Having a problem with not maintaining idle speed when letting off throttle. Occurs mostly when warm. When letting off the throttle from 1500rpm up the idle speed drops close to o. May or may not stall. Engine does not idle as smooth as it used to. Ideas?


eworkley
87944s
86930

 

When I was first looking at 944's last December, I drove an '87 944S like yours that these exact symptoms. Consensus on the board was a vacuum leak at some small part, I think just a vacuum hose 'Y'--that typically goes bad--no big deal but it's under the intake manifold and so difficult to get to. HTH

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" /> B

 

eworkley, the other thought is your idle control valve. Its located under the intake manifold on an 8 valve NA, but I think you have the same. And my car behaved the same way when it starting sticking.

When its acting up, try tapping on that canister (its about 3" long, silver, maybe an inch and a half in dimater), and see if things smooth out. If so, its common, they gunk up and cause bad idle. You usually see this problem in cold weather though, when it controls air intake depending on outside air temp.

If it is the culprit, then you got a chore. You have to remove the fuel rail, the airbox, airflow meter, and then the intake manifold to get at it. Some guys here clean them out with success (using carburator cleaner type solvents), but when I gave in, I decided to just replace it with a new one (~$150), so I wouldn't have to go through the hassle again for a while.

 

Does the 944 n/a have an idle stabilizer?

For a turbo...I'd say disable the idle stabilizer (or idle control device) and then set the idle using the idle screw...but I donno if this applies to an n/a.

 

Adrial, like I mentioned, mine ('88 NA) has the idle control valve (stabilizer). Disabling it can cause some vacuum line issues and probably cause the car to run too rich or lean. Haven't heard anyone here actually disabling it, just cleaning or replacing it.

 

I'm gonna take the idle control off and clean it up. It just started doing it last week. Thanks for the replies.

eworkley
87944s
86930

 

[quote]Originally posted by adrial:
<strong>Does the 944 n/a have an idle stabilizer?</strong><hr></blockquote>

Yes, if it is a 1985.5+ car. The earlier cars has a similar device, but I believe it was only used durring warm up.

 

This being an "s" has a mixture of turbo and n/a engineering. Sometimes it creates problems troubleshooting. Any way I've got it apart.....

eworkley
87944s
87930

 

[quote]Originally posted by TomH:
<strong>Adrial, like I mentioned, mine ('88 NA) has the idle control valve (stabilizer). Disabling it can cause some vacuum line issues and probably cause the car to run too rich or lean. Haven't heard anyone here actually disabling it, just cleaning or replacing it.</strong><hr></blockquote>

It's disabled only temporarily to set the idle with the idle screw...

It's disabled (in a turbo again) by jumpering B & C in the test port...again donno if the 944S has one....if it does its by the driver side shock tower.




Hmm I guess I haven't been too usefull...oh well

 

Got it back together...seems as though the throttle return wasn't finding home and tripping the idle switch...cleaned everything...reassembled and adjusted the stop screw...seems to work fine...we'll see...
Thanks for the posts

eworkley
87944s
86930