Idle Droop Issues

[chuckerants]

Car: 99 hotside with PC Pro, 5th injector, Timing card, 115mm/65mm pulleys, SS controller for 5th injector, 180F T-stat, parallel fan mod.

Symptoms: Uh, idle droop.

Weather: Cold to freezing my bum off (for a SoCal native, or 35F~50F).

Lately, I've been experiencing bad idle droop. This is so strange as when I had no idle droop in the summer time.

Then yesterday as I was driving home, I noticed that I had no idle droop again.

Here's my theory:

Due to the hot summer temps, I installed a 180F and it worked great. Now that the weather has turned a bit chilly, I have noticed that the car takes forever to get to operating temps - around 200F.

I'm guessing that because the car is still in warm-up mode (around 180F is what the coolant temps seems to be), the ECU is still running pig rich. Which btw is another thing I've noticed. (My laptop is unable to connect to my WB so I can only go by the excess fuel smell).

So, because the ECU is adding more fuel thinking the car is still warming up, that is what's causing the idle droop while the weather is cold.

Now yesterday, as I was driving home, the coolant temp was at 200F~210F or normal operating temps and voile, no idle droop. *The ambient temps were around 10F warmer than the previous day.

So, what say you? Does my theory sound, well, sound?

I may have to get a 195F t-stat this weekend and do a swap and test my theory.

[socal pat]

My car goes out of warm-up mode well before 180*. When mine is cold it idles higher not lower until we get to like 120*IIRC on my scangauge.

[chuckerants]

I'll have to check the Factory Service Manual, but I've just been informed it is 165F where the car is out of warm up mode.

If this is true, then WTH is making the car run so rich until I get teh car nice and hot???

My car goes out of warm-up mode well before 180*. When mine is cold it idles higher not lower until we get to like 120*IIRC on my scangauge.

[socal pat]

Not to cornfuse things here Chuck, but we also need to go back to the idle thing. Just running a rich warmup condition should have you idling high unless it's so rich you are choking it out. In that case the #1 O2 sensor would be suspect, no? Either that or the ECU is not seeing the right amount of airflow. AFM?

[Gman7007]

I beleive it has more to do with warming up the TB. I have the factory TB without the coolant hoses running through it. Even in cold weather once the entire engine bay is warm all is fine.

[dazooom]

Chuck...On my 2001 H/S with a 180* thermostat, I'll get idle droop, no matter the outside temp, (25*-95*), until my coolant temp gets to 160*. I NEVER get any droop after it gets to that temp. I just normally start the engine, and let it idle till it gets to 160*, which takes anywhere from 6-8 minutes, depending on the outside tempature. If I'm in a hurry, and can't wait that long, I just keep an eye on the tach, and give it gas, when it starts to droop.

[socal pat]

I've been mulling this over. How was your idle last winter? If this is a new thing then I wouldn't just chalk it up to Miata behavior because some other people have it. When did you last check your coilpacks? My car started acting a bit funny. A tiny bump in the idle, and idle swing when first started. I kept meaning to get around to adjusting my idle up a bit since I had R&R'd my motor and SC, but once warm it was fine so I kept putting it off. A few weeks ago I got a misfire #3 code and replaced the coilpack. Night and day. No more cold start idle swing, no more anything. IOW if this is new then there is a cause and a cure.

[99mx5]

Idle droop? Whats that? ;)

[chuckerants]

I really don't remember if I had the idle droop last winter. Though I do remember having random idle droop when I first got the car - before the SC.

As I said, the Miata is now my DD so I noticed a lot more than I used to. Or should I say every little thing annoys me. lol

I bought a new CP soon after my original SC install thinking my problem at the time was CP related (when in fact it was an installation problem) so I have a new CP. I have to check whether I have the old CP or the new one on my car at the moment.

But wouldn't I get a CEL if it was the CP?

I've been mulling this over. How was your idle last winter? If this is a new thing then I wouldn't just chalk it up to Miata behavior because some other people have it. When did you last check your coilpacks? My car started acting a bit funny. A tiny bump in the idle, and idle swing when first started. I kept meaning to get around to adjusting my idle up a bit since I had R&R'd my motor and SC, but once warm it was fine so I kept putting it off. A few weeks ago I got a misfire #3 code and replaced the coilpack. Night and day. No more cold start idle swing, no more anything. IOW if this is new then there is a cause and a cure.

[chuckerants]

I also carpool with someone and he weighs pretty close to 300 lbs so I don't think that's helping my powerlust any or my worn suspension. :(

Though I get a wee bit of amusement at his expense watching him folding himself into my pax seat. Lucky for him, he gets to drive next week. :)

[socal pat]

I really don't remember if I had the idle droop last winter. Though I do remember having random idle droop when I first got the car - before the SC.

As I said, the Miata is now my DD so I noticed a lot more than I used to. Or should I say every little thing annoys me. lol

I bought a new CP soon after my original SC install thinking my problem at the time was CP related (when in fact it was an installation problem) so I have a new CP. I have to check whether I have the old CP or the new one on my car at the moment.

But wouldn't I get a CEL if it was the CP?
As I said (and did) I finally got around to changing my coilpack after getting a CEL, but looking at the nasty burned-up used thing that I took out, I should have changed it months prior to getting the CEL. Anyway I was using the coilpack as an example of how idledroop is a symptom and not a "feature" of a '99-'00 Miata.

[Tom @ Fast Forward]

Chuck,

That post brings back memories of the first time I met you. You drove over from CA to drive my car. We had lunch (Rockbottom Brewery, I believe) and then you took it for a test drive. As we were 1/4 mile from I-10, I figured that you would pull out and turn right and head for the interstate. Instead, you turned left and drove into a subdivision. I was throughly confused as you never got over about 25 MPH and fiddled with the AC, blipped the throttle randomly, braked hard and miscellaneous other things. Then drove back to Rock Bottom Brewery so I could pick up my wife. If I recall, you said you didn't care how it drove, only cared about idle and were totally amazed that it idled flawlessly under all of the tests. Then you went back to CA. You are welcome to refresh my memory about that visit.

I figured I'd never see you again. I guess you liked my company so much, you had to move to Phoenix to be close. Ever since, you had pretty decent idle, for a non-Coldside install. Not to mention going from 170WHP with knock to 210WHP with no knock. :)

[chuckerants]

Yup, and I'm still blaming my power addiction on you. lolChuck,

That post brings back memories of the first time I met you. You drove over from CA to drive my car. We had lunch (Rockbottom Brewery, I believe) and then you took it for a test drive. As we were 1/4 mile from I-10, I figured that you would pull out and turn right and head for the interstate. Instead, you turned left and drove into a subdivision. I was throughly confused as you never got over about 25 MPH and fiddled with the AC, blipped the throttle randomly, braked hard and miscellaneous other things. Then drove back to Rock Bottom Brewery so I could pick up my wife. If I recall, you said you didn't care how it drove, only cared about idle and were totally amazed that it idled flawlessly under all of the tests. Then you went back to CA. You are welcome to refresh my memory about that visit.

I figured I'd never see you again. I guess you liked my company so much, you had to move to Phoenix to be close. Ever since, you had pretty decent idle, for a non-Coldside install. Not to mention going from 170WHP with knock to 210WHP with no knock. :)

[chuckerants]

Time, AFR, RPM, TPS

12:24:47 PM, 10.90, 6472, 97
12:24:47 PM, 10.90, 6436, 97
12:24:47 PM, 11.00, 6436, 97
12:24:47 PM, 11.00, 6436, 97
12:24:47 PM, 11.00, 6436, 97
12:24:47 PM, 11.00, 6436, 98
12:24:47 PM, 11.00, 6472, 97
12:24:47 PM, 11.00, 6472, 97
12:24:47 PM, 11.00, 6472, 97
12:24:47 PM, 11.00, 6472, 97
12:24:47 PM, 11.10, 6400, 97
12:24:47 PM, 11.10, 6472, 97
12:24:47 PM, 11.10, 6508, 97
12:24:47 PM, 11.10, 6508, 97
12:24:47 PM, 11.10, 6508, 97
12:24:47 PM, 11.10, 6508, 97
12:24:47 PM, 11.10, 6583, 97
12:24:47 PM, 11.10, 6545, 97
12:24:47 PM, 11.10, 6698, 97
12:24:47 PM, 11.10, 6436, 97
12:24:47 PM, 11.10, 6545, 97
12:24:47 PM, 11.10, 6545, 97
12:24:47 PM, 11.10, 6545, 97
12:24:47 PM, 11.10, 6545, 97
12:24:47 PM, 11.10, 6659, 97
12:24:47 PM, 11.20, 6583, 97
12:24:47 PM, 11.20, 6621, 97
12:24:47 PM, 11.20, 6583, 97
12:24:47 PM, 11.20, 6621, 97
12:24:47 PM, 11.20, 6508, 97
12:24:47 PM, 11.20, 6621, 97
12:24:47 PM, 11.20, 6621, 97
12:24:47 PM, 11.20, 6659, 97
12:24:47 PM, 11.20, 6659, 97
12:24:47 PM, 11.20, 6659, 97
12:24:47 PM, 11.20, 6659, 97
12:24:47 PM, 11.20, 6659, 97
12:24:47 PM, 11.20, 6698, 97
12:24:47 PM, 11.20, 6659, 97
12:24:47 PM, 11.20, 6737, 97
12:24:47 PM, 11.20, 6698, 93 <------------ Where I lifted
12:24:47 PM, 11.20, 6659, 86
12:24:47 PM, 11.20, 6737, 76
12:24:47 PM, 11.20, 6737, 57
12:24:47 PM, 11.20, 6698, 34
12:24:47 PM, 11.30, 6698, 15
12:24:47 PM, 11.30, 6659, 5 <------------ No throttle input
12:24:47 PM, 11.20, 6508, 4
12:24:47 PM, 11.10, 6436, 3
12:24:47 PM, 11.10, 6365, 3
12:24:47 PM, 11.10, 6295, 2
12:24:48 PM, 11.40, 6227, 2
12:24:48 PM, 11.80, 6436, 2
12:24:48 PM, 12.40, 6472, 2
12:24:48 PM, 12.60, 6545, 2
12:24:48 PM, 12.80, 6583, 2
12:24:48 PM, 13.00, 6621, 2
12:24:48 PM, 13.10, 6621, 2

[chuckerants]

Take a look at where I lifted and where the TPS shows pretty much 0% TPS. Shouldn't the AFR read high like 21:1 or leaner? If not right away, how long does it take?

What doesn't show on this log is that the car stalled after I lifted.

I tried this when I was driving very slow, say 30 MPH, then hit the brakes with 50% input and the AFR read as rich as 11:1. This is what it reads as the car develops idle droop.

Any ideas as to what I can do to cure this? Why is it so rich when I lift?

[Tom @ Fast Forward]

Looks like all of those readings are within one second. Might take a little more than one second for the A/F to react?

I read 12:24:47 as 24 minutes and 47 seconds after noon, right? That data logger logs a lot of data in one second. Show us up to 12:24:50. About 3 seconds worth.

[chuckerants]

Tom,

The AFR readings are pretty much the same until after I stop. THEN, the AFR stabilizes at around 14~15:1. By that time, the droop is over or the car has stalled.

[chuckerants]

Also, the AFR does not seem rich at all during my normal commuting type driving yet it smells very to me. Hmm.

[Tom @ Fast Forward]

That smell could be a clue too. I wonder if you have a vacuum leak somewhere? Anytime you lift in gear letting the engine do braking, the A/F should almost instantly go lean.

BTW, I just got a nice letter from the Utah Bureau of Criminal Investigations. :) Did you get one too? ;)

[chuckerants]

If I had a vac leak, I'd know it by my gauge, but it seems to be spot on.

I wonder if the SS is adding fuel when the ECU/PC Pro isn't when I lift? I guess I can test that by unplugging the 5th injector and take it for a slow drive and lift to see if still does it.

As for Utah, I had a brain fart and forgot that I'm a NATURALIZED citizen and did not include a copy of my US Passport. I also did the same thing for Joanne and AZ. So, yes I did get a letter from Utah, but now I get to wait some more. :(That smell could be a clue too. I wonder if you have a vacuum leak somewhere? Anytime you lift in gear letting the engine do braking, the A/F should almost instantly go lean.

BTW, I just got a nice letter from the Utah Bureau of Criminal Investigations. :) Did you get one too? ;)

[Tom @ Fast Forward]

Is your A/F 14.7 under cruise?

Ah, you're one of those 'legal' immigrants. We don't get many of those. ;)

[chuckerants]

I'm pretty sure at cruise the AFR stays around 14~15:1. I'll check the log again to be sure.

As for me, yes, we actually did it the legal way with real papers and all. :)Is your A/F 14.7 under cruise?

Ah, you're one of those 'legal' immigrants. We don't get many of those. ;)

[Tom @ Fast Forward]

To confirm, if you downshift and lift you do not get a lean condition?

We'll have to talk sometime about legal immigration citizenship. Our daughter-in-law will be almost 10 years before she can get it. when she first came over and married Hans, the government told her that if she went back home to visit her family, she would not be allowed back. Those were two hard years for a young girl, newly married, away from home and family and country. The 'legal' way is the hard way. Then the government gave her 90 days to get married or go home and the church said minimum of 6 months of marriage counseling before they would marry them. So they got married by a judge and, six months later, married in church. Now, after 5 years, in May they are going to deliver grandchild #11. :) That'll break the tie. Right now 5 boys and 5 girls. Their first child will be a boy. :)

[Satisaii]

Drifting off course here?

Vivian had a company sponsorship that gave her a green card. She became a citizen last year, which was about 8 years after she came over, but about one year later than she could have. She drug her feet somewhat.

Now that things are getting tight, she is saying that she can just go back to China and work. I have to point out that is not as easy as it was when she was a Chinese citizen.

[Tom @ Fast Forward]

I do tend to do that, don't I? :)

Could she stand the increase in pay if she went back to work in China??? :)

[Satisaii]

Those are some plans of last resort. It will have to be MUCH worse than it is now for us to move to Shanghai.

The thing is that she has a place to live there that is paid for. We can live there sooo much cheaper than here.

[Tom @ Fast Forward]

As of early yesterday morning, Hans is in mainland China. I think he is starting to like it over there. :)

http://www.FastForwardSuperchargers.com/Tesla.wmv

[Satisaii]

2 hour run time? Pretty cool.

I like to visit, but I would not be able to drive there or ride my bike. Add in some poor air quality and I don't think I would want to live there for long.

[MX-Drew]

That's done it, when I'm over in June I'm staying there.

How are the university buildings coming on Tom? May be there is a job or two there.

I will have my MX-5 (Miata) shipped out so you will have a RHD car to test on Tom.

Sorry off topic.

[Tom @ Fast Forward]

The Central Arizona University branch is now open and you can walk there from here 3-4 blocks away.

Maybe we will need to test the new sparkplugs on Chuck's car when I am done testing on mine?

Drew, I still think your car is one of those with not the best spark. The new plugs should be here by Wednesday. I will try and test them on Thursday. I would love to find my missing 30 WHP.

[Tom @ Fast Forward]

Never been there myself. We do have a kit in Hong Kong. Not quite the same though.

2 hour run time? Pretty cool.

I like to visit, but I would not be able to drive there or ride my bike. Add in some poor air quality and I don't think I would want to live there for long.

[speedfreakrx7]

What happened with the idle droop, rich at drop throttle?