1993 Buick Park Ave Ultra..Missing problem

1993 BUICK PARK AVENUE
214,000 MILES • 6 CYL • FWD • AUTOMATIC
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I have a 1993 Park Ave Ultra Super charger, it keeps missing when you hit 45 then evens out then starts again around 50-60mph. I changed spark plugs, wires, altenator, battery, did fuel injection cleaner, replaced with used coil packs. I am at a loss at what else it could be has a code #56 in the computer. Do you have any suggestions?
Nov 27, 2010 at 4:14 PM
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ERNEST CLARK
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  • 1,730 POSTS
First, NEVER try to hunt down a problem by buying and replacing parts. As you can see, it gets expensive and hardly ever works.

The proper diagnostic procedure is to isolate each system and TEST the components until you find the one at fault. Then replace only that part.

Your Code 56 means the "Quad Driver" your computer uses to send voltages and grounding signals to sensors and other engine components is faulty. This is MOST CERTAINLY your issue.

Not sure if just the driver can be replaced or if your computer must be replaced. But these buick computers were definitely prone to failure. Sorry.
Nov 27, 2010 at 4:21 PM
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