Big Perm

I'm really frustrated with the power from my truck.

I recently moved from VA to AZ pulling 7000 lbs (trailer and Jeep and gear).

I was not happy with the way it was performing. Now, I wish I had some numbers for you, but I don't have the guages hooked up yet.

But essentially, I was almost at WOT the entire trip. On any kinds of inclines I lost speed. If it was any sort of grade, I would go from my cruising speed of 65 MPH to 50. At a couple of points, I was down to 40 MPH.

Because I had experieced this before, I chose a bit of a longer route to avoid the mountains in West VA and Tenn. I went south to GA, picked up 20 and rode that through Tex-***.

I just think this thing should not be getting passed by the big rigs going up hills. I expected a lot better performance.

I haven't done any mods, but out of the box it performs worse than most Gassers I've seen. Could the problem by my torque converter? The engine sounds great, but it's just not producing.

Is my problem somewhere in the tranny?

A-Poc

Is something getting restricted? Air? Fuel? Are you putting out black smoke when you hound on it? Is it downshifting at any giving point at high speeds?

Sounds like the truck is working fine but something isn't right. I'd check and make sure she's getting enough fuel via the lift pump then move to the air side of things. Check your filter and start your truck and go put your hand by your exhaust to see if you're getting enough pressure.

Big Perm

I don't get any noticable smoke out of the exhaust.

I recently went with a K&N air filter so that should be new. I really don't know the fuel. I mean, it's got little power so it seems like I'm lacking something based on what I read on this forum daily. You guys seem to be getting what this truck is supposed to do.

wannadiesel

The first thing to check is the throttle linkage. Have sombody sit in the cab and run the pedal while you watch the linkage. If the throttle lever does not hit the high speed screw, make adjustments accordingly. You would not believe how common this problem is.

j-fox

It sounds like a plugged up fuel filter.
It could also be alge/bacteria in the tank. Napa sell a biocide that will clean it up. annual treatment is a good practice.
I'd suggest a temperary fuel pressure guage. Hook it up and go for a ride.
I think your truck should stay above 25 psi.

pwrtripls1

All that stuff, or it could be he has a stock truck and stock it only has 160hp/400tq. The old 454 dually's had 450tq and ran a much wide rpm range. Personaly i think in stock form these trucks are dogs. To me, powerwise your truck was doing all it could do.

Like Wanna said, check the throttle linkage first. Then as fast as possible get rid of the stock muffler and at least strait pipe it. Its really not all that loud, and will give you a very noticable power increase. Then give the fuel screw one full turn and up the timing about a 1/16th". Those are pretty conservitive settings and should be safe for towing and around town.

wannadiesel

Not a bad idea, but if you see more than 10 psi out of a stock lift pump be prepared for a cold snap in the nether regions...

Minimum is 3 psi at idle, you ought to see 5 or 6 rolling down the road. Under load you'll probably drag it back down to 3 psi.

wannadiesel

Follow that advice at your own risk. All these trucks are set a little different from the factory. You really should have gauges before touching the fuel screw. I know some people get away with it, but do you want to be the guy who doesn't?

pwrtripls1

True, but for the most part gauges are a given. Just that few crazy people like me who dont mind taking chances. I am in the process of getting a pyro at least. Then when funds permit the rest of the gauges.

Big Perm

I have a fuel filter so I'm going to change that. I'll get the Turbo guage hooked up and drive it around town and let you all know the numbers.

The throttle linkage appears to be fine. I get full extension and it touches the screw.

In terms of the shifting question... it doesn't downshift when I step on it. It will downshift if the it drops below 50 MPH. I usually hit the O/D switch before that so I don't lose too much speed.

So the Torque Converter isn't the cause? I'll change the fuel filter and see what that does for me. I've had the truck since Sept. and haven't ever changed it. I don't know if it was changed before that or not, so that's not a bad suggestion at all.

Thanks for the input!

lovemysan

My truck stock wouldn't downshift to third around 50mph. I turned the off boost full screw 2 turns and it helped immensely. It will kick down even at 55mph. I actually have some boost in first gear and it cut the turbo lag in half. I haven't done anything else other than the NAPA bhaf and a sidepipe. Just that one screw greatly helped the driveability. It was so laggy when I first got it that if I went full throttle @ 50mph the turbo wouldn't spool fully until 60mph. In lamens terms 8-9 seconds.

Micaiahfied

anyone else have an opinion on this.... is the stock muffler really that restrictive? do a lot of people run a straight pipe?

Holsteinman

Micaiahfied, If you are bone stock I would not worry about the stock muffler. Removing it will help a little with EGT's and might give you a little more boost. It is one of the first mod's people do is remove the muffler for strait pipe or a strait thru muffler. Strait pipe might be too loud for your taste.

lovemysan

I noticed very little difference with the straight pipe. The biggest restriction for me was the axle loop and a 2 1/4" pipe holding the tip on. Swiss cheesing the air box was a better mod for me.

pwrtripls1

The stock muffler is reverse flow and only 2.5" in/out. Its VERY restrictive, especialy on a turbo diesel. A 5.9 liter motor just cant flow well or make decient power through a single 2.5" muffler.

At least get a strait through Dynomax 3" in/out and replace the stocker. More exhaust flow gives you more power, more economy, quicker spool, more throttle responce, and lower EGT's.