lean problem, need help

[OTDlifer]

ok so i have a 97 GS-T with a 2.5 cat back. the other day i installed a 2.5 downpipe and 3" cat. after everything was installed, the car ran really lean, like its hard just to get it into stoch. the exhaust shop that installed it ripped the grounding wire off, so i went back and they put a different one on, but still the same problem. could the ground still be the problem or is this normal and now the car needs to be tuned??? thanks for whatever help i get
Anthony

 

[OTDlifer]

so nobody has any ideas???

 

[gixrman]

looking at you vehicle profile I don't see were you upgraded your injectors. What boost are you running? Are you maxing out the fuel settings on your AFC?

You just free'd up a major restriction in your exhuast, so the old air pump is breathing good which will lean things out.

How do you know its lean? Need more info.........

 

[OTDlifer]

no haven't changed my injectors yet, and haven't changed anything on my SAFC yet either. but as for running lean the air/fuel gauge is all the way on the lean side, i can't even get it to go ouver into the middle or rich, either at idle or when the gas is floored

 

[NewB2dsm]

Ignore your damn A/F gauge its useless other than telling you if your o2 sensor is working.

And with your mods keep the boost around 16psi and dont worry about it, dont touch your afc. get some injectors and frontmount and tune the car.

 

[OTDlifer]

ok but its not even reading the air/fuel mix. only one red bar comes up, instead of running back and forth, plus the car feels like it has less power and using alot more gas for some reason

 

[missouri_dsm]

sounds like your O2 sensor is bad. That would explain the horrible gas mileage and performance loss.

 

[trbotaln]

reset your ecu and drive it for a couple of days to let your car get used to the new parts. Same thing happened to me when I put 3" exhaust and down pipe on my car.

 

[NewB2dsm]

sounds like your O2 sensor is bad. That would explain the horrible gas mileage and performance loss.

im going with this too.

 

[OTDlifer]

ok i already did the disconnect the battery one, and it hasen't done anything yet, i'll let ya know. but about the O2 sensor being bad. do they just break, b/c it was fine. and would it be the front or back, and wouldn't a code pop up for it, b/c it hasen't

 

[gixrman]

your ECU gets most of its info from the front o2 sensor, the second o2 is to see if the cat is working. Do you have a Datalogger, wideband? I hope your not just trying to tune off your A/F gauge.

 

[OTDlifer]

nope don't have either but as for tuning i only tuned the SACF like 6 months ago on a dyno, b/c the mis wasen't right underfull throttle. so is there a way to test the O2 sensors

 

[missouri_dsm]

so is there a way to test the O2 sensors

Well if your a/f gauge is hooked up correctly then it is obviously your O2 sensor. #1. Check to make sure your gauge is hooked up correctly,mainly the signal wire.#2. If everything is hooked up correctly then your O2 sensor is bad or your gauge is bad. #3. If you have access to a voltmeter tap into the O2 sensor wire right next to the sensor, start your car and let it warm up. The voltage should bounce around similar to your O2 gauge. You might have to play with your throttle while watching the voltage. Voltage should go up when you give it the throttle. If not somethings wrong with your O2 sensor.

 

[OTDlifer]

ya i was doing a sensor check off of my SAFC, the sensor #1 was moving all over when i hit the gas, and #2 stayed at .5 so prob that ones bad right???

 

[gixrman]

ya i was doing a sensor check off of my SAFC, the sensor #1 was moving all over when i hit the gas, and #2 stayed at .5 so prob that ones bad right???

????????? How are checking your o2's with the AFC?

 

[1bad92awd]

Its your O2 sensor, the same thing happend to me, just get a new one in there and reset the code for your computer and should be set.

 

[OTDlifer]

which O2 sensor, the front one???? and there still hasen't been a code that popped up for it, or are you saying that i just need to put a new one in, and disconnect the battery. as for the sensor check, theres an opion under setting for a sensor check. it says sensor #1 and #2. i just figured they were the O2 sensors

 

[1bad92awd]

which O2 sensor, the front one???? and there still hasen't been a code that popped up for it, or are you saying that i just need to put a new one in, and disconnect the battery.

Well when my car did it, i got a code to pop up for it, if you havent then i wouldnt worry about it. But yes do the front one, they are only about $50 so it might not even be a bad idea to replace both, but i would say try the front first if your on a budget.

 

[OTDlifer]

ok i'll do that as soon as i get back home, what about the sensor check on the SAFC, ever hear of it

 

[gixrman]

ok i'll do that as soon as i get back home, what about the sensor check on the SAFC, ever hear of it

The sensor check for the SAFC is for its sensors only. The only way you can read o2 voltage though the AFC is with the blue wire mod, but its highly recomended that you don't do it.

If your o2 is bad it will difently throw a code. The car will run like ass since the ECU goes to a back up fuel map.

Since the muffler shop installed your exhuast I would craw underneath the car and check to make sure they did'nt pinch the #2 o2's wires or cut they in some way.

 

[OTDlifer]

ok i'll check that out too, but i don't think they even touched them, just the grounding wire. which i'm giong to get the factory one and put that back on

 

[OTDlifer]

ok so i checked out the A/F gauge and its still hooked up. i ordered the front O2 housing from machV, just waiting for it to get here. if it is the O2 sensor, how come no codes have come up yet???

 

[OTDlifer]

bump