Allright, heres what happened. i just got nitrous for my car a while back. I just went to the dyno to see what the car would do. I mainly wanted to get a feel for the AFR because i dont have a guage right now. Long story short, we strapped it down, and ran a baseline NA, and the car was at 18:1 the WHOLE RPM band . we thought it was his sensors, so he put on some new ones, and it was the same thing. tried them out on a pickup, and they read fine. so my car is definitely reading that lean, and i dont know why. i have TSP's 233/239 cam, headers, ORY. I also have a mail order tune from them. The last time i dynoed my car it ran around 370hp without a dyno tune, which wasnt that bad. but now im running lean and cranking out a whopping 277hp. What could be the problem here? we checked the fuel pressure and it was around 58-62 psi. but the car is still extremely lean. any suggestions? has this happened to anyone else?

 

First off, fire your dyno guy! The minute he saw that A/F start going up, he should have got out of it, not finished the pull. So are you running that lean on the spray or NA? Is your nitrous a wet or dry kit? No vacuum leaks or anything? Assuming the car is in good health, if its running like that NA, then i'd say your tune is off and needs fuel. If its on the spray, then the fuel is jetted wrong if it's a wet kit, and if it's a dry kit, then the regulator jetting is wrong. Or, if your on the stock fuel pump, then it's not keeping up and starving for fuel, in which case, you'll need a HV pump.

Ken R.

 

The big question is when is it running lean, in NA form or with the spray? If it is running lean in NA form, I would look the car over for major vacuum leaks. If it is doing it on the spray, I would double check your jetting and make sure your fuel system is supplying enough fuel to meet the demands of both the motor and nitrous system.

 

According to his post, it was lean for the NA run. You stated that you verified fuel pressure was fine. Other sources would be faulty injectors, bad tune, bad but not dead MAF.