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1988 Cadillac Sedan DeVille 4.5 FWD 111,XXX miles
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40 Posts
Discussion Starter · #1 ·
Hey guys, I've got an 88 DeVille that has an inconsistant idle mostly noticeable with the a/c on and a very noticeable bog down when accelerating from a stop. I have no lights or codes indicating any issues. I just had the motor rebuilt 3,000 miles ago and otherwise drives great. Also, I didn't find any vacuum leaks. Any ideas?
 

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85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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773 Posts
I would check the normal stuff like air filter, Cat converter, fuel pressure etc. Has it run this way since the rebuild? If so, I would recheck the timing. The ignition timing must be set with an assembly line diagnostic connector pin shorted. This causes the distributor to bypass the EST computer controlled ignition timing mode and reverts to internal distributor timing. If you try to set the timing without doing this, The timing will be way off.

A factory service manual will be of great help here. They have excellent diagnostic trees for finding problems like. Will save you lots of time and money chasing dead ends.

There are also a lot more diagnostics available than just pulling codes. You can for instance watch the operation of the oxygen sensor to see if it is functioning correctly. (will keep you from replacing it unnecessary)
 
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