93 Cavalier 2.2L OHV I race on dirt tracks...the last race of the season last year I noticed it was bogging down a little when I would get on the gas at low RPMs. Picked up once the RPMs picked up.
Now, after having done some unrelated work on it this offseason, I took it out for a test drive around the block and it is still doing the same thing. I have read that a car running rich can cause this. I have noticed that when I start the car and let it idle for a little, the gas smell seems strong (although I would expect this a little, as the exhaust is cut off from where the cat. converter would be on back, no cat or muffler).
On a fuel-injected car that is computer controlled, what would cause it to run rich? Would running rich cause it to bog down when I hit the gas hard at low RPMs? And if it is running rich, how do I fix it?
well yes, running rich could cause a bog down.
computer controlled cars are going to take input from multiple sensors to get the fuel trim, and you should really diagnose it with whatever scanner can communicate with it. I dont know how much info you can get on an obd 1 car, but check and see that the o2 sensor is switching frequently, and check things likt the tps voltage, etc.
Having the exhaust cut off ahead of the cat will cause that. Your front o2 sensor will be reading the air/fuel ratio as being leaner than what it really is (reversion of outside air back past the o2 sensor). The longer the pipe you add back on, the more accurate the o2 readings will become.
Innovative Tuning
HPTuner Custom Tuning
Superchips Dealer
innovativetuning@rogers.com
innovative_tuning@rogers.com
Shane @ Innovative Tuning wrote:Having the exhaust cut off ahead of the cat will cause that. Your front o2 sensor will be reading the air/fuel ratio as being leaner than what it really is (reversion of outside air back past the o2 sensor). The longer the pipe you add back on, the more accurate the o2 readings will become.
Glad I read that... It sure explains why my mileage has been dropping on my '94 since the tailpipe fell away, leaving the muffler hanging & levering against the rest of the system.
Go beyond the "bolt-on".
Is this the truck you posted about on the HPTuner forum?
Let us know if your MPG's pick up to where you expect them to be after you fix the exhaust.
Innovative Tuning
HPTuner Custom Tuning
Superchips Dealer
innovativetuning@rogers.com
innovative_tuning@rogers.com
Shane @ Innovative Tuning wrote:Is this the truck you posted about on the HPTuner forum?
No, that was a different one.
In fact, Shane... The one I posted about there was supposed to replace the one I just mentioned here. Until the it died just after startup one day in the driveway. That prompted me to check the compression & for bent valves (With just a compression gauge) on the '94 before buying a new chain-set to install. It's run like a champ since. The '99 on the other hand...
I wish I had a garage.
Go beyond the "bolt-on".
Refresh my memory......did that truck have a crank or cam sensor code?
Crank-sensor... And it only appeared once, after sitting overnight through the first heavy rain that it saw in my hands.
Go beyond the "bolt-on".
check your fuel pressure regulator it can be leaking fuel to the vaccume port...... just a sugestion.
http://a709.ac-images.myspacecdn.com/images01/85/l_c45bfa9c54e0aebaf0fbf6bf67c30a74.jpg
I suppose that's possible... I'll check it as so as the weather allows.
Go beyond the "bolt-on".
jon turbo grand am wrote:check your fuel pressure regulator it can be leaking fuel to the vaccume port...... just a sugestion.
Oh wait... That wasn't meant for me, was it?
Go beyond the "bolt-on".
