OK the car

1997 Chevy Cav
2 Door Base model (no ac no pwr anything)
5 Speed
Green (proably doesn't help)
2.2l
360,000km
Compression 170 170 164 171

new plugs, new fuel filter, new air filter (things i have tried or replaced)

THE PROBLEM

OK so i was driving down the highway and went to pass somebody and noticed my car had no power at all, so i stopped and while stopping noticed that i had no throttle responce at all after down shifting for about 5 seconds then i got a very little and this is repeatable every time. The car starts up great. Push the throttle at 25% and you can rev it up to about 4100 rpm then the engine cuts out like your hitting the speed govnernor ( for those who do not go that fast no throttle responce at all till your at a acceptable speed) but the car it cuts responce till 3400 rpm then you can rev it back up to 4000 and so on. if your still using 25% and it will bounce and do that repeatly. IF at any time you go above 25% throttle the engine spudders and almost stalls. As long as i use only 25% throttle the engine has no issue going up a huge hill in the appropiate gear and under 4000 rpm. Which as we all know is the start of the power band in this car. Stumped, I checked all the sensors no visable breaking of wires ect. Replaced the fuel filter, the plugs are new less then 10k on them (old ones were carbon fouled). There is no check engine lights at all none ever came on. I Have had the check engine come on along time ago before i replaced the plugs but it was on then and never again did i see it. the fuel pressure is 40 psi running.

I am thinking based on some snooping the TPS or the Crank sensor. I have also read something about a EGR valve being stuck open could cause this too?? Not really sure. I have no air care and slack emissions up here so if something like bypassing my o2 sensor or blocking off my egr is the fix. I am will to try. The car was a cheap winter beater for when i went back to school. It just turned out to be pretty reliable would like to keep the repair cheap.

Sure sounds like your fuel pump is weak, 40psi running...should be in the mid50s




- 2004 Cavalier - 124k, owned since new

Check the fuel filter. Sounds like it is starving.

May have a bad Catalytic converter. If its clogged it will do what you saying.

Usually a clogged cat will get worse as it gets hotter. A plugged fuel filter will cause the problem to be consistent.

OK so the updates

Replace
Fuel pump
fuel filter
plugs and wires (again)
TPS
Vacume advance system maybe ( vacume lines that go into the manifold all plastic )
The bolt on sensor on the manifold maybe noc sensor
air filter again (was fine)


if it is the cat i could i just cut the exhaust out to test ( or is there another o2 sensor or a sensor that checks for back pressure)

I am kinda at a loss
Since i have done all the new replacements the car is acting like it has a air bubble as well as the previous problems. The car revs up and cuts out on its own. It does not run as ruff though. still no throttle responce and cuts right out at 4k rpm. I am going to go cut the exhaust out and see what happens from there cause a coupling is like 15$

I also suspect the new tps and sensor as nfg * off a parts car that had a blown tranny (sunfire 98 2.2l )

NO Cat only had a resonator and a muffler

the exhaust was pinched a bit cut the thing out just past the engine so straight piped no change in anything it almost seems like the vacume advance or the mass airflow sensor is not working right. Not sure though. Similar problems on my 86 mr2 were a broken vacume line. Not sure but i think that that sensor on the back of the manifold closest to the firewall thats held on by 2 torque screws ( not the TPS) might be the issue i removed it and it was gummed up a bit and it seems to work on some form of vacume but it has no play at all . If somebody could tell me what that was called i might be able to replace it. Not sure my guess would be the Mass airflow sensor. I have not replace the crank sensor yet but was considering it. I think its the cylander like one on the side of the block.


Anything else??? The car runs the same hot or cold. I am getting fuel spark and compress at the cylanders it almost seems like a timing or sensor issue.

OK sensor at the back is the Idle Air Control, From the guru i talked to he said that i should haved started there in the begining cause it will cause alot of my gas smell issues and all my other problems (rough idle, cutting out when throttle is applied due to to much fuel getting put in). As well i should change out the fuel pressure regulator which is connected to that vacume asssemble thats controled by that sensor as it could also be faulty. So i will post back once i get out to my parts car and get those parts off and try them. He also said that 40psi for my fuel pressure was fine that is where is supposed to be cause my car is vacume assisted. 50- 60 psi is for no vacume assisted cars. As well the the car was never starving for fuel my plugs are carbon fouled from running rich and smell like gas as well my car back fires on decel if it was starving it would not reak like gas and backfire like so.

Fuel pressure regulator is what I'm thinking. The knock sensor goes in the block, not the manifold.

I know this thread is 6 years old, but what was the final fix???

haha, good question, on what the final fix was. I was reading it and thinking coil packs or ICM (ignition control module), as i've had that in my 95 sunfire. I know the local parts stores can actually test the ICM, so they can know it's bad before you spend the money on the replacement.

Im having the same problem. I havent checked my cat. Or the ignition control module.

I would almost guaruntee that its jumped time. I had the exact same problems and i tore into mine and found that a timing set had been put in and installed wrong. My crank sprocket was off by two teeth on the timing mark. Here is my thread..

http://www.j-body.org/forums/read.php?f=11&i=171394&t=171394