RB20 boosting issues

[matienZo]

Me and a few friends recently swapped in an rb20, and after a constant amount of headaches and solving multiple problems, I'm finally stumped.

Car:90 240sx coupe
Engine: rb20det
Mods: fmic, stock everything, ngk bkr7es-11 spark plugs, walbro fuel pump, open dump pipe
Problem: My car would cut out into boost, so I installed a walbro thinking it was a lackage of fuel compared to stock pump, when I did, it ran sooo rich that it would spool, but not go into boost, then sputter. So I let the car sit there while it snowed the past week, and the battery was dead so I jumped it off and it ran great, went into boost, but I can't tell how much because I don't have a gauge. But then, after about 20 minutes of driving pretty hard on it, I let it idle for about 5 mins and I looked up - it was running alittle hot so I hopped back into drive it to cool it off, and it was doing the exact same sputtering and wouldn't hold idle well. So I reset it again and it drove around just fine, but after about the same time, it went back to sputtering.

Cliffnotes: When ECU is reset, for about 15-20 minutes, it will drive/boost fine, then it will sputter in boost and not hold idle well.

Any ideas? Could it be a bad ECU? Plugs getting too hot after driving?

If you need any more info, just ask. Thanks ahead.

[Carl H]

check your fuel pressure...make sure it isnt dropping.
resetting the ecu will reset fuel trims, normally after a reset they are rich and the ecu will lean it out.
also check for codes, wouldnt hurt to check timing.

[matienZo]

I should probably buy an adjustable FPR since I'm using a Walbro, but I'm paying for school right now so I'll have to put that on hold for abit.
Other than that, I don't see any reason for it to run rich/drop pressure in boost.

I'll definitely check for codes, but do you think my ECU is fine or should I look into trying a new one?

[Carl H]

pull codes first...cheap and free.

[TheRBguy]

Even with a walbro you dont necessarily need a fuel pressure regulator without one when you drop the pedal it just crackles and pops a bit it doesnt hurt anything.

[matienZo]

For the record, I just reset my ECU and it runs great, just a little rich. Probably could USE an adjustable fpr, but not required.

[Carl H]

sounds like you did something to trigger the switch to knockmaps...might want to shoot base timing and make sure its in spec.