My Truck is having some afterfire in the top of second gear. If I am just cruisin in town and the truck doesn't quite **** to 3rd but stays in the top of 2nd for any amount of time it begins to sound like a semi automatic rifle. If I get right on the fuel it doesn't do it and if i'm in the lower rpms it's fine. What could cause this and what is a recommended fix? The truck has a rebuilt transmission , new plugs , wires and new exhaust with longtubes. It only seemed to start doing this after the trans build if that makes any sense . Thanks in advance guys.

 

Possible O2 sensor failing?

How many miles on the truck?

 

Brand new O2 sensor .

 

At what RPM is this happening?

 

I guess I'm stupid! But , what the hell is after fire? We talking about pinging or the rev limiter?

 

It does make sense. Could be a pinched crank sensor wire or it got hit installing the new tranny if it wasnt removed prior. Just a thought.

 

I don't know too.

 

http://en.wikipedia.org/wiki/Back-fire

Typically a small engine term. Motorcycles,lawn mowers ect.

 

A for effort, but, NOT!

 

Not for what please explain.