Hey guys. Looking for some help here. About 2 years ago I swapped an 86 TPI T/A engine and trans combo into my monte carlo ss. it ran beautifully. in the last 2 months im getting a loud popping, or backfiring around 4k rpms. I understand that it could be anything im sure, but so far ive checked and/or replaced the following-

cap/rotor
ign. coil
icm
wires
plugs
ESC module
MAF
engine wiring

Ive been doing alot of reading at chevythunder as well and that site is saying it could be the knock sensor. Could this be true? Im on my second MAF and its still throwing me a code for the MAF randomly.

 

When does it backfire? When the throttle is open or when you let off?

 

on acceleration around 4k. probably starts at about 3800 rpms

 

nj85z28,

We are having the same problem. My car will pop when I hit the n2o. runs OK without,,,,but it has a kind of surge without the laughing gas. I noticed when I rev my car in park, the car kind of .....falls on its face @ 5500rpms. Not the kind of fall on your face that's normal, it surges.

I'm wondering what your car does when you rev it in park?

Is your car popping out the exhaust? or intake? Kind of important to know. out the exhaust = fuel, intake = lean.

 

its popping in the intake and will do it in park if revved high enough. thanks

 

what kind of timing are you running with the est unplugged? If you are running anything more then 6* with the stock ecm its going to add that much more at every point in the spark advance table. I would suggest either backing down the timing or change the base setting in the computer

 

ill look into that thanks

 

I'm gonna guess your running your timing to far advanced or low octane.

 

im running 93 octane and have never touched the timing

 

this is still an issue..anyone?

 

So is it popping through the exhaust or the intake?? I have an issue with popping in the exhaust? I wonder if our issues aren't timing related. I am going to have to do some reading to determine which though. Mine might be advanced, and yours might be retarded in that it is igniting the fuel mixture while the intake valve's are open.