Mr. C4

Volks,

6000 km. ago my workshop replaced the idle microswitch due to constant stalling (cold & hot)and the problem was fixed. Now the engine rpm. drops/dips very low and stalls as i clutch from 2nd coming to a stop or while parking etc etc. It's a little bit better if i switch off the aircon. The idle settles just fine if it's gradually "eased" down to 1000 rpm. Any ideas what might be causing this? I resetted the DME and then drove the car for approx. 25 min. as if i had stolen it!

Any ideas re. this is appreciated!

Ciao,

Johannes E.

porsche964

I'm sure there are unfortunately several items you can check, however I had a problem similar to this recently.

I replaced the DME relay; that did not help. I removed and checked my distributor caps to see if I might have a crack; none.

Then, I read a post somewhere about the proximity of the grounding cable at the left-side hinge of the engine hood, and its proximity to the ignition wires which connect the distributors to the coils. On my car, in fact, the ground wire rests against on of those ignition wires when the hood is closed.

So, I wrapped some electrical tape around the ignition wire to provide additional insulation, and I moved the grounding wire away by sliding it to the opposite side of the hinge.

Since I did this, I have not had a problem with the idle. Whether or not its dumb luck or a conincidence, we'll see. It's something you might consider trying.

Hope this helps.

Bill Wagner

Mr. C4:

I just updated my web site (click on the link in my signature) with a list of problem sources by possible causes.

The information is based on tables right out of the service manual for the most part, so it BETTER be correct. The two lists just correlate a problem with possible component failures and lists what components can cause which problems.

These are only lists at this time, but they at least point at possible causes.

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Jeff Curtis

Johannes, the issues that you're experiencing is VERY indicative of having a lightweight flywheel...but I can't remember if you have one or not?

My car stalls occasionally, usually when cold or if there's been an abrupt change in the weather, usually involving lower temperatures and high humidity. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

BUT, this all started when I installed a Lightweight Cup Clutch/Flywheel...so I expect it.

So, you've changed the idle stabilizer...it seemed to fix the problem and now it's back - you've got me there!

Maybe the dealer or whoever sold you the idle stabilizer will exchange one in the chance that it's defective?

There are a few places here in the States that offer an adjustable idle stabilizer...it's just a modified original that lets you have access to an otherwise unaccessible adjustment screw...to the tune of $300USD or so.

I'm considering having mine modified AND having a custom chip burned to alleviate the trouble...but am in no hurry.

Adrian

First thing to do is remove airbox cover, remove airfilter and check for oil contamination of the airflow sensor. Next thing to do is to check the airflow sensor connector for damage to the wiring and to check to see if the connector mod has been carried out.
Ciao,
Adrian
911C4

Ade - C4 91

Hi,

Yep, I'd agree with Adrian, have you topped your oil up recently? Overfilling will cause this problem.

Then I'd have another quick look at the idle switch, the vaccume hoses (Should hold their pressure and hiss when disconnected fcrom the tee join), the coils, ignition leads, caps ect, then the throttle body itself, which has a sensor that can be carefully cleaned.

As mentioned above, the grounding is very important, but so is good battery condition.

My expericence with doing a DME reset myself is that it doesn't seem to quite work as well as when JZMachtech does it. Not sure why, perhaps they tune some other parameters (mixture?) which subsequently get "Lost".

Anyway Good luck.

Ade