Backfire problems on my 1994 Mustang 5.0

[mustang1994]

This is what I did. I put 24lbs injectors in it. And this is the work I done to try to fix it. I put new plugs, new 9mm wires, new coil, new MSD cap and rotor, 2 new O2 sensors, and a 80mm MAF calibrated for 24lbs, put fuel injector cleaner, put the timing down to 12*. And it STILL backfires on normal driving.

 

[toyman]

This is what I did. I put 24lbs injectors in it. And this is the work I done to try to fix it. I put new plugs, new 9mm wires, new coil, new MSD cap and rotor, 2 new O2 sensors, and a 80mm MAF calibrated for 24lbs, put fuel injector cleaner, put the timing down to 12*. And it STILL backfires on normal driving.

And how does the PCM know you've changed injector anf MAF sizes? You may need a tune to resolve this.

 

[desertcox05]

double ck you firing order you could have mixed 1 or 2 up

 

[humphrey111]

i just changed intakes and injectors and all that too. I had a horrible backfire and it ran like poo. My problem was the vacuum lines under the intake, replaced all those hoses and PCV and problem solved. computer takes a minute to adjust to new maf and injectors but shouldnt be the cause of the problem.

 

[NORCALBANDOG]

Do you have aftermarket headers installed? If you do, then check for any exhaust leaks from the header gaskets. I had an exhaust leak from a burned out header gasket that was giving me backfiring problems. As soon as I changed the gasket, the backfiring was eliminated.