I've noticed that my truck seemed kinda sluggish lately and today when I floored it it seemed to take a really long time before shifting into O.D. I pulled the K&N to clean it and it was really really filthy. Everything beyond it is clean and dry of oil so it must be walkin the walk. Anyway I dropped in a stock filter while letting the "drop in" dry. It's still pretty sluggish....my next guess is a dirty fuel filter.
Any reason to think that the ULSD is causing problems??

 

Dirty fuel filter doesn't help, so good move on that - try some power service\equiv Cetane additive + 1/2oz ashless 2-stroke motor oil per gallon of fuel - see if that doesn't help a bunch

 

Yea changing the fuel filter did a lot. When I floor it "unloaded" I would get about 28 psi in boost. After the fuel filter change I'm getting 35psi. with a stock air filter. I'll be putting my K&N back in now that it's dried.
I've run power service before.....never really noticed any difference. I run Howes "Meaner Diesel Cleaner" and I see a really big difference between running it or just straight diesel.
I think I'll add the outboard oil on my next trip to Wally World.

 

You notice any increase in EGTs with your sluggishness prior to your filter change? Just curious as I am trying to track down a problem but the truck doesnt appear to be sluggish and the filter is not that old.

 

Not really.
I have noticed an egt increase when air filter is plugged.

 

when my fuel filter gets old it will do what you described, i can go WOT and the boost will fluctuate up and down

 

Huh, do you run a fuel pressure gauge? Curious if you saw any differences in fuel pressure at the point performance dropped off a bit

 

I don't have a fuel pressure gauge.

 

After adding a pint of TCW-3 as well as changing the fuel and air filter things are much much better. I still have a lag off of the line but I've had that for a really long time. Not sure what to do about that problem.

 

I noticed my truck was starting to lose power as well. The smoke was more dark gray than black, EGT's were a bit hot, and it just didn't have the power it did a few days prior. It was time for a fuel filter change so I put a new one in today in the parking lot at work over my lunch break. Man, what a difference! The truck feels more powerful than ever, the smoke is solid black, boost is up a few notches, EGT's down a few.

My lift pump has also been clickity-clacking over the past month or so, and the filter change resolved that as well.

Amazing what a $30 filter and 10 minutes can do.

 

Yeah I had just cleaned the air filter prior to posting but hadnt run the truck yet. That helped it out for sure. Might change out the fuel filter as well.