Taubr Unit

iTrader: (32)

Its my buddys car, its a '02 ta. First off the car is running like crap, cant spin tires off the line, only chirps them. So car has a big power loss. He went to autozone for a scan and it shows bad o2's. Bought new corvette o2's for his longtubes. Car ran ***** out for a few hours then went back to crap again. If you unplug the PCM it runs good again then back to crap in a few hours. We tried our buddys PCM out of his 02 camaro and it does the same thing, so not a PCM problem. Tired a new MAF, same. Tried 3 sets of o2's, same. Tested for vaccum leaks or cracked intake, nothing. Scaned it again and the MAP was reading like 150, real high. Replaced the MAP sensor, same thing. Anther hint is when he starts the car it cranks for a long time without starting but fires up on the 2nd/3rd try. ALWAYS does that too. Hes got a 255 in-tank pump in it, brand new. Car is a stock long block with just longtubes on it, CAI, stall, gears. Nothing major to mess anything up. Car ran good as hell, pullin wheels 5 inches and now it cant even spin the tires. And it just all of a sudden happened. Talked to some speed shops and they just say "good luck man", no help at all. Anything else we can check or look for???

SSpdDmon

iTrader: (10)

If you can hook it up to a scanner (like EFI Live Flashscan) and log some data, then we might be able to help you out. Coming in here and asking us to guess isn't going to get you anywhere - especially when it can be something mechanical like the fuel pump (even though it's new), a wiring issue (maybe with the fuel pump, a loose ground, etc.), a bad sensor, etc. The list of 'what could it be?' goes on...

Taubr Unit

iTrader: (32)

that i understand. There would be no way to get a efilive scan done unless a shop does it and they want $100 to do so. So i posted it up so maby someone else can just type in there 2 cents on it and its free and only takes a few seconds. I know you cant pin point it but just other things we could check that were not thinking of.

Ralls

iTrader: (32)

The MAP is seeing 150 what.. mV?
Either check every sensor or get a scan tool to see them all at once. Your TPS, MAF, and MAP should have very close voltage readings. What's the IAC reading? I would check the EGR aswell. It could be stuck open on WOT and be killing his power.. if it still has it.

Taubr Unit

iTrader: (32)

yea, his car still has EGR on it with no cats. The rear o2's were deleted out of the computer or set to 0 which ever way it is. What should all the sensors be at or close to?

And i dunno how he figured it out but hes running rich at idle and lean at WOT also.

2001NBMZ28

What are the actual codes? Just because auto zone sees an 02 code issue doesn't necessarily mean that's the problem, especially both at the same time - they might be doing what they're supposed to do. Something easy to check would be the ENG SEN fuse. I'd also check the fuel pressure.

BeemerZ28

iTrader: (5)

kinda sounds like a fueling issue to me also. Who installed the new fuel pump?
You said its always been hard to start? This kinda makes me think you should look at fuel system also, maybe the injectors need to be cleaned. Have you pulled the plugs and tried to read them to maybe see if the is a cylinder thats running super rich or lean?

And if I am not mistaken I thought that the 02' didnt have EGR from the factory only AIR pump/smog pump that kicks on when the engine is not warm.

Taubr Unit

iTrader: (32)

exactely what were thinking, theres something else goin on to foul out the o2's. Not sure what codes they are cause i wasnt there. Im not sure how long after the fuel pump install it was when the car started to not start all the time. What fuel pressure should it be at on idle and when its just priming before start-up?

I dont know if it has EGR eaither, i got a '94 so im not sure, lol.

01'WS6

Check fuel pressure.

Ralls

iTrader: (32)

What the sensors should be close to.. well it depends on a few things. At idle TPS, MAF, and MAP are about 0.5v. And at 4.5v at WOT. The IAC should be like 1.8V (85*F or close to whatever outside temp is). Check the ECT too. ECT should be 4.5v cold and 2v (185*F, not sure if it has a lower degree stat or not). I know you all don't want to spend money to scan it, but it will show a lot more sensors than you can check.

ls1_doc

iTrader: (6)

I would say check fuel pressure as well because of the hard start but then i would ask why it ran so good with the new 02 sensors ? Have him get the car re-scanned and find out what codes they are for sure. That will help. It could be something really dumb.

wait4me

iTrader: (10)

If he has headers make sure he checks the wiring on the o2 extensions he used. they might not be correct. so the car will tune itself oposite of correct

2001NBMZ28

With the key just turned on fuel pressure should be 55-60, if it's higher than that look for a return problem.

Doc

iTrader: (9)

Hmm, car with longtubes that runs ok when you reset the pcm? I'd start with the classic exhaust leak(s) check. Especially around the header collector area, within +/-12 inches of the O2 sensors. Note, it doesn't have to be a massive leak, look for exhaust whisp trails on the piping.

With a fresh reset of the pcm's fuel trims the car works fine but, "back to crap in a few hours," suggests an O2 is sensing free air (leak) and adding massive amounts of fuel.

I can't believe there is no fellow LS1tech member in ChiTown that won't give up a little time to help you out. Have you posted this in the regional forum?

phildo

iTrader: (7)

Great suggestion. Seen this many times.
Also check fuel pressure. Sounds like you might have multiple problems. If you installed a E-bay Wahlboro pump the check valves in the pumps go bad and they bleed all the pressure and fuel out of the lines the moment you shut the engine off. So it takes a couple of prime cycles to get pressure up. Also for some reason the pressure has been higher with these pumps which knocks the tune way off.

edcmat-l1

iTrader: (10)

Was there any work done to it recently, that might help narrow it down? You know, "right after we did this, it started doing this".
Also, I've seen crossed 02s do some funky stuff at idle. Not really a huge power loss, but def make em run rough.

cerino2000

iTrader: (1)

I'm voting fuel pressure as well.

Shaarky

iTrader: (37)

when you say its hard to start, then only my opinion would be cam sensor.