Update= The truck is at a repair shop. I got a call today from them, they told me I didnt have enough exhaust back pressure and that was causing the intake pop. This makes no sense to me, since I had the new cat and exhaust installed and has been in use for the last 8 months. Anyone else have any input. Im going to pick up the truck tomorrow and go thru the wiring like army_greywolf suggested.

 

For the record I have no cat, original Y pipe, shorty headers off ebay and a side exit dual exhaust in front of the rear tire...so I highly doubt that's the issue. If they'd like an example I'd be happy to post a picture for reference tomorrow.

 

I figured they were full of sheet. Its hard to find a trustworthy mechanic. I guess im going to have to figure this out by myself. For the record I also have shorty headers, hallowed cat, flowmaster 40 series muffler and 2 1/2 rear exit pipes.

 

im having this same issue. again, motor went in about 10 months ago, backfiring through the intake started about 2 months ago.

let me know what you find. ive been chasing this thing for awhile now. one thing to check is your o2 sensors. mine isnt doing it as much as it was, now that both sensors are brand new.

are you getting any codes? if so, list em here!

 

No codes. I only have 1 o2 sensor and its been changed 2x now. I have a few things to check. I will keep u posted redneck.

 

On an older motor, I would begin to suspect fuel sync was off. That shouldn't be an issue on a new motor..... not if it ran right for quite some time.

 

Mine only does it at low throttle more than half throttle it runs like a raped ape.

I'm going to be pulling the engine harness on my next day off (monday). I'm hoping its something simple...

 

I would like to know what your injector driver voltage is...but you can't get that without a drb3 or a scope that can see the spike. Did both of you by chance reuse old injectors? If they aren't spraying proper pattern they will just squirt the valves and guess what problems that will have...

I still think your issue is going to be grounds.

 

Stock injectors are pencil beam in any event. The spray at the back of the valve just before/while it's opening, and the hot valve is supposed to vaporize the fuel.

 

Yea...still low voltage and they'd open late...puking fuel and running lean, which the pcm would compensate for by increasing pulsewidth width meaning they'd still be injecting after the valve closes...and you can see my train of thought there. Anyways...the likeliest thing is still electrical or (And I hope not...) timing chain/distributor. I thought about that, the distro gear may be chewed up, at least take the cap off to check play.