mr. bojangles
New member
Hi all. I have a 1997 Pontiac Sunfire with the 2.4L Twin Cam, and a 4T40E 4-speed automatic transmisison. The other day, my car started running rich. Every injector is sending way too much fuel into every cylinder, so much that fuel is getting in the intake and some comes out the exhuast (which is straight piped for now because the catalytic converter is bad). When I try to start the car, I have to hold the gas pedal to the floor, and it runs rough the entire time. If I run it long enough, I get a P0300 cel. When I let off the gas, the engine stalls. After that occurs, I can unplug the fuel pump relay, start the car normally, and the car will run okay until all the extra fuel in the cylinders is gone, and the car dies again. The spark plugs are new AC Delco's, the coil pack housing is in good shape, and I have tested the map sensor, ect sensor, and numerous other sensors. All vacuum hoses are in good condidtion. The battery is new, and the grounds/contacts are all clean. The fuel pump and sending unit are new, as is the fuel filter, injector o-rings, fuel pressure regulator, etc. The timing is set correctly. I read that the ignition control module, coils, or possibly the pcm itself, could be bad. I could use any advice or suggestions you may have. Thanks for reading, looking forward to a solution hopefully!
My first thought would have been the fuel pressure regulator, second would be the map sensor. So that being said , the last time I ran into a problem like that it was a pinched wire in the fuel inj harness. It wasback feedingg to the computer and keeping the injectors on full swing. The other possibility I can think of is the possibly a kinked fuel pressure return line, or a stuck open egr valve but the egr valve doesn't typically cause that much over fueling, Poss. computer also.