Ok so i got my car back from the dealership,( was at the dealer for 2 months getting the shepp tranny so it was still cool before i took it to the dealer) and was driving my car and did a WOT pull, it was the middle of the day about 105 out side, and my car was running like crap hitting 15.4 A/F ratio. So i was like WTF and its been like this for a few days. So tonight coming for the gym i decided to do a lil testing, it was about 10pm about 84 degrees and did 3 WOT pulls and each one was perfect hitting 11.9 to 12.2 A/F ratio. So what is going on how is my car running so crappy because of the temp. I have other buddies that live out here and they said there cars run fine day or night. Any ideas?

 

Make sure the vacuum hose running from your intake manifold to FPR is on securely (zip-tie it to be sure) and switch out the stock black fuel pump relay for the new/revised blue one. These are two very common failure points, even on stock X's.

 

The hotter the air, the less dense it is. Still though, the air metering and temp sensors should allow the ECU to compensate for that. Does your tune (hardware, software) have the ability to adjust depending on ambient and extreme IATs? Any knock present?