'93 Saab 900S Rough Idle

I have posted before with my issues to great success on this forum. Thank you all for your help!

I am still having an issue with a rough idle on my automatic 900S. The car shakes so badly at idle that it's more of a vibration than anything. The RPMs are staying steady right around 1K.

I recently had a "tune up" done, replacing filters, fluids, etc. but that didn't alleviate the rough idle problem.

Thoughts?

Reply to
charlieontheradio
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charlieontheradio ( snipped-for-privacy@gmail.com) gurgled happily, sounding much like they were saying:

'93 could be one of the last c900s or one of the first NG900s.

If it's a c900, then check all the vacuum hoses. No, soddit. Go one better than checking them. Replace them all with 3mm silicone hose. Not expensive, and will solve the majority of crappy idle problems. I bought

5m, from memory, and had more than enough to do my turbo. If yours is a non-turbo, then you won't even need that much. It also wouldn't be a bad idea to take the idle air control valve off and give it a damn good clean- out with aerosol carb cleaner. That's the roughly cylindrical thingummy around the front left of the cam cover, two big rubber hoses heading to the inlet manifold.

It should idle *much* smoother after that.

If it's an NG900, .

Reply to
Adrian

...if it's an NG900 then same advice applies.

One question though, is this a car with an automatic transmission? If so, how is the idle in neutral or park? I've had a couple of SAABs with auto boxes and they all idled rather rough in gear. Ran great otherwise so I lived with it.

Reply to
Fred W

Thanks for all the info!

Some clarifications I realised I should have made after posting: Yes! It's a C900. Convertible, no less. No GM/Vauxhall here. Yes! It is an automatic. Idles smoothly in Neutral, better in Park, shakes like the San Andreas in Drive at a full stop. There's also a brief high-frequency whir when I accelerate from a full stop.

All of my fluids are in good condition and topped off, though my transmission fluid looked on the full side when I checked the dipstick.

I agree Fred W.: It's more of a nuisance than a problem, but is unsettling for passengers and I'm pretty sure is rattling things loose. More than anything, I was concerned that I was sitting on a failing transmission. Once I got the acceleration problem sorted, I wasn't as concerned about it, but still want to make sure...

Reply to
charlieontheradio

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