Sluggish 06 6.0

[articrob]

I've have been reading threads on this forum for a while and I have found a lot of helpful info but nothing quite like what i am experiencing.

Here goes... I have a 06 6.0 with 71,500 miles. I bought it used so as far as I can tell it is completely stock. So here's the problem: I have noticed a gradual loss of power over time (four months or so). I can get up to highway speed and hold it but it takes a while to get there. The truck actually accelerates faster if I am easy on the accelerator. When I get aggressive on the accelerator the truck is slow going through the gears and seems to get stuck in third or fourth and sets there with no gain in speed for 10-15 seconds and will actually loose speed (2-3 mph)before shifting. I'm getting 22 psi boost max and there is no smoke on startup or when accelerating. Engine doesn’t seem to miss, no unusual noises. No Codes.

Any Ideas?

[greatbargins10]

mine does this too with 156000 mi. egr delete & muffler/converter delete. Mine also starts to hop like its in the wrong gear at about 50-65 mph especially uphill. never seen anything like it on an automatic. makes me think it's a tranny problem. slow shifting or something until it gets warm. I would like to hear what others have to say about it too. just got this truck last week.

[colo_dually]

To both of you, welcome to the ORG.

There may be issues with the TC locking up/slipping, or the transmission shifting incorrectly with a loss of speed between shifts.

Do you have a monitor system?
Have you verified transmission fuild level, and that the service was done at intervals (30k and 60K)?

Your truck may have been tuned previously, and most tuners (other than SCT) do not tune the transmission, which leads to premature wear and failures.

[greatbargins10]

fluid is full & looks red & clean. no monitor & no idea of when it was last serviced. I'll be changing all the fluids & filters in the next week or so just to be safe.

[articrob]

Paul Harvey page three... Things changed on the way home. As I was accelerating from an intersection on the way home the engine began to run rough and lost power. As I pulled into the neighborhood the engine died, coasted for a while and pulled off to the side of the road. It took several tries to get it started again. When it started in idled rough and i could hardly keep the engine running long enough to get the truck in the driveway. I checked but the engine wasn’t smoking still. I checked my Edge Insight and pulled a P0266 code, no others.
I checked the wiring harnesses the best I could and didn't see any obvious signs of break or chaffing.

[oldhatt53]

I've had an 01 7.3 and an 05 6.0. Both had similar problems. I had to replace the accelerator pedal assembly in both vehicles.

[M90Ranger]

Fuel pressure?

[greatbargins10]

you mean the throttle position sensor? I had one go out on my dodge & it would have a short delay or just stay at idle. but it was not at all sluggish. the 5.9 cummins has a lot more balls on the low end than the power stroke.

[turbotibbo]

if its the transmission id try to disconnect the battries and reset the keep alive memory .....something to try and its free

[57210chevy]

by chance did u just fill
i came up with that code because of gas in the tank
p0266 = cyl 2 contribution/inballence
went ahead and changed injector#2 still had it till i dumped the gas
diesels run like **** on gas better with used cooking oil i recommend neither