natifam

I’m having some issues with my car that I can’t wrap my head around. I was hoping someone here has an idea or two. Here are the basics of my car. I drive it back and forth to the track and that’s it.96’ auto, pretty much stock except 4.10 gear and cool air intake and I’m using the SCT X4 tunerI had the 4.10 put in a few weeks and the results have been very disappointing. I actually slowed down at the track by 0.20. My 60-foot picked up a tad but I’m losing everything from there on and losing about 2 mph through the ¼. I’m not sure where my issue is at. I’m getting a few error codes such as the car is running to lean and some O2 sensor issues. I know the O2 is good because I just replaced them a few months back. I set the tune back to stock and then ran it again and had the same results. I’m at a loss at how I have no improvement with the addition to the 4.10. Things I know is not an issue. Yes, I’m sure it’s a 4.10 gear. No traction issue using Nitto tires and they hook no problem.

Derf00

Were the Cold Air Intake and gears installed at the same time? If they were, try putting back your OEM air intake and see if the problem goes away. Running lean means you don't have enough fuel being fed into the cylinders to run at the optimum AFR.

You could also check for leaks in and around the intake hose.