Ky944TurboNewbie

I am hoping you can help me figure out why my car is stalling when the gas is let off. The idle is dropping too low. Sometimes it recovers and sometimes it doesn't.

I took a short video to show what is happening.

http://s1227.photobucket.com/albums/...t=d56f93ad.mp4

Thanks,

Michael

Ky944TurboNewbie

I have checked the AFM and TPS per Clarks Garage procedures and they check out ok. I cannot find a vacuum leak using carb cleaner and spraying around all of the connections I can find.

joster86turbo

does your oil pressure always sit that low? is this at a cold start or operating temperature?

Ky944TurboNewbie

At cold start the oil pressure is much higher. Close to 5. This is when the car has warmed up.

Black51

That oil pressure is low. How long has that been like that? Have you checked the oil level lately? Probably something else, but the simple things are always the first things to check.

Check the ISV. Do you have an aftermarket boost gauge? If so, what vacuum are you seeing upon rev down/idle?

Black51

If it were a small vacuum leak, it probably would only show itself when under boost. If it were a big vacuum leak, the car would barely idle and have 0 power ever.

Ky944TurboNewbie

Ok... Oil level is good. I jumpered the b and c terminals on the diagnostic plug and it immediately wanted to die. Once I backed out the idle screw to where it would run at about 900 rpm's, everything seems fine now.

What is a normal oil pressure when the car is idling? It increases when given a little gas. the car hasn't been driven in about 2 years and needs to have the oil changed.

I just got the water pump, front seals, power steering rack, timing and balance belts and all rollers done. Please don't tell me I have to tear it apart again.

Ky944TurboNewbie

I just looked at the video. Now that the idle is holding better, the oil pressure is slightly better. I will change the oil and monitor it. It seems to be within the range of what is recommended by Clarks Garage now.

Thanks!

eric951turbo

I had a similar problem in the past. We changed the TPS, coil, checked all vacuum lines etc...
Nothing helped. The next solution was to change the AFM.

But then we had that crazy idea of opening the AFM cover and blow air with a compressor inside of it.

It fixed the problem 100%

choinga

I had a similar problem - cleaned up my AFM and it was much better (but soon after upgraded to a Vitesse MAF, so...).

I'd go through this process - pretty easy - biggest PITA is getting the cover off. I knew I didn't have any big vacuum leaks and my TPS checked out - but I went ahead and replaced it, my ISV and cleaned my AFM and my car ran great.

Ky944TurboNewbie

My AFM has been adjusted. Now my problem is back. Ran great this morning for a run around the block. After I clean it up and try to take it around the block again, it is back to running awful and nearly dying every time I take my foot off the gas. I thought maybe it was the the idle screw backing out or something. I went to jumper the diagnostic ports again and now regardless of how the idle is adjusted, it dies when the port is jumpered. Back to the drawing board.

Porsche Ober

sounds like the idle positioning switch. Have that problem in my car too. I just bumped up the idle rpms to about 1000 until i can replace it. it's buried in there....

toddk911

Bad AFM is perfect reason to upgrade to MAF.

But probably more the ISV.

Ky944TurboNewbie

I don't believe it is the ISV because the idle doesn't hunt. It works much better when the ISV isn't bypassed. Also, the car is really rough under load. I am suspecting a large vacuum leak. I just haven't been able to find it. I am gonna take it to the pros and let them figure it out. I will post the reason when it is found.

Ky944TurboNewbie

First report from the shop is that fuel pressure is about 3 times higher than it should be. I have ordered a fuel pressure regulator. Do you think this could cause the low idle and hard shudder?