I have a 1989 Firebird with the 2.8 and a 5 speed. It is running super rich (like eyes watering rich) to the point it will barely run. I pulled the plugs, cleaning them and and regapped them. New cap and rotor and basically new spark plug wires. Originally I thought it was running bad due to a spark plug wire that has fallen on the exhaust manifold and burnt through in a small area, so I replaced that and went to drive it and it would barely accelerate up a hill. It also doesn't sound like it is running right, either. I hook it up and did some data logging with TunerPro and it seems I may have a couple things that aren't right.

First, it is running in Open Loop mode, BLMs in the 140s, Oxygen sensor is reading mostly "Lean", but since it's in open loop, it should be ignoring that.

I also suspect my O2 sensor is dead, probably due to the rich condition.

What could cause it to run so rich with so high of BLMs at idle?

Thanks,
Douglas

 

Anybody? I forgot to add, the injector pulse width was ~ 5ms at idle. Any thoughts on why my car feels it needs to just dump fuel in at idle?

 

Exhaust clogged anywhere? Like the cat?

MY cat broke internal and shifted sideways inside. I could do 30mph max with my foot to the floor and it was very rich out the tail pipe.

 

Have you checked the injectors?

 

Check the resistance of the CTS when cold and then check the film inside the MAF to make sure it's flat. The CTS may not be setting a code but be out of spec, and I've had MAF sensors fail without coding before. Both will throw fuel into the mix.

 

if it fouled the plugs dont clean them just replace them, acdelco standard plugs are by the the best r42 or r43tsk's. once u do that unplug the o2 and see how it runs, also check the fpr to make sure the diapghram didnt tear

 

I'm not sure why that would have the car running super rich at idle, it should effect any of the sensors that in open loop would tell it to run rich.

No, I have not. That was my #1 thought until I checked the datalogging and found that the computer was commanding a rich condition.

I will check those. With the MAF failure wouldn't I see it in the data logging with the grams/sec? Anyone know what it should be at idle? It was around 50, irrc, and went up when I revved the motor. I will check the CTS.

Good thought on unplugging the O2. I plan on replacing the plugs once I get it sorted out, however it seemed silly to be replacing them when I know the car is dumping fuel in just to foul them again. I will also check the FPR, but I wouldn't think that failing would cause the computer to command it to run rich.

Thanks,
Douglas

 

whens the last time u changed the air filter? plugged filter will make rich condition every time

 

Went out and played with the car more today. Unplugged the MAF, didn't help it run any better and oddly enough... the car realised the MAF was unplugged however in the ALDL values the g/sec would go up and down when I revved it. So I then plugged it back in and unplugged the O2 sensor. That seemed to make a difference, however not once did the car's BLM change from 143.

I just wish the car had better data logging... it just doesn't give enough info and some of it is weird (like the MAF g/sec values changing even when the MAF is unplugged). Also, I noticed that INT never changes. The O2 sensor value also was there but for some reasons the "switches" value kept going up and down, even with the 02 sensor unplugged. I am really about it just get my 91 Formly going and park the V6 and prep it for a hybrid swap. At least then I'll be replacing basically everything in the fuel/ignition system.

 

IIRC, according to the FSM, the MAF should be between 32-150 gm/sec, between idle and WOT. If the MAF is reading high, it will run rich. I know that when I replaced my last one, it was reading some 30% higher than it should have, but without tossing out code 33 (until the last minute before it got chucked).

Did you check the CTS temp when you were datalogging?

Also check the TPS% and that it's adjusted properly (if adjustable), check between the O2S pigtail and ground for possible grounding of the O2S wiring (need to disconnect the ECM for this). And also check that the tan O2S ground wire on the passenger's side cylinder head is grounded (it's with the black/white ground wire on the lifting eye stud) and clean.