Alright hopefully someone on here will have some ideas on what the heck is going on with this car: 2003 evo 2.4L motor, stock ecu with tephra wally 450 pump, 1000cc high z injectors, speed density, etc etc.

Problem i am having is extreme lean conditions at anything over 1/4 throttle and by lean I mean off the charts lean on the aem wideband and car spits and sputters. I am running out of ideas on what to check. I tried the following:

Comp test, leak down test, boost leak test, plugs, coils, fuel pump, injectors, regulator, wiring, pump voltage, pump relays, tps sensor, Only thing I haven't tried yet is another omni 4 bar but im hoping to find one tomorrow and test it. Idle is great even cruising is smooth but as soon as I accelerate it goes lean under any load really.
Car was tuned beginning of summer and ran flawless with no issues, no changes were made to the car it randomly started running lean .
Anyone here have any ideas on what is going on or what i should be checking? i even tried adding fuel in the tune and it doesnt make any difference.
Hope soneone on here knows what is going on and whoever figures it out is getting a case of beer

 

fought this same problem on an sti for a year. i know you said you checked the fuel pump but did you monitor the fuel pressure against manifold pressure? in my scenario the customer swore on a stack of bibles that pump was new, and it was . it would even hold pressure up to 45 psi then it would leak out of the relief valve inside the tank. causing it to go lean as pressure/load increased. just a thought

 

Hey Thanks for the reply, at first I thought it was the pump too but she puts over Well over 100psi when jumped. Then I thought Maybe the aeromotive regulator was bad so I swapped it with another out of a working evo and same sh+t.

 

Perhaps the fuel pump isn't seated correctly at the o-ring int eh fuel hangar assembly... that has been know to cause the same issues you are talking about.

 

fuel filter?

anyway to monitor the pressure on the rail?

i have a in car fuel pressure gauge in my car which is really nice.

 

Car has a aem rail and aeromotive fpr with a gauge, according to the gauge it's definitely getting pressure. Had the fuel pump out three times and triple checked everything, I will swap injectors and rail tomorrow with my personal evo and if that doesn't fix it then I have no clue.

 

I have what sounds like the same issue, every figure anything out? pm me
thanks