Re: Vibration at Idle - Saab 900 Bulletin Board -

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Re: Vibration at Idle

Posted by Landjet [Email] (#16) [Profile/Gallery] (more from Landjet) on Fri, 12 Oct 2018 20:12:46 Share Post by Email
In Reply to: Vibration at Idle, OH900, Thu, 11 Oct 2018 18:11:59
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I'm jumping into this thread to revive it where vibration can affect idle and lets see where this goes.

Top vibration things to check though I am sure there are others.

Head gasket replacement -- even with a Saab dealer shop, I was told that 1 in 10 times a tooth off on the timing chain happens. So, i would be looking at the the perfection of the timing marks on the two cams. Had the head gasket not been replaced, I probably wouldn't mention that.

Coil -- corrosion on the contacts -- in fact all the contacts of the electrical system up in the engine bay need to be cleaned, scrapped and connected with a rock solid ground strap, no challenged thick wires. Ground strap to alternator must be thick and well connected.

Fuel injection wiring -- OK, so this was my pivotal moment on my 1989. A rat had chewed one injector wire. I looked at the injector wiring harness, there was a ground that was not solid, the wire strands had been reduced in numbers, it needed to be patched. I put in a new injector wired for the rat modfied one, and patched up the injector grounds, the black wires that connect to the head. The ones that were taken off when the head gasket was done.........INSTANTLY, the engine ran better, no off idle vibrations, etc.

I'd been chasing this problem for years it seems, nothing worked but all the new parts helped, but never cured the vibrations.

So, it could be the really simple things that create the off idle problems -- I've posted on this problem with my 89T but I don't think I ever reported the solution and what finally fixed it.

Good luck and hopefully, you'll find the one stinking thing out of the 27 that makes it run like a sewing machine.

OH, and check the cylinder compression and see if all are even......might do that first.

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