SamuelsonMotorsports

iTrader: (1)

Got a 07 NNBS Duramax that has a built trans (now) and recently got a new tune (trans left "stock" programming) but engine is +270.

Anyway, before I dropped in the new tune to the DSP5, even on the 150 tune the truck will display "reduced engine power" with no codes. No idea why.

Was running factory intake, changed to S&B dry filter (thought it might be a restriction issue) and fresh fuel filters on FASS 150. Replaced the MAF (didn't change ****) and replaced accelerator pedal (didn't change ****) and I'm out of ideas.

Used to easily get to 140mph, now it struggles past 85 thanks to REP.

Doesn't throw REP codes in position 1 (stock tune file) but still slower than hell.

Fuel pressure at WOT is 26K and I do not have the rail plugged or shimmed, but I pulled off the return and made a few WOT test runs and had nothing in the jug, so its not bleeding pressure.

Boost (after changing the stock bridge to a pusher Y bridge and pipe) dropped from 30+lbs of boost to 26lbs of boost (boost being a measurement of restriction, less restriction, less boost seen) but picked up power everywhere so that's not it....

Problem started before trans went out so I thought it might be trans related, but after new built trans, does the same thing.

Injectors look good and I do have ONE injector thats 3% in park but good in idle so that's not it either...

Any ideas? I hit the basic 4 "REP" causes and get no codes, good rail pressure and boost.

Tune maybe?

1FastBrick

iTrader: (17)

Not sure if you got a tune from a reputable tuner or elsewhere.

It's tough to go over 150 on the Dmax with out upgrading things. Like larger injectors, modified turbo, and so on.

I suspect it's running out of fuel.

I had a DSP 5 tune on my 05 for a little while. I didn't have a lift pump and it would run out of Fuel on the top end. The trans started shifting harsher and harsher with alot of defuel between shifts. I finally got sick of it and Had it flashed back to stock. The trans was stock and I didnt want to risk breaking it.

Since I purchased it used and it had few minor mods, I suspect it may have had a handheld tuner on it at some point. The tune appeared stock But I have heard some hand held units don't return the full tune back to stock as well as the adaptive values need to be reset and this is not something they are capable of.

I had mine flashed with GM software through a tech I know as well as we reset all the adaptive values. I want it to live till I can afford all the mods needed to support the mods I want.

SamuelsonMotorsports

iTrader: (1)

Thanks, but it's not a fuel issue. I have a FASS 150 with fresh filters and I have power loss all across the board in stock, tow, daily driver, semi and full "race". There's either an electronic issue not triggering a code OR the tune is bad.

Gonna black box it in the next couple of weeks and review data again.

So far-
GREAT rail pressure
GREAT boost pressure
NEW air filter from S&B, NEW fuel filters from FASS, Injectors show good on feed rates.

Just runs like it's missing power. Barely turns tires in stock mode on semi-wet pavement. (There's no traction control system on my truck)

It started before the old trans blew so I thought it was trans related BUT now I realize either my pcm is corrupted or something electronic is being a shitbird.

1FastBrick

iTrader: (17)

Have you had someone look at it with either a Gm scanner or a something else like a snap on scanner???

Is possible there is something stored in the history that your not able to see on the surface with any other type of generic scanner.