Originally Posted by hollywood_X

Bringing this back from the dead....

A friend on mine is having a similar issue and just checking back here to see if you found a solution. Now he is getting lean brake up at higher boost levels mostly but there were a couple times we got it at 18-20psi it just wasn't as noticeable. On his car he has an Evo 8 running what we think is an Evo 9 turbo but he isn't sure. We are also running E85 and 1250cc injectors with a 255 in tank.

Now what happens is at peak torque when we get full boost 24-28psi the car will lean out and lean POP, this happens no matter what we enter into the fueling for that area. Now if we add fuel in any other part of the map we don't have an issue getting the fuel to change. At first I was thinking it may be a boost leak or the fact the FPR line was running through the stock solenoid but neither of those seem to be an issue.

Now I am thinking he may not be getting the correct fuel pressure due to a bad FPR or a leak at the pump maybe.

Thoughts?

Originally Posted by tscompusa

a misfire will be seen on a wideband gauge as a lean condition. if the fpr is bad it would not go 1:1 with fuel pressure and boost as your boost rises. if its not leaning out the higher rpm you go, its not the fpr. (it'll lean out higher in the rpm due to higher airflow and the need for more fueling at those high airflow conditions).

try replacing the plugs and closing the gap up much tighter and retrying. if it continues, then test the coils on the ignition.. if that checks out, then check the fuel pump & wiring.