Predator may be causing misfires on truck

[06MonteSS]

when's the last time you cleaned your MAF sensor?? get a can of CRC Mass Airflow Sensor cleaner and cliean it up good...

[tarpon4me]

I cleaned it about a week or so ago. I didnt' use CRC, but I used automotive electronic cleaner. Been getting that P1133 code since I took the crap custom tune out of my truck. I'm pretty sure that is the cause of that particular code considering the long tubes. RPMonline did a crap tune from the go. (not the predators fault) I have better throttle response and it runs smoother all the way around with the canned 87 octane tune. Go figure.....

But, the tune is not causing the misfires, i've ruled that out. I'm worried now that I may have internal motor damage of some sort. I've read that damaged heads can cause issues like this.

[mikel]

weak valve springs will cause random misfires as well....

[tarpon4me]

weak valve springs will cause random misfires as well....

I thought you might say that.

[mikel]

I dealt with that for months after buying some junk springs for my car...I could pop the valve cover and push the springs down by hand when they got soft like that. When they are that soft, the valve just bounces on the seat, and causes misfires...

[tarpon4me]

Mike, anyway to diagnose the valve springs with out tearing it down? It's the stock valves springs in it.

[mikel]

not to my knowledge...

It really only takes about 5 minutes to pull a valve cover on these things

[PowerPhreak05]

Crank sensor relearn maybe? Have fought Phantom misfires after a GM reflash before on a 2500hd 6.0. Wasn't really missing all that bad, but it was enough to trigger a mil and kick out the toque converter. Did a crankshaft sensor relearn procedure and it cleared up. I even put a new intake manifold and exhaust manifolds on it, thinking that i was chasing A/f based misfires. Used my snap on solus. Any good diagnostic scan tool with functional test capability should be able to do it