I have an 02 mustang gt with basic bolt ons, svt focus fuel pump and a 100 shot nx single nozzle wet kit. I got a dyno tune for the 100 shot the other day and the very first pull went completly lean that he had to back off. We checked connections and solenoids too make sure they were clicking and everything seemed to be functioning ok. So I told him to do another pull and see what happens (bottle 1000psi for both runs). This time it was slightly lean in the begining and then in the middle it got worse (mid 13s) which probably lasted a 1000 rpm or more and then in the end of the pull it started to have good air/fuel ratio (mid to high 11s). I have a fuel pressure safety switch hooked up and it didnt cut of the nitrous so the fuel pressure should be good. The tuner thinks that the fuel does not have enough time for it to react quick enough. He recommended a nx fuel accumulator but it turns out that it doesnt work for my mustang, I think he said only for the ls1. He checked with nx. Anybody know how to fix this problem? Im supposed to take it back to him but dont want to spend a ton of money. I dont want to make an independent fuel system for the nitrous (too much money). Any other ideas?

 

Sounds like you need a tuner who actully knows how to tune for nitrous. A good tuner can compensate for when the nitrous first hits and goes lean, and then fix the rest of the a/f ratio out after that.

On another note. Since are cars have a returnless fuel system it does create a nasty lean spike at first, but like i said it can be corrected.