back-firing

[derrick]

hi

couple of weeks ago i was doing some work on my car 85 grand national replaced some engine parts and a tune up after i finished everything. told the car for a drive and at low rpm the car back-fires thru the exhaust not load but i can hear it when driving. i did pull the egr stuff out. could i have i injectors wiring mixed up the did pull the top half of the motor off.

 

[Jerryl]

What scantool do you have?

 

[derrick]

dont have one

 

[Jerryl]

I am going to get slammed for this but . . . . truth is truth.

A scan tool is not really needed, “IF” you have great knowledge of these cars, and GREAT diagnostic and analytical skills.
For most of us (99%), that is not the case and a scan tool on these cars is vital and saves a LOT of time!
They are a LOT cheaper than head gasket replacement and engine rebuilding costs.

If the car is running OK otherwise and you are at stock boost levels (8-10), I would not worry too much.

If you run a stock car at stock boost levels, probably can get away with not having one.
If you try to push it like most of us, you are going to need a scan tool, period.

If you had a recording scan tool we could get you some accurate opinions.
From the sound of it I would guess;
Weak Ignition system
Bad plugs /wires
Bad O2 sensor
Voltage / Ground issues

 

[grnadnasty84]

I had this same problem for a long time and couldn't figure it out. I replaced the maf with a stock unit and it didn't fix it. I then replaced the maf with the ls1 maf and translator and the problem was gone. Don't know if that'll fix yours but that's what worked for me. Good luck

 

[derrick]

for the most part is it stock except for exhaust. it has brand new plugs,plugs wires and o2 sensor.