Tip in hesitation & idle issues

[Godless Commie]

Hi all,

I just finished installing a BRP MP62 hotside with a BBK throttle body, TDR intercooler and a trio of PcPro, E-Cool and Timing cards. (sounds sooo simple when you fit them all in one sentence, doesn't it?)

I did set the idle. It ran perfectly at 900 rpm. Turned off, re-fired a bunch of times, all was OK.
But, once the car sits for a bit and cools down, it will not hold idle anymore. Keeps dying.
Idles after about 20 minutes of driving, and dies intermittently even then.
No cold fast idle, at all..

Any thoughts? Should I "mess" with the TPS? (Tom, FYI, I never took Jim's TPS off the TB. Figured it would be adjusted already. So, I am currently running with that.)

Second issue is, tip in hesitation.. between 1500 to 2000 rpm. I mean there are times when the rpms HAVE TO come down to those levels in city driving..
What happens is a major bog, followed by a major surge. Visions of the rear bumper of the car in front of me on my lap. I clutch in and modulate the gas as best as I can.
Again, do you think this would be TPS related, as well?

On a second thought, I do remember fiddling with the timing card a bit while I was very frustrated trying to get the car running the first time around. Could I possibly have knocked it off kilter?
How would I verify it is at the default settings?
Would the timing card pull that much timing at around 1500 to 2000 rpm?

Any ideas?

[Tom @ Fast Forward]

1) COLD IDLE - A cold vacuum leak comes to mind. Something that warms up and then goes away. Check all of your hoses. No TPS adjustments on the 99-05.

Could be related to above. Do you have a vacuum gauge? If so, what do you get at idle?

Timing card should be Green - 0, Yellow - 1.5 and Red - 2.5. The fuel cards don't work below 1500 RPM as you should not be trying for boost that low. That is where you can bend rods with boost at 1500. Is this happening in 1st gear? Timing card doesn't pull timing until 2200 RPM.

[Godless Commie]

Tom, its 3 am here in Istanbul :)
I'll check things over tomorrow. I do not have a vacuum gauge, but I guess I'll have to find one.
Fairly sure there are no vacuum leaks. I did not remove any hard parts that would affect vacuum. And, I made very very sure all vacuum hoses were nice and tight, with clamps on them.

I am not using a restrictor in the 3/8 vacuum line coming from the crankcase. You had said you did not use one in Jim's case. Could it be that I may need it?

And, if I had a vacuum leak, wouldn't I get a high/irregular loping idle? I mean, the car dies as soon as I fire it up. I have to heel and toe out of the driveway!

[Tom @ Fast Forward]

Hmm. That didn't seem to stop you from trying to call me at 5:45 the other morning. :)

The restrictor is more of a cure for hot idle problems. We'll know more when you get the vacuum numbers.

[Godless Commie]

Was it really 05:45? Soo sorry.. I though I had figured out the time difference..

It was late afternoon here, and I was pulling my hair Tom.. I thought you would understand.

Anyway..

I went out to the driveway this morning to the check the car for vacuum leaks, found nothing..

Then, I started it.

As soon as it revved for a bit A HORRIBLE RACKET STARTED!! Knocking and trying to tear itself apart. I was mortified. Dove into the driver's side through the window and shut the engine off as soon as I possibly could.
The engine stopped, the noise kept going and going and going..
You can imagine all the different colors my face must have gone through before it settled into a nice beet red.
Turns out, just as soon as I fired up the engine someone a couple houses down had started a huge hydraulic pile driver.. The beat per minute matched the revolutions per minute of my engine!
I must have eaten my cigarette in those ten seconds!

Here's what I have found so far:
I guess I was a bit impatient with the idle adjustment, and went a bit too aggressive with the throttle stop. Much smaller increments while adjusting the idle made an appreciable difference. I tried a few different rpm levels, and finally settled at 1000 rpm for now. I guess that will be a nice base for the car to "learn" everything from there. I have to slightly blip the throttle when I first fire up the car in order to help the idle to settle, but I suspect that will go away in a couple days.
I even considered to pull both the BTB and the IAC to disassemble and clean them thoroughly. (I do know GM IAC pintles were notorious for coking, and cleaning them used to do wonders..)

I also made my own restrictor by stuffing steel wool in the crankcase vent hose, and it helped a bit, as well.

Drove the car for about a mile, no hesitation...so far.

[Tom @ Fast Forward]

No problem. I turn the ringer off at night these days. I just saw the missed call and the time. I understand completely.

I have had a similar situation on at least one occasion. :) They are heart stoppers. Eating those cigarettes is no better for your health than smoking them. ;) Especially if they are lit.

The throttle stop should be adjusted no more than 1/8 to 1/4 turn. Then you need to wait a day or so before making any other adjustments to give the ECU time to adjust. The BRP hotside is even a bit more sensitive than the Coldside because of the throttled volume. Especially with the A/A IC.

Not much to clean in the BTB or, hopefully, in the IAC. I wouldn't rush to do that.

I will send you a proper restrictor. I'll support the kit as best I can even though it has the wrong three letters on it. ;)

[Godless Commie]

I went ahead and replaced the TPS.

The blower had arrived with the BTB and a TPS already installed on it.
It had been manhandled during shipping (halfway around the planet) to the point where the outboard mounting bracket was bent. The brass elbow vacuum nipple for the bypass valve on top of the blower was also bent.
I thought with that much jarring and physical damage to solid chunks of metal (despite Jim's incredible padding and boxing job), the TPS might have suffered some invisible damage, as well.

So, I replaced it with the one off my original throttle body.

Guess what.. The car does run smoother now.

I also removed the IAC valve while I was at it and inspected it.
I activated the valve watching for pintle movement and noticed that the pintle seems to be moving too little in there.
Is there a spec for the IAC valve?
There is an allen setscrew on the far end of the IAC, which is connected to the pintle assembly. Does that mean adjustments can be made on it?

Oh, I still haven't managed to find a vacuum gauge, Tom. I do know it's paramount to know the amount of vacuum before any solid conclusion can be reached. I may be able to get my hands on one tomorrow.

On another note, I decided to approach the idle issue from the other side of the problem.
When I had set the idle at 950 rpm, the car kept dying at stops. It would also not want to stay running when started cold.
What I did is, I intentionally set it a bit high.
I figured it could do its learning thing "down" from there, and I could keep driving and not worry about whether the engine would die coming up to a red light.

So, this is where I am at with this at this moment.

I'll post the vacuum numbers as soon as I can.

[bogey]

In my experience with a BRP hotside on my 97, setting a high idle was rather normal. The BRP hotsides are notorious for idle droop. Thats why I love the FFS Coldside so much better!

I know there are a lot of supposed cures for idle droop, but they are not universally effective. You may have to set it high and live with it.

[Gman7007]

...setting a high idle was rather normal. The BRP hotsides are notorious for idle droop.....

Ditto....I can relate!

[Godless Commie]

Problem solved..

Rock steady idle, nice cold starts, full IAC authority over idle level, great compensation for varying loads, correct recovery following decel runs..

Tip in hesitation is also "tip in let's go in a hurry" now.

For the record, I squarely place all the blame for my idle and hesitation problems on Tom for not calling me every hour, on the hour to remind me about the correct orientation of the MAF.
I just made sure, I mean so sure that the MAF was correctly installed in the car, I just referred to the original install position, completely disregarding the new air flow direction, which is actually backwards compared to the stock flow direction.
I just had a flash, followed by an irrestible urge to ask the first stranger I come upon in the street to kick me in the face, about the MAF orientation.
The rest is a minor idle adjustment, one hellacious test drive, mixed feelings of pure joy and incurable stupidity.
DIY installers, please do not install the MAF backwards.

Tom, you are an incredibly patient man. Thank you.

[Tom @ Fast Forward]

Well, glad it is solved. Sorry I didn't think of that. I have caught that on several Coldside installs.

[Godless Commie]

Tom, I was only kidding about the blame thing.. :yes:

[socal pat]

Yup, pretty much any "problems" you'll have with one of these kits is due to some bonehead move on the installer's part. Often it involves taking liberties like substituting duct tape for a propper vacuum fitting :redface: . Have fun!

[Tom @ Fast Forward]

I know you were kidding. :)

I am just a little disappointed in
myself that it never dawned on me to ask that question. That is a relatively common error. I know you don't blame me but I do. Now I will have to admit that I am no longer omniscient. :(

[Tom @ Fast Forward]

I think if you ran a poll, you would find MAF installed backwards is the top or very close to the top mistake.

[Godless Commie]

Actually, the MAF is just a resistor suspended in the incoming airflow that deviates in resistance with the cooling effect of the rushing air.
Theoretically, its orientation should not make a difference. But, in reality there are venturi and flow direction issues that come into play if installed backwards. That's why the engine did run for about a week. Ran poorly, that's another story.
It runs like the whole car is being shot out of a cannon now.

The reeeally embarrassing part of this mistake is, I am actually ASE certified. Got five of them. And enough advanced diagnostics certificates to cover the windshield. :redface:

[Godless Commie]

Oh, another thing..

I also trimmed the 3/8" vacuum hoses as much as possible, thinking shorter lengths would create a less "vacuum storage" volume, and maybe eliminate some of the IAC lag.
I am pretty sure it helped.