Hi,

I've got a 93 C2 cab with about 50k on it and a problem neither me nor my mechanic has been able to diagnose successfully. Since fall (here in Boston) car has been idling irregularly and stalling. Times when problems come are random. Most of the time when it's dry outside can be after a long drive or right after startup. A couple times it's happened after rain or after going through car wash.

Problem has been more consistent lately, possibly because it's been so cold outside the last few days. Here's a little more detail on what's happening:

Irregular Idle:
-Sometimes idle is steady and normal
-Sometimes it bounces a between about 400 and 600 rpm - takes about one second to bounce up and back down
-Sometimes it bounces a lot - between about 100 and 1100 RPM - takes about two seconds to go from 100 to 1100 back to 100. If I press the gas when it's in this mode and bring RPMs up over 2000, RPMs drop to zero immediately after I take my foot off the gas and the car stalls.

Stalling:
-Sometimes it just dies with no irregular idle preceding stall.
-Sometimes it goes into the 100-1100 unsteady idle mode then stalls

Restarting after Stall:
-Sometimes returns to irregular idle/stalling
-Sometimes returns to regular idle and runs fine
-No pattern I can figure out

Check Engine Light:
-Often on when car star

 

Hi,
It's worth searching the archives - this has been covered a lot before. I had hunting / stalling problems when I bought my 964 and new distributor caps / rotor arms fixed it.

Dave
90 C4

 

Dave is right, there are a lot of possible reasons, but they're all there in the archives.

My favourite - because it happened to my car and only came to light when everything else had been tried (& I suspected it all along, but that's another story) is the air-metering flap. Its contacts get tired and dirty - the engine-management gets the wrong idea about how much air is entering the engine. Sometimes it works, sometimes it doesn't. It's quick and easy to swap one from another car to check it.

 

On my 91C4, it was the idle control valve. It defied all methods of diagnosis, tho most stalls did trigger a check engine light which also provided no clues at the dealership. I think my cost was in the $200 range. AS

 

Fast enough ?
It's from a stock 965, not mine BTW

<img src="http://home.planet.nl/~jooscomp/299.jpg" alt=" - " />

 

Hmmmm...wrong thread..sorry !

 

hi,

I've also been through this before and have finally just about got it sorted. I think in my case it was a combination of numerous things that started to fail intermittently.

Nothing showed up as faulting on the Hammer, but it would just fail to run correctly. I changed the O2 sensor and DME relay first. This helped but then the problem returned. I then I changed all of the electrical components (changed coils, caps rotors, ignition leads, microswitches) which improved things further, but still the problem returned. Then I changed engine earth leads, vacuum hoses, oil cap seals and battery and still no joy. Finally after 18 months JZM found a fault with the earth to the battery and a fault in the Air Flow Sensor. Both were replaced and hey presto, now runs perfectly (for the moment at least).

And yes all this has been covered in archives before - but if we stop answering these questions directly, we don't learn new things that people have to add, I'm not a big fan of just shoving people off to archive (this isn't a flame, its just my opinion)

Hope this helps, If you want anymore info please just ask.

Ade.

 

Mr. Mahoney

The gist is that your mechanic will need to do a thorough investigation on your car and if we can come up with anything to check that he hasn't then all well and good. My hunting idel which started to happen recently was down to my lambda sensor becoming very slow so the DME couldn't control the revs very successfuly...

 

A quick thing to try...
pull your DME relay and tap it on the garage floor a few times. Then replace it and see if it is better. I know this sounds simple, but it takes 30 seconds and if it is it, then you spend $15 for a new relay and have saved tons of diagnosis time! Worth a try!!!

 

Actually - just buy a new relay and try that. Even if your old one is fine and not causing the problem, it's worth having a spare in the car. They do fail - and usually when they do you won't be going anywhere.

Dave
90 C4