Mxs backfiring /popping exhaust

i drove an 05 with isx. backfiring out the intake. at night, you could literally see fuel spitting out the air filter cans. from the headlights behind me. the problem acted in the same manner as yours. but only around 1100 rpms. never had the problem after the overhead. but you did yours twice.

if it were a car. i'd say lean air/fuel mixture. (low fuel pressure) or bad exhaust valves.

maybe have a dyno done. so the mechanics can duplicate your problem. with any luck, they can determine which cylinder. or at least, have an idea of what to look into. rather then replacing parts after parts.

 

Has the camshaft ever been changed in this truck? Has the ECM been updated recently with a new file? If you say yes to either of these questions.......you may have the wrong cam in versus the file in the ECM. I've seen CAT engines backfire through the exhaust due to this.

 

You my be able to narrow it down with rack reading on cylinder cut out test. Run engine off 1 cylinder at a time. Just a thought currous to find out.

 

Cylinder cut out if it's a problem with one cylinder even mechanical it will show. The ivas can cause this.

 

i have a 625mxs It done the exact same thing when it was 2-3 year old and so did my buddy's truck also 625mxs , best I can rember it was something with the IVA ........bad solenoid ........I think ,may have been jake head cracked , I ran truck for a few months like this until it got bad enough to show up ,