pay no attention to that man behind the curtain.:muahaha:
ya my car makes that noise to but not constantly i have no clue what it is but i suspect the bov is dyeing when it breaks im sure ill figure it out till then like chuck norris... i wait

 

The same thing happend to my car. I was running stock turbos on stock boost and was getting a POP noise from under my hood everytime I would hit at least 1lb of boost.

I changed my sparkplugs to NGK and gapped them to .38 and replaced the wires.
I then also checked my intercooler pipes and pipes going to the turbo. I noticed a crack on the rubber that hooked up to my rear turbo. Since I was already working on the car I decided to use eletrical tape just to close the crack up... it pretty much took the whole role make sure it was sealed up nice.

After doing all that I pretty much never had any problems. Im not really sure what caused the problems but it either was the spark plugs, wires, or my rubber hose being cracked and letting boost pressure to come out.

I also had a 84 200sx that made a POP noise under boost because of a hole in the intake. So just check your hoses for cracks.

 

First thing to to do is verify that you're not overboosting. Check for vacuum and boost leaks and tighten all clamps tight after you verify that you have none. You sure you're not running lean and backfiring?

 

I really have no clue what it could be I guess my next step would be to check for leaks. To give a little history of the car:

Bought it in July. Early October was the first time I heard the pop noise when I was driving home with a chick trying to show off coming onto the interstate. I had no clue at the time what it could of been. Around 1-2 months later my check engine light came on. Firestone read the code and said my mass airflow sensor had caused the light to come on. I replaced the sensor and a week later the engine light came back on. I took it to a mechanic and his device said the 6th cylinder was misfiring.

This is when I started researching to see if my plugs/wires could cause the noise and read about spark blowout. I went ahead and just replaced all my wires and plugs last weekend and after I took the car for a spin sure enough it still would pop.

The reason I think it's boost related is because once on the highway I had resumed cruise control and my boost increased but my RPMs stayed the same and I got two pops with about 1.5 seconds inbetween.

I don't think im overboosting my title should probably read building boost.

I left the gap on the plugs @ factory settings. I guess its possible it could be the gap but would you need to gap iridium plugs down even when the car is all stock?

 

Yea I would gap the plugs lower. But I would check the Bubble that connects to the two turbos after the mass air flow sensor. On my car I had a small tear(crack) on the rubber part that connected to the back turbo. (the part that sucks in the air)

 

Stock y-pipe leaking? Check for air leaks in your engine bay, especially where the y-pipe meets the throttle body.

 

Is a stuck wategate possible ?

 

I would say you should do an intake pressure test for sure. There's a thread somewhere about how to make your own pressure tester.

 

you have a air leak after your mas air flow and before ur turbos. it is causing you engine to lean out as extra air is going into your engine without being measured, which would cause the airflow meter to throw the code. the popping is a back fire coming back into the intake. fix the leak asap as continous leaning will destroy an engine. most likely to be flexible rubber pipes between centre "bubble" and turbos.

 

I made the pressure testing pipe from this link

RDR Intake Pressure Tester for a Turbo 3000GT or Stealth

I'm going to try it tonight. Is there anything I need to know about doing it or do i simply just hook it up, slowly pressurize, and listen for leaks?

Also I got that torque application for my android phone and a bluetooth adapter for the ECU. My fuel/tim ratio is running at +16% on both bank 2 sensors and its around 0 bank 1. So it sounds like its adding fuel to compensate for the excess air if I'm understanding that right. Also my 6th cylinder misfire check engine light just came back on for the 2nd time. Don't air leaks usually cause random misfires? I've had both my misfire lights come from the 6th cylinder.

 

A spray bottle with some soapy water will aid in finding leaks in the intake.

 

Just got done with the pressure test a little while ago. Couldn't find any leaks except from my bov. The bov seemed to leak no matter how much air was being put in it came right out the bov. Would a leaking BOV cause the performance issues and misfires im experiencing?

I've also had two 6th cylinder misfires this week and I've had that cylinder misfire before I changed my plugs and wires as well.

I think I'll buy new coils and a new bov.

 

Yes absolutely

 

I replace the coils first and nothing changed. After I reset the codes a week later 6th cylinder misfire and fuel trim malfunction bank 2 came on.

Threw in an evo viii bov and this drastically improved performance. However the POP noise is still occurring, but it takes more engine load or boost to pop. It used to pop with moderate acceleration and that went away. However, if I punch the gas it will still pop.

I did pressure test on my intake and I could hear a tiny hiss coming from around the throttle body area, or almost behind it if there anything there that could leak. I just replaced the gasket for that a few months ago. This is a real tiny hiss do you think could cause the poping? Not sure if its backfiring or what.



Edit 4/5: Fuel trim malfunction bank 2 engine light came back on.