85-944 rough running when cold
 

My 85 944 idles low and shakes bad when cold.
So I keep at about 1400 rpm when hot so it stays up around 900 when cold.When warmed up I can adjust it to 900 but when cold it runs real rough.Could it be the idle circuit when it reaches the throttle position switch,or clogged injector or----- anybody have any ideas?
Thanks
Doug

Hi Doug,

If your car is a early 85 check the aux. air reg. If your car is a late 85 check the idle stabelizer. The thottle swich would not cause is symtem.

Good Luck,
Lee

The aux air reg should open up when cold right? I think I took a look at it but it is real tough to get to, under the manifold. I will take another look after I get back from the IRL race in Dallas.
Thanks - IT helps to get other input so I stay on the right track.
Doug

The auxillary air regulator is normally open, this allows extra air past the throttle body to boost cold idle speed (or maintain it) it closes due to engine heat and ahet from the electric element withen the unit.

I have a 77 924, it has a similiar problem. I went thru & did a complete engine check. I finally broke down & took it to a mechanic. It was determined that the problem is weak valves. When the car warms up everything expands and the valves seal a little better allowing better compression. I still have to replace the springs & seals but atleast it runs. Start out by checking the condition of the spark plugs after the car has sat over night. If there is any oil or soot on a plug, chances are a bad seal, guide, or other problem with the valves.

Not sure, but as far as valves go! Do a compression check.( all spark plugs out, with open throttle ). Record reading. Then put some oil in the compression chambers ( not to much,just a tsp. full ) and do it again. ( when the engine is cold!!! )Compare Reading. If reading incerese alot then piston rings are bad, if not valves may be the problem (likey). Now warm up engine (hot) , do it again. If reading are 30 to 40 psi higher then you know you have bad rings and pistons.
Good Luck, Jody

Is your problem a rough idle, or a strong vibration? I have the latter problem, and I've read and been told by the Porsche mechanic that the problem is most likely the motor mount "shocks". The rubber motor mounts are liquid-filled, and tend to leak and lose effectiveness when they get this old.

If the mounts are bad, replace them with new 944 Turbo mounts, which last longer. Check the 944 FAQ to see if this sounds like your problem.

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tadrow@usa.net
1985/1 944
"So this is what driving is supposed to be like!"