Rough run when cold

[scintaar]

Hi!
I've got an 88 944s.

When I start her in the mornings, she has a hard time revving clean... starts first time but just won't rev or idle smooth.
I've just changed the plugs and leads in an effort to fix this, but no luck!
Any ideas?
Thanks

[SoCal Driver]

That is 'S' as in 944S? Check for vacuum leaks. Check that the idle control valve (under the intake manifold) is clean. The DME controls the idle directly. When there are vacuum leaks or a bad engine temp sender, the DME over reacts setting the idle levels.

Personally I would be as (or more) concerned with the cam chain and pressure pad and the condition of the timing belts. Should one or the other break it's over $3,000 to fix.

[krahm]

As usual, SoCal is on the money. I would add something else, though. If you're going to cover all the bases, you'll want to pull the intake, replace all the seals (oil separator, dipstick tube, fuel injectors, am I missing anything?) in the vacuum system, the small vacuum lines, tighten up the big vacuum lines and replace anything that looks cracked, replace the intake manifold gasket (obviously), check the flexible portions of the intake system, and (I can't emphasize this enough), while you've got the intake manifold off, pull the fuel injector grounds and clean them/check them for corrosion (I had this problem on my car). Your problem could be related to any of these things, and you've got to have the intake manifold off to do them.

If you haven't pulled the intake before, don't be intimidated. It took me a weekend the first time. I did it in 1/2 an hour last week. Just go easy, don't force anything, watch out that you don't score the mating surfaces of the head or the manifold. While you're at it, you might want to clean the manifold and throttle body with carb cleaner. If there's oil in there, odds are you've had a bad vacuum leak.

Good luck!

[scintaar]

Thanks for the answers!
Re-reading my post, I think I may have given you only a bit of the picture...
she runs great... no hesitation, no rough driving, nothing - once she warms up!
It's just the early mornings that give me grief. she starts, and idles a bit like a six cylinder with a full race cam running carbs! try to drive and she might stall out unless you feather the go pedal.
Pulls like a freight train through all the gears and once she's been started for the day, she seems fine.
We'll be getting the timing done soon, but I was wondering if there was something else I need to address in the meantime.
I'll be going over the hoses again this weekend... maybe I'll find something!

[924Sman]

Well if the above suggestions fail try a new AFM. Had the same issue changed the AFM and it is ok now.

Dal

[Dougster]

Sounds like something all my 944's have done...

I just let her idle for maybe 30 seconds before taking off, but I too have wondered how to lessen the rough early idle...

Mine runs great AFTER warming up too...