Smoke_Ford

I just recently did heads/cam, see sig, and the car has yet to be tuned. I did the heads/cam last fall, and the motor spun a bearing. That was the last time I put gas in the car. Since then, I have swapped the motor, and used the same heads/cam. Under 2000 RPMs, with light to moderate throttle, it will backfire once or twice. Any higher, the car is fine. Under WOT, it sounds amazing and pulls like a ****. What could be the problem? I thought bad gas, clogged injectors. My buddy said it could be a bent valve, although I don't thik so because the heads have a total of 80 miles on them since they were last built. Any ideas? My buddy aslo suggested that the O2s are bad. Any input would be glorious.

Mike K.

I remember when i had my Loudmouth I had the occasional backfire, maybe your running a little rich? Do you have tuning yet?

1RawTA

iTrader: (1)

i get backfires when my car is cold, i also think my car is running a little rich too, anyone got any ideas waht it can be?

Smoke_Ford

No, it is not tuned, and yes, I am running really rich.

Pro Stock John

iTrader: (34)

Easy way to test it is to borrow a MAF-T and lean out the base setting a little and see if it still does it.

Smoke_Ford

What is a MAF-T? Keep in mind, I work at a dealership. I should have this problem solved on Sat. Ever since I burned the gas out, put fresh gas in, and put in some HEET, it has been running better.

Pro Stock John

iTrader: (34)

It's an aftermarket device.

You know, I'd make sure that you don't have a loose plug or wire, you might be loading up in one cylinder. After you run thru a tank of gas if it's still doing that I would try to lean it out if it's rich or check some stuff.

Cal

iTrader: (1)

The gas has been sitting in your car for a year, so of course it is bad. If it backfires as you let off the pedal, this is normal. You just don't normally hear it unless you have a loud exhaust.

soundengineer

iTrader: (16)

backfire happen at partial throttle only????

O2's definately...
at WOT it ignores the O2's...henceforth...no backfires at WOT...

Definately O2's

ZDOG

iTrader: (13)

are you talking about when its a cold start up and it "pop pop pops" on the decel from a rev or does it do it all the time? i got an 02 z with less than 8000 miles with no engine mods just a loud mouth and it pops and snaps like a **** when cold. or are you backfiring through the intake?

Smoke_Ford

No, it has gotten MUCH better since I have burned out the **** gas. I am still thinking O2s, but the car drives VERY well at this point. I have not heard a backfire yet today.