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 condition. 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!
I can't type in cursive!
These parts were replace at the time of the car started flooding with fuel?. Bes of my knowledge would be, If your'e getting to much fuel into the cyl its more likely Fuel pressure regulator issue. Or Injector problem. Also did u do all the work on replacing the injector O rings? and also coil packs are they original?. Also my other question is are any other codes being displayed besides P0300 codes?.
Jonesey wrote:. he fuel pump and sending unit are new, as is the fuel filter, injector o-rings, fuel pressure regulator
Those parts were replaced not too long before it started flooding, mainly for preventive maintenance reasons. I replaced the fuel injector o-rings myself. For a short time, probably less than a month, the car ran great like it did before I replaced those parts. The P0300 is the only code showing. I am pretty sure that the coils are original. Everybody's first thought seems to be the fuel pressure regulator, so I am probably going to swap the one from my 2.2 Sunfire (same part #) just to check it again to be sure. It seems very strange to me that all injectors are hanging open at the same time, which appears to be what is happening. The funny thing is, my catalytic converter died (due to an unrelated issue, which has since been fixed) so I cut it off and removed the secondary O2 sensor, and put in a piece of straight pipe. Within 3 or so days of running that straight pipe, the car started running the way it is now. I thought removing the second O2 sensor would throw a cel at most, telling me the cat was missing; I didn't think it could cause a rich condition. Could it be possible? I forgot to mention earlier, the primary O2 sensor is in good working condition as well. I also had my ICM tested today, and it is also working fine. I really, really appreciate the feedback! Thanks!!!
I can't type in cursive!
Jonesey wrote:............ The funny thing is, my catalytic converter died (due to an unrelated issue, which has since been fixed) so I cut it off and removed the secondary O2 sensor, and put in a piece of straight pipe. Within 3 or so days of running that straight pipe, the car started running the way it is now. I thought removing the second O2 sensor would throw a cel at most, telling me the cat was missing; I didn't think it could cause a rich condition. Could it be possible? ........
Ding Ding Ding Ding!!!! You just told us what the problem is. Fix it with the proper parts as it should be.
Cause and effect in it's most simply form, "I did this and then that happened".
My 2x anyway.
Dave
Vaccum Lines caused this for a car, i played with it for days untill i figured it out, check the lil' things first i guess.
Fireboy153
Brady Fire Co. - Station 150
Long Live The Sunflower! (yea its not so "cool")
I just about ruined my ls1 because of this, replace the pcm, and it fired right up.....
UPDATE: I installed a mechanical o2 simulator, and a new secondary o2 sensor, in the test pipe. Still no change. Could one of the coils, or the pcm, be bad? I am running out of ideas here!
I can't type in cursive!
By the way, Josh, I did notice your post. I was just wondering if anyone had replaced the pcm on the 2.4 to cure these issues. I really do appreciate your input very much.
I can't type in cursive!
the symptoms alone make it sound like its the fpr. pull the vacuum line off of it and start it up. I've seen the rubber diaphram in there get a hole in it and the gas went through the vacuum line and into the intake manifold to the point where it would pour out when you removed the intake. this was on a ford ranger but still the same principle.
david keevil wrote:Jonesey wrote:............ The funny thing is, my catalytic converter died (due to an unrelated issue, which has since been fixed) so I cut it off and removed the secondary O2 sensor, and put in a piece of straight pipe. Within 3 or so days of running that straight pipe, the car started running the way it is now. I thought removing the second O2 sensor would throw a cel at most, telling me the cat was missing; I didn't think it could cause a rich condition. Could it be possible? ........
Ding Ding Ding Ding!!!! You just told us what the problem is. Fix it with the proper parts as it should be.
Cause and effect in it's most simply form, "I did this and then that happened".
My 2x anyway.
Dave
This is not the problem. The extra fuel may have killed the cat but the removal of the cat and second o2 wont change his fueling. I would lean towards fpr or possibly pre cat o2 for starters.
