I was on the highway last nite going 55

[83countrysquire]

Last nite i was driving on the high way when my car back fired while holdin the gas and it did it as i held 55 and it did it around ten times jerking the car, i have a true duals our the back big exhuast to and short headers why would it do this

[87_crown_vic]

my car did this and it ended up being in need of a tune-up. not saying this is your problem, it might be carb issues.

[83countrysquire]

i ve got tbi and i just had new wires installed less than 1000 miles ago

[87_crown_vic]

wonder if timing might be an issue. my cars are EFI, but they would backfire and sputter until i did a tune-up. i put new plugs, wires, cap, rotor, and cleaned out the intake. check your timing, and clean your carb of any build up.

[Mr. Land Yacht]

yea, that's what I was thinking, maybe the timing is slightly advanced/retarded(no pun intended).
check it and set it at zero..see what happens.

[1987cp]

I've not worked with TBI, but when I was first driving around with my new motor, it kept popping and backfiring (or something!) when I'd get on the gas. I changed the metering rods and springs (AFB carburetor) to give it more fuel sooner and bumped the initial timing, and that stopped. On carbureted cars it's said that a less restrictive exhaust will make a previously correctly-tuned carburetor run lean and vice versa for a more restrictive exhaust, so I'd guess your TBI may be experiencing a similar lean condition because of the better-flowing exhaust system. Bumping the fuel pressure with an adjustable regulator might be able to crutch such a problem, or maybe more extensive retuning is in order?

Of course, I've always thought backfiring was caused by too much fuel and too much timing ... go figure.

[gadget73]

Its EEC III, timing is not adjustable. Check the connections to the crank position sensor. Lots of EEC III running problems are related to the CPS.