1994 Buick LeSabre
Engine misfires/chuggles at part throttle and light load (about 60 mph). Has
good acceleration/performance otherwise.
P1406 History code.
Scan tool shows EGR Actual % swings wildly when the chuggle happens but the
EGR Desired is steady..
Engine runs great when EGR is unplugged.
Tried a new EGR valve and it didn't fix the problem.
Intake manifold vacuum is high and steady when EGR is disconnected.
I could use some suggestions!!!!
the pcm is the Powertrain Control Module..
I had one about 2 months ago doing the same thing.. the pcm would activate
and pulse the egr valve even though there was no request...Went totally
nuts... If you want more info, post and I can give you pinouts, and voltage
checks when I get back to work monday...
Thanks for the suggestions guys!
I hope it's not the PCM but not hard to replace if it is. I didn't see any
carbon in the ports so that isn't the problem.
Robert, the actual value stays close to desired until the engine starts to
run rough then it swings wildly. I replaced the EGR with a new GM valve and
it did the same thing. Again, the engine runs really good with the EGR valve
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