Hey guys. I previously dynoed at 323 rwhp running a little lean (13 if I remember correctly). Then I recently installed some FLP Long tube headers, and I dynoed today. I dynoed at 320rwhp, and VERY lean (15). Now, I AM missing a bolt in the drivers side air tube, and I will get a new bolt tomorrow. So I am sure there is an air leak there. Would that cause me to lose power, and run so lean? One recommendation the dyno shop had was that the Granatelli MAF might be messing something up, but we're not sure. Wasn't too much of a problem before. Overall, car runs fine. Can't really feel anything wrong. PLEASE HELP!!!!!!! I am going back on Thursday, and have to pay another $120. I can't afford to keep paying that until I figure out what is wrong. Is it possible for a loose air tube to cause this much of a problem? Thanks.

 

that sucks man. Aren't you supposed to gain 15 RWHP from the long tubes alone! Check for error codes and if all is well. Check the fuel system...pressure, filter, squirters. My buddy has a 406 TPI that was registering lean on all cylinders. Turns out , he installed stock injectors when he was told they 30 lbs SVO's. Once the correct injectors went in, all was good.

Goodluck

 

So your saying I should change my fuel injectors? Everything was running fine before the headers install. The guys at the dyno shop think it is because of the missing bolt. I am going to buy that bolt today. We'll see what happens.

 

I don't know the details of the LS1 exhaust configuration, but if you are saying that the AIR piping is not connected solidly to the header, you could definitely be having problems. When there is an opening in the exhaust, before the O2 sensor, the exhaust gasses passing by the opening pull (educt) fresh air into the exhaust. The O2 sensors see that and record a "false lean" and richen the mixture. The excess air would also show up on the wide-band O2 analyzer the dyno shop uses.

You say your first pass was "lean" at 13:1..... that sounds just about right to me, unless there is something unique about the LS1. Most engines seem to make peak HP/torque in the 12.8-13.2:1 range. Some fuel injected engines will tolerate an even leaner mixture.

If you say 15:1 with the air leak, and that makes sense. The engine may not be running that lean... it may just be the wide-band seeing the air inducted through the leaky AIR connection. It would depend to some extent how many miles of driving you have on the engine since the FLP install. In theory, the leak should have been "fooling" the PCM into thinking it was running lean, and should have bumped the long term fuel corrections up to the point where it should be dumping in unneeded fuel and causing it to run rich. If you drove it at high loads for a significant period of time, I'd expect it to be running too rich, and for the exhaust to "seem" correct, with the leaking air compensating for the overly rich mixture.

Fix the leak.... it can only be hurting.