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149 Posts

Posted - 01/20/2013 :  5:57:45 PM  Show Profile  Reply with Quote
I have a 97 Bluebird Chevrolet with a 366 that is giving me fits. I am guessing I have an ECM problem, but let me try to describe what is going on and maybe someone will have something to add.

First, the bus will die after it warms up, it will start up right away, but as soon as it makes a stop or idles down, it will die again. When started from a cold start, sometimes it will run very rich and rough, other times it will run perfect.

Second, it will have random times where it will high idle, like 3000 rpm high idles. This will occur when the bus is cold or warm.

No codes or anything, in fact when I hook my OBDII scanner up, it will power up the scanner, but will not connect to the scanner.

I can't find any place that carries this ECM anymore, so I will have to have it sent off to be rebuilt somewhere.

The fuel filter is new, along the distributor, cap, rotor, coil, plug and wires.

Something else I noticed was when I installed the new distributor. I unhooked the shunt wire to do the timing and it didn't affect anything. Any other time I have timed a 366, when I have that wire disconnected the bus will run horrible until the wire is hooked back up after the timing is set. On this bus it made no difference.

Any ideas???

Senior Member

91 Posts

Posted - 01/22/2013 :  11:48:18 AM  Show Profile  Reply with Quote
Is this bus a TBI unit ? If so check for an intake leak and the IAC motor. A leaky intake gasket will cause the IAC to hunt and do stupid things.

A can of carb cleaner sprayed very close to intake will usually show where the problem is. Had this one on a F.D. truck a few months back.
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2181 Posts

Posted - 01/22/2013 :  12:46:53 PM  Show Profile  Reply with Quote
Check your coolant temp sensor, maybe giving the ecm a false reading.

“The good thing about science is that it's true whether or not you believe in it.”
Neil deGrasse Tyson
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