Ok so i finally got 42lb injectors and a pro m 80mm maf,did have 30lbers with FMU and 255 pump, having some issues, If im driving along in 5th gear or anygear and leave offf the throttle for a while the car sputters and then clears out wen i rev it, also if it shuts off I have to floor it to restart it, I have the fuel psi set at 42, and I left the FMU on because i dont have a recalibrated disc for it ,i did remove it and boosted the fuel press to 60 and it didnt run nearly as strong and it was leaning out so i didnt get on it too much It feels like i gained hp at higher rpm tho leaving the fmu and 42psi, any help with the fuel pressure? and I keep reading to remove the FMU but im scared to lean it out and it doesnt run as good. what would be best, Do I just need a tune or what?
Need help
- Thread starter saleen880
- Start date
You're flooding it with too much fp. Those 42's can flow tons of fuel. You need to take it to a dyno and have it tuned. No way around this. Can't run larger injectors untuned! You will have major drivability issues and can destroy the engine. Rich is as bad as lean.
My base fp is at 26psi at idle. Start it up and back it down to there and see how it runs. Bigger injectors need less pressure than smaller ones.
My base timing is set on 12*. Maybe this will help until you get it tuned.
You don't need the FMU anymore either. If it is leaning out with the 42's and the 255 intank its unlikely unless you are making over 500 rwhp. Looking at your impressive engine combo you probably are making some serious power. (Or will once tuned) Then you will need an inline fuel pump as well. Let your tuner decide if you need the fmu or not and it will need to be calibrated for the 42's.
Good Luck
My base fp is at 26psi at idle. Start it up and back it down to there and see how it runs. Bigger injectors need less pressure than smaller ones.
My base timing is set on 12*. Maybe this will help until you get it tuned.
You don't need the FMU anymore either. If it is leaning out with the 42's and the 255 intank its unlikely unless you are making over 500 rwhp. Looking at your impressive engine combo you probably are making some serious power. (Or will once tuned) Then you will need an inline fuel pump as well. Let your tuner decide if you need the fmu or not and it will need to be calibrated for the 42's.
Good Luck
yeah I think im going to get the fmu recalibrated for now and lower the fuel pressure...i cant get it any lower than about 42psi, i must need a different regulator,its the third one and the same problem,I had the car dynod about 2 years ago with 30lb injectors and less done to the car and it made 480rwhp and the guy told me my injectors are 100% maxed, he also told me it would blow up if he ran it the way i brought it to him, funny thing is I drove it like that with no probs at all, so when he tuned my chip and when i picked the car up and drove it, it ran like **** with only 420 hp and i told him about it so i left it another day and he put the fmu back on the car, that he took off without telling me,and the car made the 480 hp so i go and pick it up and it ran ok but not as good as it did with no tune so when i got home, out with the chip and back to the stock tune....i wasted about 500 bucks on nothing I was and still am pissed.
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