire it in and discovered a problem. Wiring it in the way Steve suggests will lead to each capacitor needing to discharge every 180 deg of rotation. I think this would lead to a high RPM miss if the caps don't recharge fast enough. I am going to "switch" coils 3 and 4 such that the "pink" cap triggered by the orange and gray wires goes to cylinders 2 and 3 instead of 2 and 4.

I am going to do this by hooking the violet (#4) trigger input wire to the 2/3 output wire on the computer, and hooking the yellow (#3) trigger input wire to the 1/4 output on the computer. I think this will fix that issue.

[Satisaii]

It starts, runs, drives, revves up to past 5K rpm. I can't really tell if it is any better, but it was a very short drive. I will take it out on a longer drive here in a bit.

[Satisaii]

I have now done about 20 miles with it. Been up to 70 mph, and there seems to be no real problems.

Having said that, the idle seems to be a little less consistent. I might just be reading something into it. It would need another observer to double check my hunch. It also seems to have an occasional miss just cruising down the freeway. Once again, it may just be me being overly sensitive. I have not driven this car down the freeway (so to speak) in the last 6 months. And it is nowhere near being stock

[Satisaii]

Tom,

This is the thread detailing the way I hooked up the AEM. There are some pictures attached to one of Steve's posts that come close to what I am describing here. It is not hooked up according to any of the AEM instructions, but according to Steve's suggestion with the change described below.

John

I went ahead and started to wire it in and discovered a problem. Wiring it in the way Steve suggests will lead to each capacitor needing to discharge every 180 deg of rotation. I think this would lead to a high RPM miss if the caps don't recharge fast enough. I am going to "switch" coils 3 and 4 such that the "pink" cap triggered by the orange and gray wires goes to cylinders 2 and 3 instead of 2 and 4.

I am going to do this by hooking the violet (#4) trigger input wire to the 2/3 output wire on the computer, and hooking the yellow (#3) trigger input wire to the 1/4 output on the computer. I think this will fix that issue.

[lowboy72]

I am going to try this as well. In all honesty I did not wire it up exactly as shown in the picture. I always had 1/4 and 2/3 together with the 540v rails. What I did different was follow the instructions closer by grounding yellow and violet. I then spliced white output (brown) to both (-) on 1 and 4 and green output (orange) to (-) on 2/3. I figured that since it is wasted spark that this should not be a problem. I am going to try Satisaii's wiring but I was hoping someone could help me understand why my wiring would not function properly.

[Tom @ Fast Forward]

James,

Here is before and after.

[lowboy72]

Are the coils numbered correctly in that diagram? It looks as though it fires 1-2-3-4 instead of 1-3-4-2.

[lowboy72]

So either my car is cursed or my twin fire unit is bad. I wired my car up exactly as described in the diagram and while I can start the idle is off and it will miss if I press the accelerator. I test all four coils and they are fine. I think that I am going to call AEM today to initiate a RMA.

[Tom @ Fast Forward]

Wait until I get there and confirm but yes, the diagram is correct as the change at the input side corrects the coil numbers.

[lowboy72]

Wait until I get there and confirm but yes, the diagram is correct as the change at the input side corrects the coil numbers.

Do the coil numbers indicate position or firing order? Also is switch 2 off or on?

[Tom @ Fast Forward]

We will take a look and confirm. John now thinks he put coil 3 on cylinder 4 and coil 4 on cylinder 3.

I wont be able to verify for an hour or two as I have never seen them but it makes sense that you would have to swap the two coils as well. Sorry about that.

[Tom @ Fast Forward]

Just found this one. Looks interesting. The approach is to increase the voltage at the coils as high as 20 VDC.

http://www.kennebell.net/accessories/boostaspark/boostaspark.htm

[Satisaii]

I think we finally got my car running pretty right a couple of weeks ago. We might have ruined yet another cat when my FPR dumped fuel at 100+ psi into a vacuum line (car ran SUPER rich for about 10 minutes of trouble shooting), so we are not totally certain of the "final" results at the dyno in Arizona. The engine ground MAY not have been good enough either. Both the cat and the ground have been replaced, and I will be dynoing the car again this weekend. Well, I had a test pipe made. No more cat.

Having said all of that...

We did do some back to back runs comparing stock to AEM coils. No difference at the 235 HP level. I still suspect the ground, and will report the numbers from this weekend later.

[FormerDatsun510Man]

Your setup was within 5hp of what my R4 made with the same pulley, so I think we got yours running right and I don't think the cat has been toasted. Removing the cat may get your setup matching what mine made nearly exactly.

Bill

[Satisaii]

The cat did not look as bad as the one lurking under the house. That one died the noble death to become a test pipe. I will hang on to the other for some unknown reason. I really need to pull all of the parts out from under the house and sell or trash them.

Remember how much trouble it had with slow starts? Thought it may be a bad battery? Gone with the new ground cable.

If it does good on Saturday, I will declare it healed. I have signed up for a day at Sears Point, so it better be running good.

[Tom @ Fast Forward]

Good luck. Glad you fixed the bad ground.