newton

iTrader: (4)

This morning, when I went to start the car, the motor revved much higher than normal, 2-3k rpms and then just stalled on me. I didn't release the clutch or anything, it just revved up high and all of a sudden the rpms dropped and it stalled.

I started it again, and everything seemed fine except the idle speed was high (1500-1600 rpms whereas normally a it would idle at 1000-1200 rpms on a cold start).

I drove it around, warmed it up, and the idle was fine again. Should I be worried?

ae13291

iTrader: (8)

if the problem comes up like this every morning then u should be worried! but if im not mistaken this might have something to do with your IAC solenoid on your throttle body! that is what controls the idle speed back to the factory 700rpm when it is warm, BTW is that a M6 B4C camaro???

newton

iTrader: (4)

I don't believe it's a B4C. My car never idles at 700 rpms.

ae13291

iTrader: (8)

then whats ur normal idle??? all M6's should be at 700rpm

FreByrd

iTrader: (1)

yep my car does the same thing on cold morning starts only. When the weather is warm my car is just fine but once winter came now it does exactly as you described.

1st start on a cold day it will idle up to about 2500 then come back down to 800rpm then just die, i have to restart it again. Several repeats of that and it will slowly hold idle but run rough, then eventually smooth out as the car warms up. Then for the rest of the day the car is just fine as can be. Its just that first cold start in the morning.

I've got autotap an been trying to figure out what it could be, but im learning what values to look for so i'm new to this as well.

Sorry i didnt have much to add. But if i figure it out i'll post back up again.

newton

iTrader: (4)

About exactly at 1000.

ChocoTaco369

Either your tach is off, you have an aftermarket tune or something is screwed up then.

We're not talking about the idle when it's cold out. When you first start the car, the car will idle higher. We're talking about the idle rpm's when the car is completely warmed up. Drive it around for 10 minutes, then stop and put it in neutral. In an M6, it should idle at ~700 rpms in neutral when fully warmed up.

The A4's are a tad higher. My A4 idles at about ~800 rpms in neutral and ~550 rpms in D.

newton

iTrader: (4)

I'll drive around for day and it will idle at 1000.

ae13291

iTrader: (8)

wow thats weird!! do u know if u hav a ported throttle body???

newton

iTrader: (4)

Aside from Flowmaster mufflers and Z06 wheels, I'm pretty sure this car is bone stock down to the paper filter. However, I can take it apart and take a look at the throttle body.

Another possibility is that my tach is off. Idling at 1000, it sounds very normal.

ChocoTaco369

Hmm...perhaps the idle screw is messed up on your throttle body. Try playing around with that. The high revving cold start may be a side effect of the idle screw being messed up, so if you fix the idle screw and your idle drops to where it should be (~700 rpms in neutral when fully warmed up), perhaps the issue will be gone. You just may need a slight TB adjustment.

newton

iTrader: (4)

I did a quick search for idle screw and found it's located next to the TB upside down...or something along the lines of that. Any pictures?

I will try adjust it. If 700 rpms is normal while warmed up, how high does a M6 car idle while cold?

krayzie7th

do you have the ses light on? could be your map sensor or iac valve try cleaning both.

newton

iTrader: (4)

No SES light. Is MAP the same thing as MAF?

chromeplated500

iTrader: (10)

monitor it. get it checked with a scan tool. that would freak me out if it just started revving.

ChocoTaco369

No. I think the MAP sensor is behind or around the intake manifold. I don't know where it is; I never really looked.

krayzie7th

oops i meant to put MAF.

canadian z28

Do not adjust the set screw. These cars are computer controlled. It won't do too much because the computer will over compensate. Why don't you start by cleaning the throttle body. Million bucks says it is black and gunky. Some TB cleaner and a tooth brush and scrub anywhere the TB blade touches. Then take the IAC motor out (don't loose the screws) and clean that and the bore it came out of with your pinky finger and a rag. That just might fix your problem.

newton

iTrader: (4)

Okay, so I cleaned my TB in and out and threw on an aftermarket lid while I was at it. The problem persists. It only happens when the car has been sitting for a while (such as overnight) and is really cold outside (under 40-45 degrees, which in this case, has been like this every night recently).

I've searched a few more threads and it seems like I need an retune for my idle? The car is basically stock. I have no idea if the previous owner had modified it's tune.

FreByrd

iTrader: (1)

I solved my cold start problem. Intake manifold was not torqued down enough. Torqued all intake manifold bolts down to 89lb in's and in sequence as it should be. 2 mornings now and i can go out in 0-10 degree weather and it will start up and idle just fine!!

Before, it would start, rev up to 2-3k rpm then slowly come back down and just die. Repeat that about 5-8 times and slowly it would hold idle, but run really rough and eventually smooth out as the car warmed up. Then for the rest of the day it would be fine, it was just the 1st cold morning start, summer time the car was just fine.

Replaced fuel filter, didnt help
New plugs, didnt help, i thought it did.
Seafoam, car idled smoother but no fix
cleaned MAF, no difference
Autotap readings were all normal, no SES light.
Car is stock BTW.

jason