Well, I WAS going to try to sell this car but not with problems. This is a '90 240sx with SR20DET motor. As you most know, nissans have MAF sensors that monitor amount of intake air to determine a/f mixture.
People say if you have a vented BOV, you will get backfire between shifts. I do occasionally get the backfire between shifts which is ok.

BUT recently, (last week), it started to backfire like constantly only if you let off the gas and keep it in gear. It goes "pop pop pop pop pop" until you take it out of gear or step on the gas. First easy thing to replace was spark plugs for $10 so I did it without any results.

Now the problem is worse to where if I step any more than 1/2" on the throttle pedal, i lose all power even though turbo keeps spooling to full boost. So I'm not leaking boost anywhere but it's definately not giving me anymore power. I have to barely touch the gas pedal to get the car to accelerate.

I'm starting to think maybe i have a bad MAF but am stumped as to why it only backfires when in gear and throttle closed. Any help would be appreciated!

I shoudl also mention that I checked timing. It's right on. (I even retarded the timing to 0 and it still backfires the same).

 

help me...even 'ideas' would be nice. Some people have mentioned to check for exhaust leaks. Could this be the case and what is the easiest way to check for exhaust leaks?

 

What is your fuel press and are you runing an aftermarket FPR?
What do you have your plugs gapped at? What are your EGT's? What are you using to go from the filter to the turbo? have you checked for leaks there yet?
Are you running a cat?