i have only had the truck 3 weeks, 06 5.9 mega cab 40,000 miles.

any way engine light went off last week dealer checked it yesterday and found nothing wrong, I got about 10 miles and it went on again?

The only thing that i notice is the turbo whine is seems more noticable all the time and the rpms seem highter 70mph 2200rpm wiith 265 tires.

is this normal

 

I would have to hear the turbo noise to confirm or deny normality...I would get a 2nd or 3rd opinion, and not with a Dealer.

If I had a dollar for everytime Ive heard "The Dealer couldnt find anything"!

 

is the silencer ring removed ? you should check to the codes yourself or take it to a auto store and have them scan the codes. could be a boost leak.

 

Ihave an 07 and i pulled the silencer ring out of the turbo and got rid of the baffle between the intake and the turbo and it made the turbo noise alot more louder, it will not hurt any thing just sound better if you like turbo sound.

 

You can check the codes yourself by cycling the key off to on 3 times, leaving it on the 3rd time (without cranking the engine). The codes will flash on the odometer screen.

 

RPM's sound about right if you have 4.10 gears...

 

The problem with the higher RPM was suprisingly from installing a remote start that also caused engine light to go on and the gear selector desplay to loose the indicator box light.
Must have been keeping the torq converter from locking up at higher speeds.

 

I was wondering if the trouble may be from transmission. If it is starting to slip your RPMs will move. I would at least check fluid and if you are not sure if the fluid was serviced from the previous owner, I would change fluid and filter to see what it looks like. Better safe than sorry. Best of luck...

 

Silencer ring removal and airbox mod would be the first thing I would check.