Vibratioin at 30psi and around 1300 rpm

[Trucker66]

I got a 2014 T680 with a Cummins and had it "tuned up" last summer.
During the tune up I had the HP bumped up from 485 to 550 hp and the torque bumped up to 1850 foot pounds.

Right after that I started getting this vibration on every hill once my hp drops to approx 1300 and my boost is always at 30 psi. As soon as I let off the throttle it will stop.

I can't figure out where the vibration is coming from. It feels like it's a torque issue but I have no idea where it's coming from. Maybe clutch, drive shaft? rear end?
I just turned 400,000 miles and I had the transmission oil and rear end oil changed and there were shavings on both rear end plugs..
On the valve cover it's rated 485 HP and 1850 ft # but it was set at 1750 from the factory.

The engine was rebuilt at 330,000 miles due to bad rings and liners and thats how I found this site. After the tune up its been running like a top, not a single check engine light. Just need to figure out this vibration issue.

[Nilao]

Bad injector maybe? Low fuel rail pressure. So many things could cause a vibration. Even a possibility that the wrong calibration was put into the ecm? Just because it goes into an ISX doesn't mean it fits into your ISX.

[hhow55]

When mine did this, it turned out to be carrier bearing. Funny thing about a carrier bearing, it can look to be good, but just a little slack in it can cause vibration issue like you have.

[DKenworth]

Well, i think that it could be also a input shaft on tranny where the carrier bearing seats, I would not reccomend to bump up engine HP and torque, maybe only up by 25HP. Cause ur mpg will go down for sure, and a lot more stress to ur engine head, pistons... clutch... I think theres a difference in heads for 485HP or 500+HP. ( I Wwould love to hear what RAWZE will say about this) Well, now u can start from drive shaft bearing under sleeper, check if there is a not a lot of play, that is cheap fix. If not this than its going to be ur carrier bearing or imput shaft.

[marek4792]

While checking the carrier bearings check your driveshaft ujoints as well

[Trucker66]

Thanks for the advice.

I was leaning toward the carrier bearing to. When inspecting my u-joints I noticed play in it but Master Fabricators in Augusta (specialist in drive shafts) said it would do it all the time, so I'll go ahead and change it because for $100 or less I can eliminate that off the list. They also said some play in there is normal which seems to reason since its polyurethane bushing.

[Unilevers]

too low of final crank angle? i dont remember if i did yours but cell/txt/pm me if i did and i can have a look at it again to see.

[Shotgun74]

Trucker66 did you get your vibration problem solved?

[Trucker66]

(05-01-2017 )Shotgun74 Wrote:  Trucker66 did you get your vibration problem solved?

Not yet, I hope to get home this weekend and get the hanger bushing and see if that helps. As soon as I do I'll update this and let you know if that was the issue or not.