I have a 2001 F250 with a v10 4x4 thats low on power. ( 124k miles on it. )
Seems to drive "ok"(still seems doggy) unloaded but when i pull my boat(16ft tri hull) its a dog. Flat ground isnt bad, but any hill drops me down in speed fast. When i get on it and it down shifts i loose speed .

Truck Has a 2 inch lift. 35's. Ive re geared from 373 to 430. SPD Y pipe. No catalytic converter. Magnaflow exhaust.

Compression is 125-145 ( all plugs removed when tested) . Fuel pressure is 32ish at idle and 40-42 at WOT.(under loads). No check engine lights. New plugs. Fuel and air filter. Fresh tranny service.

Its been to 2 shops and the tranny shop. They say all is good.

Ive pulled about 7000k behind the truck off and on and it used to pull great. What gives? Any ideas?

 

You clean the MAF? Check for possible vacuum leaks?

 

MAF was cleaned when i changed the filter( And it responds as it should on my scanner) . No vacuum leaks. And it holds steady on the gauge at an idle.

 

What did you use to check for codes? I believe that some early years of the V10 can have codes or issues that do not set off engine light or a code. Some codes can only be read with a professional reader. Did you check or replace any coils during plug change?

 

I agree with Diamnd1 above. These 6.8's can have one misfiring cylinder and it's not too obvious.
If you carefully feel the engine, a misfire will create just a bit of stumbling when idling.

 

I was planning on replacing all the coil packs next. But was looking for other options. The scanner used was a snap on my dad owns. And a Cheapy I own I paid about 400$ for. The truck seems to have a slight roughness while sitting idling . But nothing super noticable. I was told that sometimes coils can begin to fail but are hard to notice at higher rpms and won't throw a check engine light or code

 

Replacing all 10 will be pricey. If you can find someone that has a prof. scanner, it may indicate which are bad before dropping coin on all.

 

That's why I took it to a few.shops. they told me everything was good and that the v10 is just a dog. They said everything was within spec

 

I've had bad cop's that wouldn't pop a code until I really stomped on it accelerating up an on ramp.
Keep in mind that coil pack springs will rust out, especially after they get a bit of moisture in the hole due to slight manifold leaks.
We had to replace my brothers 7 or 8 cop and it was almost in pieces when we pulled the boot off.
If you have an IR test or, a misfire will have a slightly cooler exhaust manifold temp.
You have a good obd II test or to detect any codes present. No need to spend more money.

 

All the boots and coils looked good when I replaced the plugs.no rust all dry ( I live in az humidity isn't a problem) I've been really getting on it alot because I have to or the truck won't move.. so still no codes. No stored or pending.

 

Edit I see you don't have a Cat..

 

Will a bad injector make the check engine light come on?

 

As I stated earlier, I really had to get on it to finally pop a code.
In CA, an emissions related issues will activate the cel, eventually.
Not sure if the same applies to AZ programmed vehicles.

 

Went to start it this morning. And it was really stumbling , still no CEL. But seemed to smooth slightly out after it warmed up. I drove it like I stole it on the way to work . Still a dgo and seems like the torque converter was jumping in and out in 2ND and 3rd from.1200 to 2500 rpms

 

A bad cop will give you that tranny feel you talk about.
If not a fuel pressure issue or vacuum leak, it's got to be a cop/plug issue.