96 Mustang Performance Issue

[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 tuner

I 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.

 

[Dark04GT]

4.10’s should be ideal for 1/4 mile on a near stock 96 GT auto. You should be in the thick of 4th gear at the end.

First thing I would do is basic maintenance and running down what the issue is that you are throwing codes. O2 codes can be non specific and represent tons of possible issues (usually not the O2 sensor). Most likely if you have an issue that is causing the non specific O2 codes then you might have an issue that is robbing your power.

 

[Neuron]

4.10’s should be ideal for 1/4 mile on a near stock 96 GT auto. You should be in the thick of 4th gear at the end.

First thing I would do is basic maintenance and running down what the issue is that you are throwing codes. O2 codes can be non specific and represent tons of possible issues (usually not the O2 sensor). Most likely if you have an issue that is causing the non specific O2 codes then you might have an issue that is robbing your power.

You meant 3 rd gear right?