68 CHEVELLE IN CALI

I Just Installed A 6.0/4l60e In My 68 Chevelle
When The Car Is Decelerating It Seems To Be Popping Out The Exhaust.
What Is The Next Step That I Would Try To Figure Out The Problem
I Seem To Have Approx 48 Lbs Fuel Pressure.
If I Was To Buy One Of The Aftermatket Systems Would It Be Able To Tell Me If There Was Something Wrong With My Fuel Curve?

mullenh

iTrader: (1)

not enough info. do you have a fuel pressure regulator?

68 CHEVELLE IN CALI

I Have The Whole Stock 6.0l Set Up DUAL FLOWMASTERS OUT THE BACK

mullenh

iTrader: (1)

?? the exhast isn't the problem it is the extra fuel dump into the exhaust that backfires or is it a backfire?

67RSCamaroVette

iTrader: (63)

mine pops loudly on decel, it's more of a roaring noise with the occasional pop, I think its normal when you've got an unrestriced large diameter exhaust.

6L.IROC-Z

iTrader: (6)

Pull a spark plug and inspect it, that will most likely indicate that that it is a air/fuel ratio problem.With the limited info its sounds like the motor is running lean (to much air) the exhaust is super hot because of the lean condition and when you deccel. all the unburned fuel is ignited when it enters the exhaust causing the backfire. if the engine was running rich the exhaust wouldnt be hot enough to ignite the unburned full. if you pull a spark plug and it is really white or tan its lean. I would check for a vacum leak around the intake and all its connections. just my 2 cents worth.

tooblue

Yahh I noticed a similar condition when I first completed my conversion. It is very minimal now after double checking for exhaust leaks? I also put in a crossover pipe and that really calmed the "poping" sounds. Hope that helps.. Roger

SICMARO

i know ls1/ls6 need 58-60lbs dont know the truck info. might need more fuel.

Project GatTagO

iTrader: (7)

You need to raise your fuel pressure to 58psi.

Andrew

mullenh

iTrader: (1)

agreed.. but Idon't think that will solve his problem

Project GatTagO

iTrader: (7)

It may. Sometimes if the mixture is very lean it will backfire through the exhaust.

Andrew