GenV Tuning Question

[bmac]

Guys, I'm running a series 3/GenV swap on my 2002. With an AEM dryflow air filter upgrade. I've been having problems with it running rich and fouling plugs. Do I need a MAF table tune for this? Seems like a lot of people have done this swap without getting a tune.

I did find a vacuum leak around the IAC body and replaced it. But when I drove it to drop off at the shop on Sunday the LTFT where running about -14 to -20. Seems like it's still pulling fuel back. Just wondering if the increased air from the GenV is causing the rich condition?

This is my first SC engine and I don't understand all the workings like the SC bypass Solenoid valve. This thing sounds like it's opening and closing during idle. At least when I had the vacuum leak. I'm assuming that it lets outside air in since it has that filter on the end of it?

I have ordered a Jet MAF sensor for the car and currently waiting for it to arrive. Hoping this would help with the increased air flow from the AEM filter.

[95naSTA]

How old is your O2 sensor?

What are your LTFTs during mid-throttle acceleration?

Not sure if the Jet MAF is designed for performance or something but I would get OE equivalent.

[bmac]

O2 Sensor is only about 2 years old and around 55K

I would have to double check but I would say LTFTs is around -18 or -20 during mid-throttle acceleration.

Just thru a P0172: System too Rich (Bank 1) fault yesterday morning.

I've got the new Jet MAF. New NGK Ruthenium plugs and and new GM Upstream O2 sensor to put on. Already have new plug wires and new GM downstream sensor. I was thinking with a 177k that maybe I should replace the fuel injectors also.

Any other thoughts.

[95naSTA]

It does sounds like you're running fat. It could be a leaky injector and/or fuel pressure regulator.

[bmac]

I thought maybe the fuel pressure regulator myself. I'm not having trouble starting and I haven't been able to get it to leak when I pull the vacuum hose from it.

Well after installation of the new MAF, Plugs and O2 sensor this is where I'm at!

I did a test this weekend looking for leaks using propane and didn't find any. LTFT's are still around -22 when idling. When I WOT it they drop to around -3 but quickly bounce back to around -22. Only thing I haven't checked and replaced is the injectors. I did do a fuel pressure test on them a little while back because I thought maybe I had one leaking or low pressure and they seem to hold pressure after I shut the engine off. I think running pressure was around 42. I guess I can check it again.

This thing has me

I'll keep plugging away at it....surely I will eventually figure it out.....

[bmac]

Ok, I did have a leaking fuel regulator. I've replaced it and still have around -22 LTFT's I bought a spark plug fouler drilled it out and put the upstream O2 sensor in it to extend it and see if the numbers change. Voltage looks correct, bouncing around from .2 to about .9 volts and anywhere between, but the LTFT's are still almost setting at -22 all the time they will change some but not much. I've replaced the MAF, IAC, MAP, Upstream O2 new plugs, new wires and the coolant temp sensor was replaced last fall and it looks like it's working correctly down stream O2 sensor was replaced earlier this year, but I'm not sure it's working correctly, It's showing .05V not around .5V. I didn't think the downstream O2 had much to do with fuel trims. I thought it just monitored the efficiency of the CAT.

Scheduled to go to the shop on Monday. Just wondering if anyone can give me an idea of where to go now. The LTFT's not changing after extending the upstream O2 sensor really has me puzzled. I would have expected some kind of change in the readings for better or worse. Any thoughts?

[95naSTA]

Have you reset the pcm to get your LTFTs back to zero after you fixed the FPR? LTFTs will take some time to change and starting with reset fuel trims will speed up the process. I've never owned an OBD2 3800 so I'm not sure if unplugging the battery will reset the trims or what.

I would not run a defouler on the upstream exhaust manifold O2 under any circumstance. The downstream does nothing for fueling.

Have you pulled the fuel rail up with injectors attached and 10 sec primed (key on position) to see if any of the injectors are leaking?

[bmac]

The defouler was just to see if I could see any change to the upstream o2 sensor readings, and verify that it was working correctly.

It has since come back from the shop and they said everything looked good and was with in spec. It might be running a little on the rich side but not much. It seems to be running and idling smoother than it ever has, but it thru a P0172 on the second drive after getting it back from the shop on Tuesday. I talked with them and they did not and can't reset the PCM. I think you have to have a tech2 scanner or equivalent to reset the PCM not sure about that. The mechanic told me that the only thing he would change is the upstream o2 sensor. He used to be a GM mechanic and at one point years ago they had problems with some of the 3800's but especially the quad4 engines if they used o2 sensors that didn't have the fluted openings. So if he was going to change anything it would be just to put a Bosh fluted upstream o2 sensor on instead of the Delphi with holes.

Have not pulled the fuel rail up. I don't thing my injectors are leaking, but I really wasn't sure how to accurately test that. I've read that you just pressurize the system and see if it leaks down quickly and I did that and didn't see any issues of concern.

I will keep plugging away at it and hopefully at this point it is just a matter of the PCM just getting reset or relearning. If I have time I might try pulling the injector rail and priming it like 95naSTA suggested.