| |
Jim Grant's Tech Tips
88
Chevy Blazer, Light Throttle Chugging
Q: I own an '88 Chevy
Blazer 350 engine with 110K miles. When I first start it, it runs well,
but as soon as it warm up, and I press lightly on the accelerator it starts
chugging. If I let off the gas it will stall. When I start it back up,
it idles fine but as soon as I put light pressure on the throttle it starts
chugging again. If I put it in neutral and rev it up, before it stalls
it will idle smoothly. I have replaced the oxygen sensor, map sensor,
throttle position sensor, and coolant temperature sensor. This has helped
some but did not cure the problem. Someone suggested replacing the EGR
valve. What would you suggest? Baffled in New Hampshire.
A: The
EGR valve is a possibility but, I wouldn't recommend replacing the EGR
valve on a guess. The simplest way to prove if the EGR valve is a factor
in your stalling problem is to temporarily disable it. If temporarily
disabling the EGR valve corrects your stalling problem then you're headed
in the right direction. But don't replaced the valve yet. Be sure that
the vacuum supply to the EGR valve is correctly routed. Something as simple
as a misdirected vacuum hose can create a myriad of driveability problems
that no replacement part can correct. There is one rule that you should
follow when diagnosing problems such as yours. If you can't prove it's
broken, don't replace it.
|
|
