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My 89 does not idle down.


Bobbyg
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From the title, it sounds like you have a specific problem. What indicates you need a computer (ECM)? We need more detail to be able to offer good suggestions. Do you know how to access the onboard diagnostics?

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Actually that is just one of several computers but sounds more like a stuck IAC (common GM acronym is in the front of the service manual).

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All I know is my mechanic indicates a computer problem since he has tried everything else

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There are many answers and tutorials in the "how to" guides and diagnostics at the top of this page. Key to this is being able to access the onboard systems which is also in the guides. If you can do that, many questions can be answered, right from the comfort of the drivers seat.

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"he has tried everything else" that statement alone would scare me. Do either of you have the factory service manual and/or an ALDL scanner ?

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Fast idle has been caused by the TPS several times. And a time or two by the power steering switch on the rack and pinion.

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Nice thing about TunerPro RT is the data-logging feature. Can set to log TPS and IAC (most likely problems) plus many other things on an ALDL system and drive until it happens, then review "what".. Can get an ALDL to USB adapter from Moates.Net.

 

There is no substitute for proper instrumentation.

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