'93 Saab 900S Rough Idle

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charlieontheradio@gmail.com - 26 Nov 2007 13:20 GMT

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?

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Adrian - 26 Nov 2007 13:43 GMT

charlieontheradio (charlieontheradio@gmail.com) gurgled happily, sounding
much like they were saying:

> I have posted before with my issues to great success on this forum.
> Thank you all for your help!
[quoted text clipped - 7 lines]
>
> Thoughts?

'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, <shrug>.

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Fred W - 26 Nov 2007 15:49 GMT

> charlieontheradio (charlieontheradio@gmail.com) gurgled happily, sounding
> much like they were saying:
[quoted text clipped - 26 lines]
>
> If it's an NG900, <shrug>.

...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.

Signature

-Fred W

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charlieontheradio@gmail.com - 27 Nov 2007 21:15 GMT

> > charlieontheradio (charlieonthera...@gmail.com) gurgled happily, sounding
> > much like they were saying:
[quoted text clipped - 36 lines]
> --
> -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...

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