Dealing with my mom's 00 3.8 firebird right now. It was running pretty bad (85k miles) so about 3 months ago I did plugs/wires and then it ran great up until now. It started not shifting until around 5000 rpms and when you stomped it it would not even go. It would not downshift correctly, just felt really gutless. Scanned it with the Tech2 at the dealer (friend works there) and it threw a code for all 3 o2 sensors! I replaced em all (220 bucks at GM employee cost), and it didnt throw any codes. I drove it personally for about 10 miles back to my mom's office so I could trade her cars back and it was fine. On her way home it did after about 20 miles (almost home) one time and threw a code. Drove it back and scanned it, it was low voltage bank 1 sensor 1 o2. I thought it might just have been a small burp, so i reset it. It hasnt thrown a code yet, but she called me and said it did it once when the motor was warmed up (wouldnt shift, gutless feeling). Any suggestions? No codes, 02 sensors are reading ok (rich lean), numbers are fine in open ane closed.

 

I would be checking the cat converter. could be cauing the 02 trouble as well and the shifting issue

 

That was actually the first thing I checked, and the muffler shop said it was flowing fine???

 

Although you've changed your sensors, I've heard of several cases where bad O2 sensors send no code to the computer, meaning no SES light however the O2 sensors still are bad. When it comes to those little bugger's no code don't mean nothing. Also just a suggestion... check to see how much transmission fluid she has, my car had some wierd transmission issues that faded when I gave it two quarts...

 

Tranny fluid level is perfect. I am gonna do a flush/filter on the tranny this weekend probably. We checked the o2's and they were in spec on the scanner, but I might change out the one that threw the initial burp code, since I can warranty it.

 

did the shop run a back pressure test? thats theonly real good way to know for sure. sticking your hand on the exhaust or hitting the converter are just guesses

 

I think they just looked at it and said it was fine to tell ya the truth. I would almost swear thats its the cat the more it does this crap. My 85 305 camaro did almost the same thing before I gutted the cat.

 

Update.

After 30 mins of driving or so it begins acting up. It will not accelerate for anything and will only get moving if you floor it. Massive hesitation.

I rode around with the tech2 in while it was hot. Codes were all 3 o2 sensor voltages and a lean bank 1 code. The main tech at the dealer said its starving for fuel. We drove it around and did some WOT accelerations (wouldnt really work well since it was hesitating). The o2 readings were going to zero on bank 1 and 8 on bank 2. That should say that its not getting enough fuel correct?

I changed the fuel filter 1000 miles ago so its not that. I am about to go run it around with a fuel pressure gauge in the cowl panel and see if it will tell me more. What should the fuel pressure be on a 00 3.8?

Thanks

 

update again.

Its stumbling horribly now, will not pull out in traffic, only moves at WOT. SES light flashed at me once which means serious misfire.

I am still getting codes for all the o2 voltages and a lean code.

Checked the fuel pump. key on, 40psi. running at idle, 40psi, WOT 45-47psi.

Specs are 48-55 with ignition on, right?

Any other suggestions on what to look at?

 

I'm not the expert on these things but your fuel preasure doesn't sound bad enough to cause THAT...

You MAY have bad injectors... try some injector cleaner and see if that helps...When the car is cool, just make a quick check and make sure all the wires are properly over the plugs... Does the PCM give any codes?

 

Errors come up on the computer as.....o2 bank 1 sensor 1 voltage, o2 bank 2 sensor 2 voltage, bank 1 lean, but the funny thing is NO misfires reported.

 

Sounds like your O2 sensors arn't getting enough voltage which causes them to malfunction... probably a wiring problem. If all your O2 sensors arn't working properly then the computer gets sent the wrong codes for ignition sequences (explenation for your crappy acceleration) and there's a high probability that you're hella running rich if thats true. Your car probably isn't exactly misfiring but is probably just barely getting enough ignition to move. If your O2 sensors is the cause of this then it will eventually get so bad that your car gets to the point where it eventually won't even start...

If you still consider your car drivable, try this as an experiment... fill your tank up and reset the trip odometer... see how many miles you get to a tank...I can get about 320 on average, If you get V8-ish miles then you're definately running rich.

Best luck to ya and hope this helps...

 

It has gotten so bad that it is not drivable. A buddy of mine is a mechanic and i left it in his hands. I was tired of dealing with it already *LOL*. I will report back to see what the problem was.