sschoeffler

iTrader: (24)

Ok guys I have a 408 (4" forged stroker crank and 4.030 JE boost pistons) and when I put it together at first I put the stock LS1 camshaft in it and it worked fine with no backfiring. Now I have put a cam in with 222/238 duration and around .600 lift on the lobes and the damn thing backfires when cold until it warms up then idles fine. It hasnt been tuned yet, I've got Comp Cams 7.4 hardened pushrods and it doesnt sound like a sewing machine when ideling. I havnt installed my injectors until it gets to the tuner. What could the problem be? Keep in mind it stops backfiring after it warms up.

smok'nZ

iTrader: (160)

congrats on getting it running, who is gonna tune it?

98PurpleT/A

iTrader: (16)

you still have AIR system??

99T/ATIME

iTrader: (3)

It's probably in the tune....I'd have it tuned before doing anything else.

sschoeffler

iTrader: (24)

I'm going to have a buddy in Broken Arrow give me a tune that will get me to Oklahoma City so Glen can tune it. I've already bought the tunercats credits from Justin to get it tuned. I'm hoping Glen can give me an SD tune so I dont have to use the MAF.

That AIR system was one of the first things I yanked off when I bought the car 3 years ago. Its been tuned out and deleted completely.

sschoeffler

iTrader: (24)

Another thing I have noticed is that I am having oil pool up into the bottom of my intake manifold and I've got a Rev Extreme catch can hooked up on it. I've probably put 800 miles on it with the LS1 camshaft and about 1 hour of run and idle time on the new camshaft but 0 drive time.

51/50 GTO

Lean conditions can cause backfiring through the intake. If its a exhaust backfire it could be a miss fire condition of some sort. It probably just needs the tune.

sschoeffler

iTrader: (24)

Come to think of it my check engine light blinks all the time while running and the code is cylinder misfire. Camshaft was lined up dot to dot and I'm running a Cloyes Double Adjustable timing chain...Do you think the timing chain loosened up enough to throw yhe timing off? I know that the motor is sluggish as hell until it warms up, afterwards with the aluminum flywheel it will rev up quick as hell, before its warm it revs real slow.

99T/ATIME

iTrader: (3)

I'm sure you have already, but have you checked the plugs and wires??

sschoeffler

iTrader: (24)

Its running rich but thats to be expected without tuning. None of the plugs are showing lean conditions.