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-   -   hot restart idle problem (http://forums.pelicanparts.com/porsche-911-technical-forum/290238-hot-restart-idle-problem.html)

jerhic 06-25-2006 02:36 PM

hot restart idle problem
 
its 110* deg today. After a short visit at work i restarted my 82 sc 3.0 an the idle would go from 100 rpm's to 1,200 rpm's! this lasted for about two minutes then it was back to normal stop idle speeds (850rpm).
cold starts are perfect, but once it gets some heat i have a problem. reminds me of vapor lock in some ways.????

Paulporsche 06-26-2006 07:04 AM

Did this happen just this one time?

Have you checked your control pressures?

Scott R 06-26-2006 07:31 AM

I have the same problem, I don't have a solution but I can tell that on mine when this is happening the mnixture is down in the negative numbers, like -0.4 on my gas tester. If you rich it up to say .8 .9 it's fine again, however the base mixture is now messed up.

jerhic 06-26-2006 08:13 AM

Scott, thats what i have done also. i know that theres a problem somewhere and i hate bandaids.
Paul, this has happend several times before, but only when its quite hot out. once past the two minute or so the car runs great! i had my cis checked by a very well know p-car shop. they reported no problem with the settings or pressures.

Scott R 06-26-2006 08:19 AM

Quote:

Originally posted by jerhic
Scott, thats what i have done also. i know that theres a problem somewhere and i hate bandaids.
Paul, this has happend several times before, but only when its quite hot out. once past the two minute or so the car runs great! i had my cis checked by a very well know p-car shop. they reported no problem with the settings or pressures.

I have the same report, all pressures and systems check out. Only difference is that mine is a constant issue, it started out as a random thing. I hope you get it solved, I'm going EFI today, wife says buy it before you lose your mind. :)

bigchillcar 06-26-2006 09:36 AM

rich mixture will cause a hunting idle. on a 110 degree day, the air is particularly 'thin' and artificially cause a rich mixture. bet it doesn't do this on a cool day. how old is your o2 sensor?
ryan

jerhic 06-26-2006 09:44 AM

Ryan, your right about the cool/cold daze. its just the VERY hot days that give me this problem. seems to me that if everything was working properly, the car would adjust for warm and cold conditions and this problem would not happen. the o2 sensor is 2 years old and it was (oem bosch) not a cheep one.

Scott R 06-26-2006 09:47 AM

I'll also add that I just replaced my fuel pump and acumulator per my mechanics suggestion to try and resolve this, however the problem persists. My p-car wrench tried to adjust things up to correct this, but no luck.

I have a goofy theory that my CIS-K computer gets hot and some of the solder traces work loose and start cause issues. However with no diag port I can't find a way to diagnose it.

bigchillcar 06-26-2006 09:48 AM

yeah, you shouldn't have to 'manually' adjust your mixture on hot hot days..it does sound mixture-related for sure, with some component of your fuel injection system not compensating properly.
ryan


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