Unknown stalling problem at idle on my 02 C4S

[Gary S K Lee]

I have searched many forums regarding this issue. I have this problem when the engine is fully heated up it will stall at idle (mostly at stop lights). I have already replaced the MAF sensor and a new egas throttle body but this problem still exists. My garage already checked that there's no vaccum leaks. Is there anything that i might missed?? I heard some ppl say that the ICV (idle control valve) might be bad...

thanks!!!

Edited April 21, 2014 by Gary S K Lee

[Loren]

:welcome:

Your car does not have an ICV. Your car is eGas so it has a sensor instead.

I would start by reading the codes with Durametric, a Porsche PST2, or Porsche PIWIS tester.

This should tell you if you have one or fault codes. The fault codes are the key to diagnosing and repairing or replacing the right parts.

[Gary S K Lee]

the thing is there's no CEL light showed up...

[Loren]

You can still have faults and pending faults - not all of them turn on the CEL.

[Ahsai]

Since your car is egas, it doesn't have an ICV. Also, unlikely it's the ignition switch since it relates to engine temp. I think the first step is to get it scanned with a Porsche scanner such as Durametric for any error codes.

[Gary S K Lee]

i just finished reading this topic about stalling and it has the exact problem as mine. http://www.renntech.org/forums/topic/30839-car-does-not-start-easily-after-stalling/?hl=%2B996+%2Bstalling

could it be a melted down starter cable or a bad battery?? my battery reads slightly above 12volts in ignition switch position 2 and when running it reads slightly below 14volts is that normal?? im so glad i found the exact problem with another C4S.

[Gary S K Lee]

i just read another post mentioning replacing the air filter with k&n might cause the problem??

[Ahsai]

Your voltage reading sounds fine. Yes, if that cable is corroded, you will have a hard time cranking when hot (even with a healthy battery). However, it's not clear to me how a corroded cable makes the car stall at idle though, which seems to be your problem. When you crank the car after stalling, do you feel the starter is struggling (turning slowly) or the engine is spinning at normal speed but it just won't fire up?

The starter cable is behind the alternator. It's a lot of labor to change out since you need to remove the alternator and the a/c compressor, the throttle body, and the T rubber intake plenum.

Edited February 28, 2014 by Ahsai

[Ahsai]

i just read another post mentioning replacing the air filter with k&n might cause the problem??

Do you have stock intake and filter? The oil from K&n filter can ruine the MAF. Aftermarket intake does not work well with the MAF, which is calibrated with the stock intake.

[Gary S K Lee]

yes after stalling it struggles to start i had to crank it 2 or 3 times to start it up and the idle speed would be higher at around 1000rpm.

Yes i have a stock intake with a k&n air filter replacement.

Edited April 21, 2014 by Gary S K Lee

[Ahsai]

If you suspect electrical issues, should also check the ground cable between the engine and the chassis on right side of the engine (hope it's the same in your RHD). Also, a bad crank sensor can also cause hard start with warm engine. However, it should not cause the engine to stall by itself. Again, it's difficult without scanning the car for more clues.

Btw, should also check if coolant temp sensor is giving correct reading.

Edited February 28, 2014 by Ahsai

[Gary S K Lee]

i was informed that the crankshaft sensor is the problem i will have it replaced...

Edited April 21, 2014 by Gary S K Lee

[Gary S K Lee]

recently replaced the crank sensor and it's been running fine so far (fingers crossed)...hopefully the stalling problem won't happen again.

[Ahsai]

Hope that was it.