Backfiring on stock SR20DET, didn't use to..always had open BOV...help

[junk240sx]

I've already posted this in RWD SR forum but not getting enough views. :P So I am going to ask here. I have a '90 240sx with SR20DET and vented BOV. Stock fuel setup and stock MAF.

I've always had a venting BOV and never had backfiring problems until this week. Only backfires when in gear and not on the throttle. It backfires constantly until you take it out of gear. Now it only backfires in that situation. Normal driving is fine until you let off the gas and leave it in gear.

Then, today, I even lost power. Now if I step any more than 1/2 inch on the gas pedal, I lose power. I'm still building boost though. I can floor it and get full boost but no power at all. So I'm sure I'm not leaking boost but something is obviously wrong.

Can anyone help? I've replaced the spark plugs since it was a cheap easy try. But that didn't help at all. What is different about slowing down in gear without the throttle open that would cause backfiring? and why will I be pushing lots of air into the engine but not feel any power???? I'm lost...I feel like it's probably a simple thing...

[Silvia007]

I'd swap mafs. A buddy of mine here who goes by the name "SR20DET" had the same problem. He finally went with a SR20DET mafs and it still was bad. What he did was hard wire it, Ground the ground wire to the chasis, get a switched power supply to the mafs, and hard wire the signal wire to the ecu and it seems to work now. It used to be so bad, he couldn't even drive it. Backfires like hog with gas problems. We switched SOHC mafs to Z32 Mafs, etc, until we got the actual mafs. But I think it's just the wiring. Hope you find your problem.