curbcheck

so, i tried to start my car and it cranked a few times and sounded like it was going to catch so i let go of the key, it almost started but it stalled and then i heard a very loud backfire through the intake. I popped the hood and noticed that the backfire blew the cap off the front of the intake and dented my hood. Im going to upgrade to an ls6 intake and replace the hood with a cf hood but i dont want it to happen again. what would cause a backfire like that? its an ls1 with an ls1 intake and a mild cam. it runs and drives just fine. could it be in the tune, an intake leak, leaking injectors, or maybe a bad crank sensor? any input would help, thanks

rigid

iTrader: (5)

You got pretty lucky that egr plug popped out. Mine took out the whole *** end of the intake. All the little plastic pieces got sucked in and took out the engine. The engine stayed running and shot to full rpm, on a curved on ramp to the highway. It put me in a ditch. I rebuilt the engine and it hasn't happened since.

jimmyg

Check that ecm has 12v during crank mine backfired while starting too until I fig out. Take a test light to ecm switched ignition wire while cranking

KiwiStarChief

My 5.3 backfires if I turn the key and start straight away, rather than turn the key and wait for a few seconds before firing it. I presume that the fuel pressure is not high enough initially, and that it builds up after a few seconds?

curbcheck

Damn rigid that sucks. Good thing no one wasn't standing over the motor when mine blew out. Thanks jimmyg I'll check into that

chuckd71

iTrader: (23)

Damn, I've never seen that before. You and rigid got lucky in the long run, things could've gone way worse. Makes you sort of count your blessings.
Might get someone to at least look over the tune before you change hoods, that probably would've gone straight through a cf one. My backfires turned out to be bent valves, but I'd think that's unlikely in this case.