My 2001 Pontiac Montana w/188000kms. is running rough intermittently.it seems to be worse when the engine is warm and I notice it most at about 60 to 80 km/h. I have changed the spark plugs and the head gasket and intake gaskets where done about 10000kms. ago,what could be the problem?
It could be a fuel issue or an air issue. There are so many different things it could be based on the symptoms. I would start with the fuel filter, if it contains trash it will restrict the flow of fuel to the engine especilly at higher RPM's when the engine need's it. Also, if the injectors are dirty they could restrict fuel also. If you have a leak in the intake manifold this would cause erratic running at higher RPM's also. Sometimes they are installed incorrectly. You can check this by letting the engine idle, have someone lightly press the accelerator (while it's in park of course) while you either spray ether or if you smoke, you can blow smoke into the engine bay near the intake and see if it's sucking the smoke up from some other spot rather than where it should be. Basically something foggy so you can see it being vacuumed from a leaky spot. This will even let you know if you have a vacuum leak. If all else fails try adding two small bottles of Lucas to your gas tank. It works wonders! Worth a shot.
Testimonial: "I changed the fuel filter and added about 1/3 of a 946ml bottle of lucas fuel inj. cleaner. it seems to be better but not completely fixed when you said add two small bottles of lucas what size bottles would that be.I have not checked the air intake yet so i guess i will try that next,I was also wondering if it could be electrical like spark plug wires or coils? because one time a while ago my my check eng light was flashing but just for a little bit. I also hooked up a diagnostic tool after that and no error codes showed up but I think flashing eng light means misfire so thats why I was thinking electrical what do you think?"
SOURCE: Changing intake gasket on a 3.4
yes we do them they take a little longer but you canand it would be easier then pulling the motor to do it
SOURCE: Check Engine Light on and flashing on Montana 2001
Most major Autoparts stores will get the Diagnostic codes from car computer and give you info on why light is on and what the problem is.
SOURCE: Check Engine Light on and flashing on Montana 2001
MThe problem is most likely the catalystic converter.ost
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