Alright, i've been chasing little things with this truck for the last couple months with no success, so tell me what advice yall have for me. Truck is an 06 dually with around 77k miles. Trouble started around 60-65k. First problem is, truck runs pretty good empty(still seems a little under powered compared to my first two, but runs ok to someone who doesn't know better), but when I hook up to a trailer, especially anything over about 5k pounds it will run up to about 35psi then the boost will just drop off to under 30, and just pulsate there. The truck loses power completely and I can barely hold speed on the hwy, as well as egts peg and I have to let off. Can't figure this out cause it will make 40lbs of boost empty no problem.( Well it would before the second problem started). Now new problem, while chasing the first problem we(me and john up at TDP), thought we'd try a different tune on the smarty to see if that made any difference. So loaded TNT/r, and I'm running it on level 1, with pod on 80. RP default, timing 1, wastegate off, TM 2. Don't really notice any difference, except that now it won't make over 35 pounds of boost at all and still falls on its face when it hits that point. But now it will also make a p1222 code when towing,the wait to start light comes on and dings at me, and it will completely lose power even worse than before and struggles to pull a 16ft landscape trailer. Will run like that for awhile then the light goes off, goes back to running like before. Basically all this happens when I'm towing though, which is about 85% of the time that I drive my truck. So I took everything off, and put it back to stock to see if that made any difference. Feels extremely sluggish and can barely take off in second with a trailer of any weight. Still makes the p1222 code and is just a dog in general. I took it to the dealer and they pulled all the injector lines, retorqued everything and said it was fixed, then I picked it up yesterday, and as soon as I got home and hooked up to a trailer and got on the hwy, p1222 code again... no power...??? This thing is driving me insane. Any ideas or help yall can offer me would be greatly appreciated cause I'm bout ready to drive it off into a lake. Really sorry for the extremely long post, just wanted to give yall a background on what i've been dealing with and what its doing.
Thanks

 

It sounds like to me like the wastegate is holding well up to your 35lbs of boost then pops open all of sudden and drops your boost pressure to something considerable less than 35 lbs. The EGT's peg because you lost your air and were still pumping in the fuel. Now in an overly rich condition, excessive fuel in the holes skyrockets the temps and kills the power. Unless you lift off the throttle and let the wastegate slam closed, you'll never get it back under power.
Taking off in second gear pullling a trailer is just lugging the engine, no boost, no rpm, no power, so it would naturally be a dog. Leaving in first pulling the extra weight, even an empty trailer or lightweight trailer would still better since you develop RPM and BOOSTwhich cool off the EGT's.
You have 35's on there as well which only makes matters worse since now you've effectively made the rear end ratio worse for pulling anything hooked to the bumper. LOL
I suppose now that you've bounced the wastegate valve in the turbo housing it might have a small leak internally (burnt) in the seat and instantly looses pressure as you throttle up on it.
Just my outside thoughts, take it for what it's worth.

 

Ok but what about the p1222 code and loss of power there? It seems like the 2 problems are linked. And ya I understand lugging it and stuff taking off in second. But at the same time, I also know what one feels like when its running right and when its underpowered, and this one is definitely underpowered. When I'm pulling a big load I always take off in first, but pulling a small landscape trailer, my last 07 had no trouble taking off in second, and this one did'nt used to until all this stuff started. I mean this truck has trouble pulling its own weight. One example just to prove that point is that my buddy has an 06 dually setup identical to mine, and we hauled a bunch of hay down to fort davis. Both same load, same weight etc, and his was stock, while mine has the smarty, intake and exhaust(this was before the tnt. I had the smarty revo on 3.) And he was runnin off and leaving me the entire trip, while i was sittin back losing speed with my boost gauge pulsating and egts pegging. Theres definitely something wrong with it.