My car is a 93 Lexus SC300 with a non-vvti 2jzgte. Walbro 255 in tank with full -6an lines ran to the afpr and -6an as the return line to the tank. Since Ive had the car its been running perfect on part throttle. Idles at 850 rpm but idles rich at 11-11.5 afr. With the car off and fuel pump on, the static pressure is right at 42 psi, once I start the car is goes down to about 35-38. When I hit the throttle it shoots back to 42psi. 8psi on A Borg Warner S366, Tial 40mm waste gate, big fmic, 550cc injectors, JDM TT ECU, with a safc.

The problem is, under WOT the car breaks up and afr shoot up to about 14 and it'll start to breakup and miss fire and go into the 16's. If I do 75% throttle, the afr are solid at 11-11.5. I have no idea what to look at next, doesn't matter if Im at 0%+ or 30%+ on fuel, it always goes lean.

 

Have you done the 12V fuel pump mod?

 

Yes. Power is pulled straight from the battery then ran through a fuse/relay. Pump goes full 12+ volts when running.

 

i would double check the FPR and trouble shoot that first. then proceed with the tune.