55mph backfire

[supa6t]

under full throttle at 15 pounds of boost just after the car has shifted from 2nd two 3rd the car begins to backfire and miss not sure what it is after i let off and get on it again its ok and when i am on the high way it seems ok just at about 55mph it dose it. i have replaced lots of things and cant seem to find it i am lost please help.

 

[supa6t]

can someone give me some thaught or something i am lost with this i puled the plug the are not fouled there lite tan so i dont know what it could be

 

[NASSTY]

What have you replaced?Do you have a scan tool?

 

[dow j]

lot of times it will be a bad coil pack,check the ohms,should be between 11 to 13,more than likley secondary ignition.Cam sensor will cause this as well.Jim

 

[supa6t]

i have checked both of them there fine i have checked every thing i know of to check and replaced mass air 3 times wires plugs fuel pump filter wires new coil and module. could it be computer or chip related

 

[ULYCYC]

What are 46# injectors?? (listed in your sig)

 

[77tech9]

Maybe has something to do with your TCC locking up and when you back off it's cranking the engine over on it's own.

That could cause some backfire in some cases.

 

[humberto]

Never heard a tcc locking up causeing backfires.Try another chip and check both bat cables they tend to fail alot of times and will cause what your describeing.Good luck.