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Registered
Join Date: Aug 2009
Posts: 3
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Rough Idle
I have an 85.5 NA 944 and it idles rough and is a little harder to start after the engine is warm. If left overnite, it starts right up and idles great, however a ten minute ride to the store and it is rough after start-up. The rough idle goes away as soon as I move the car 30 feet. Any ideas? Thanks.
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08-03-2009, 10:54 AM
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Certified Rennwerker
Join Date: Oct 2002
Location: Kansas
Posts: 1,906
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Look for a vacuum leak first then read up on the idle stabilization valve....aka ISV. See how that plays out then we can go further into other areas to check.
Dal
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PCA " I've been everywhere, done everything......just can't remember any of it!" 
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08-03-2009, 12:18 PM
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Proprietoristicly Refined
Join Date: Jul 2001
Location: ~Carefree Highway~
Posts: 5,833
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I agree with 924Sman
The hoses to the ISV crack at the bends. The ISV/ICV (some call it the idle control valve) can be cleaned and replaced. Hoses are under intake and hard to get to. You should plan to remove the intake and do it all at once. Get intake gaskets. Get new nonperforated screw clamps or fuel injection hose clamps to replace the factory pinch clamps. Get new injector kits and do a DIY clean on the injectors. See tech info center above ^^. Change your AOS seals when the intake is off/ The ISV/ICV rubber mounts also deterioate and you should replace. Get a new Lindsay Racing vacumm kit to finish the job. The big intake "J" tube has nipples on the bottom that rot-replace. Mark all hoses and vacuum hoses. While the intake is off regap the speed and reference sensors--lots of room. Less than a days work if all parts are available and you have repaired many idle problems. GL John_AZ. 1988 924S + 1987 924S |
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08-03-2009, 05:23 PM
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Registered
Join Date: Aug 2009
Posts: 3
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Thanks guys for the info. Would either of you have a link to a schematic so I would know what I'm getting into? I've only had the car for @ a month and have not really gotten the chance to get my hands dirty in it yet. Thanks for taking the time out of your day to help me.
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08-05-2009, 07:31 PM
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Sully
Join Date: Aug 2009
Location: Spotsy, VA- USA
Posts: 18
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I have the same problem with my car (same model and year, also NA) but it does it all the time hot/cold/rain/snow...whenever. I replaced the Ignition Relay and it went away. But after a few starts it came back.
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08-05-2009, 08:07 PM
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Professional Bull5hiter
Join Date: Mar 2008
Location: Alice Springs, Australia
Posts: 8,889
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Suspect the engine temp sensor for the DME if it's idle is okay for a cold engine.
Cheers
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Jeff 83 944 Guards Red 23 718 GT Silver |
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08-05-2009, 08:19 PM
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