Ale_72

Ciao,
quick help (and suggestion on how/what to verify).
One month ago I sold mine 964 C4 in PERFECT conditions.
No issue ever. Starting fine, running smoothly, keeping the idle and really no problem at all.
Now, after one month, the new owner was contacting me to have some help since the car seems not to "keep the idle" (I know that it's a crap translation).
It means that the car, once started, if you do not keep pressed a little bit the gas, turns off.
On Monday I'll go to see the car. Is there any check I could do or any suggestion on how to fix that?
I probably was not clear. Fell free to ask and I'll try to integrate the info as much as I can.
Many thanks in advance.

Rocket Rob

Any changes or work done to the car since you sold it?

Ale_72

Zero. And less than 400km done.

Rocket Rob

Check the basics
- Battery voltage with car off & on
- V-belts - tight enough?
- Check engine light on?
- Do you have a scan tool - any error codes?
- Is the distributor belt broken? Do both distributor rotors turn together?
- When its idling, are all 6 cylinders firing evenly?

Ale_72

Ciao, thanks again,
- Battery voltage with car off & on - Need to check
- V-belts - tight enough? - for sure yes
- Check engine light on? - No
- Do you have a scan tool - any error codes? -I do not have it.
- Is the distributor belt broken? Do both distributor rotors turn together? - No issues here, it seems
- When its idling, are all 6 cylinders firing evenly? - Need to check

james_marshall

Id check that the idle microswitch makes contact - you can hear it click if you gently press it.
I had a very similar event with mine - but then I had been playing around with the throttle cable under the car and must have pulled it back slightly so it didn't 'seat' properly.

Might be be worth checking...

Ale_72

Interesting find.
For sure it has been already discussed. Do you know where I can find some pics to understand where and how to check?

james_marshall

The idle switch itself is the little red button in the middle(ish)of the screen

Ale_72

This will be for sure one of the first checks I'll do on Monday. Thanks again!

Peteinjp

I have been going through a very similar issue myself. One thing to check for sure is the DME relay. Other possible culprits are the ignition switch as well as the coils and distributor caps/rotors. I changed the coils and saw evidence that they were leaking. After changing the coils and distributor components a 200 km return to home was faultless. Though the distributor components were worn I think they were still probably working well enough. I think the coils were definitely part of my issue. Even after changing the coils I still had a no start problem and making a jumper for the DME relay allowed the car to start again and run normally so I highly suspect that the ignition switch is also becoming faulty.

Spokes

If the car is "hunting" for its normal idle speed I would also pull out the IVC and clean it. Lots of DIY if you do a search.

bw-porsche

Spokes - Think you mean the ICV or to give it’s full title the Idle Control Valve?

Spokes

Correct.

Ale_72

Soooo, back.
This morning I went for a"courtesy" drive with the new owner of the car (the original guy who bought mine just sold it the same day making some profit out of that )
Unfortunately (or fortunately) there was not too much to be tested/checked.
The car was driving smoothly as always (until when I owned it).
Only thing I noticed is that this new owner had the "bad" habit of pressing the gas pedal while switching it on and bringing the car a little bit up with RPM, around 1.500 before lifting the gas pedal.
Now... I always started the car with no gas at all, just putting the car in neutral and pressing the clutch pedal. I am wondering if his behaviour could "confuse" the car in terms of idle RPM to be kept (forgive my miserable English)

Rocket Rob

I too have found the 964's like to start without any gas pedal. Just let the DME and ICV control the start.