I have a 2005 GMC 2500HD 6.0. I have just put a com cams kit on my truck. The kit is a cam,1.85 rockers,springs,push rods. Also put underdrive pullys JBA headers and electric fans also a aem intake. The truck also has 456 gears and a shift kit. The truck has been dyno tuned a number of times and no one can get it write. Every time it comes of the dyno running good it only last for a day then the truck looses all power. I have tried different injectors, new coils, spark plugs, even gutted the cats. I have no idea what is going on.
Has ayone ever had a problem like this?

 

Welcome to the site.
When the truck looses all power, does it enter REP mode, or just start running poorly?

 

there are all sorts of things that can be happening in the computer based on the tune if the computer sees things its not happy with it will start making adjustments until it corrects what it thinks is the problem every time you flash the pcm it references the parameters programmed in by the tuner and then after some driving it makes modifications to tables on its own so it may very well run good on the dyno and after some driving become a pig. my recomendation would be to find a shop that doed road tuning since you drive your truck on the street and not on the dyno and unless the dyno is load bearing you cannot simulate the load placed on the motor during aceleration.

 

It starts acting poorly. If i give it gas it just makes a lot of noise and moves slow. Like the brakes are holding it back.

 

sound like it is running out of fuel.

 

The shop that was tuning it put bigger injectors in it and made no differance.

 

go get a wide band and see what your air fuel ratio is while cruising around it could be running pig rich

 

Maybe your PCM is not working right.

 

My experience is u tune on the road, and hit the dyno for optics. The track si where u will notice the real before/after in ur times. Dyno is just one part in the process...u shud post ur runs up and maybe someone will have some better ideas whats wrong. R/

 

where you at in Maryland?