Little bit of background - my last Dakota was a 97 2WD SLT with a 5.2L in it. It appeared to have been lightly modded before I bougt it, with at least a flowmaster exhaust, but everything under the hood looked stock. Regardless, it had tons of torque, would haul anything I threw at it, and was no slouch accelerating onto the highway or passing.

I sold it last year and moved up to another Dakota. This time a 2001 SLT quad-cab AWD with a 5.9L, bone stock. After test driving it, I was kind of disappointed that it had nowhere near the same torque or oomph behind it as my old 5.2. I figured it probably just needed a good tune-up or maybe had some old gas in it, and I liked everything else about the truck, so I bought it anyway.

Since then, I've done a full tune-up, with new plugs, wires, distributor cap/rotor, filters, injector cleaner, cleaned TB, flushed and re-filled all fluids, etc. It runs smooth, never hesitates or misses, no codes, and doesn't seem to have anything major that is obviously wrong with it. It even gets good gas mileage. It does have a tick that develops under load after it warms up that I suspect is either a sticky valve lifter or an exhaust leak, but neither of those should really affect power.

My only lead at this point, other than "that's just how it's supposed to be", is that I can hear a faint sucking sound under the hood when the engine is under load. I suspect this is a vacuum leak, but I haven't been able to find it. I've replaced the PCV valve and the breather fitting on the opposite valve cover, and inspected all the vacuum lines I can find, but without success. Reving the engine at idle doesn't produce the sound, so it's proving difficult to find.

I had expected a slight loss of pep due to the extra weight of the larger cab and 4WD, but not quite like this. The truck can't even pull itself (no cargo or trailer) up mild hills at a 70mph cruise without downshifting. Taking off from a stop with the accelerator to the floor is pretty disappointing, and that much different than taking off normally. Is this really normal for a 5.9?

So where should I start? Exhaust? Cam? Twin turbos? Maybe something more repair oriented?

 

weight for one. and 4x4. i would start with intake, larger tb and exhaust. depending on what you want then cams and a tune.

 

What gears did your old truck have and what does the new one have?

I put an np242J transfer case in my truck which has 2wd and AWD selections. The truck pulls about the same in either, so I doubt its the AWD that is causing your lack of power. Weight is definately a big factor, but gears are too. For example, if you had 3.90s in your old truck and you have 3.21s now, that will make a night and day difference for off-the-line torque.

So my suggestion for a good place to start is re-gear your axles.

 

Before you go blow a couple hundred on worthless stuff, why don' t you make sure it's right?

 

b/c thats the sensible thing to do

 

That's a good thought. I hadn't considered gearing. It's a little late to check my old truck, but how would I go about determining the gearing in my current one?

That's sort of what I'm trying to do right now, by asking for advice.

 

What are your RPMs at 70mph?

 

theres a sticker in the glove box that will say 3.55 or 3.92, my bet you have the 3.55

 

Just went for a little jaunt on the interstate - 1900rpm at 70mph. Also checked the glovebox sticker and it confirmed a 3.55 ratio.

But I recall my old Dakota was just about the same on the highway - right under 2k rpm at 70. I could be mistaken, though.

Could that really be all it is? When a V8 truck can't even keep itself from down-shifting to go up a small hill, it seems like there has to be something going on.

 

i doubt its the gear ratio. could be something with the tps or tv cable. but i dont really know.