going lean at wot


Active Member
so i fixed a couple of vaccum leaks put my new powerstroke ic on. put in a new 340m pump, racetronics hot wire harness, fuel filter, and fuel pressure regulater and also put in a razor alky kit and and tt chip. made a couple wot passes to test everything out and noticed the my o2 reading on the scanmaster were between 650-700. Fp is at about 45psi line off. and im running about 24psi boost. not sure were too look if almost all fuel parts are knew. can someone help
Make sure you're seeing 69 pounds of fuel pressure at WOT (45 line off + 24 pounds of boost).
It should rise 1:1 with boost, if it doesn't you most likely have a bad fuel pressure regulator.

Also confirm WOT voltage is where it should be, low voltage to the pump can cause low FP as well.

If you have access to a wide band confirm the car is lean, I don't full trust 02 readings as accurate air fuel data.
Are you using an OEM MAF sensor? If your MAF sensor isn't reading high enough then your chip will never command the power enrichment mode and you'll be sending all that air into the motor with not enough fuel.
did you get your tt chip before upgrades or after and if so did you give him your upgrades. you may try to add 5 % fuel in all gears wot. with that intercooler you may need more fuel
yes im using a OEM maf
and yes i had the tt chip made after my upgrades

havent got a chance to check fuel pressure at wot because its been raining but as soon as it clears up ill make sure i check that out
how do i confirm voltage and what should the voltage be at?

Measure the power going to the pump under the rear bumper, at the hotwire relay, with the engine running. You can 1) put 24 psi of air on the regulator or 2) dial up the base fp to 69 psi (line off). You should get with 0.5 volts of what you measure at the back of alternator.

But the bottom line is what is your fuel pressure at WOT, that is what you are really after. Put a gauge on that you can read from the cockpit.
seem to be a voltage probleme how do i fix it?...i got a translator and a lt1 maf and check fp at wot everything is ok but voltage seems to be low how do i fix it?