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Odd idle behavior

Had a very weird experience today with the Saab (1995 9000CS LPT 92K miles). I had checked everything including the oil before I left to do some last minute grocery shopping. Everything was fine. On the way to the store, car ran great. Came out and started the car and it was very rough on idle. It stayed that way all the way home. Everytime I came to a stop, it would start jerking. The tach would flip rapidly between 1500 and 2000 and the MPG indicator would go between

0 and 10. Made another stop and this time when I started the car it purred like a kitten. Ran smooth and perfectly normal the rest of the way home. Any theories? Is this an indication that something is on its last legs or was it just grumpy? DI was replaced at 70,000.

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Reply to
LauraK
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Intermittent nature points to bad electrical connection - maybe within the DI, maybe the DI plug, maybe the AMM plug, or a number of others.

If I were you, I'd take a good look around, pull off all the main connectors one by one, spray with WD, and push firmly back on. See if it does it again.

Reply to
Grunff

High rpm could be caused by a vacuum leak. Examine hoses for splits and listen for air leak noises in the engine bay.

Reply to
Johannes H Andersen

...happened to me too. Problem in my case was idle air control valve. Before replacing suggest remove valve, give it a good clean with whatever takes your fancy (some say petrol, others white spirit, or injector cleaner, or....). Did this about 12 months ago. Problem was initially made slightly worse, but was advised to lube lightly (e.g. WD40). Did this - been OK since. Car is '96 9000 2.3LPT - 132K miles. Give it a go before replacing the valve - it's not cheap.

Tim H.

Reply to
Pidgeonpost

...happened to me too. Problem in my case was idle air control valve. Before replacing suggest remove valve, give it a good clean with whatever takes your fancy (some say petrol, others white spirit, or injector cleaner, or....). Did this about 12 months ago. Problem was initially made slightly worse, but was advised to lube lightly (e.g. WD40). Did this - been OK since. Car is '96 9000 2.3LPT - 132K miles. Give it a go before replacing the valve - it's not cheap.

Tim H.

Reply to
Pidgeonpost

Yes, good point. I changed the AIV on my 93' 9000 21.0 LPT 5 years ago, but it was probably OK. Never had problems with the AIV since. Logically, it shouldn't get contaminated if the inlet air is properly filtered and there is no leaks.

Reply to
Johannes H Andersen

Thanks for all the suggestions. I'll try them out as soon as the weather warms up a bit which it is supposed to do this weekend. It's still doing it. It's revving high at idle and in first. It sounds like the idle control valve may be the problem. I thought it might be some bad gas. The problem started right after I bought gas at a discount station. I put some injector cleaner in tonight and it seemed to help a little bit.

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Reply to
LauraK

I'm new to Saabs but a Volvo 850 did this. I sprayed throttle body cleaner in to the throttle body and this resolved the problem. May be the throttle body needs a good clean.

Tony Ottawa

Reply to
Tony Curran

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