I have been trying to find a solution for this issue for quite some time. My truck bucks, almost like a hard miss, around 2500 rpms. The bucking gets less aggressive as the truck warms up, but is still bad if I put my foot down. It idles completely fine and if I stay under 2500 rpms you would never know there is anything wrong with the truck. Another weird thing it will do is if I am cruising on the interstate at about 75 mph and I suddenly let off the pedal for a second or two the truck will not accelerate when I put the pedal down again. Even if I floor the pedal when this is happening the truck will continue to not accelerate until about 60 mph it will blow a white cloud of smoke and accelerate again. When this happens the check engine light comes on for about a minute then goes off after regular driving and the truck does not store the code.

I have already replaced the following:
IPR
ICP
All fuel pumps
CPS
Fuel filter

I am trying to avoid replacing the injectors, but what is the best way to test them if this only happens at higher rpm? Has anyone ever run into this problem before? Could it be an electrical issue rather than fuel? Could it possibly be the IDM? Any help on this issue is much appreciated.

Thank you!

 

If the check engine light comes on, there is a code. Most generic code readers will not communicate with the Powerstroke PCM. No acceleration after letting off the go peddle sounds like a throttle position sensor on the accelerator peddle.

 

Sounds like classic injector o-rings to me.

Did your fuel filter look black when you pulled it? Maybe check it again to see what it looks like.

 

Hmmm ok maybe I can download something to my computer and hook up to the OBDII and try to find the code that way. That wouldnt cause the bucking though, would it?

 

Fuel filter still looks brand new, I just went out and checked it.Do you think I should try rebuilding the injectors first?

 

Injector rebuild on a HEUI system should really be left to the professionals. Lots of tolerances and tiny parts that need to be just right.

I was referring to the exterior o-rings of the injectors, the ones that seal between the head and the OD of the injector itself. Those can be done by the average shadetree guy fairly easily, there are plenty of vids on youtube or writeups with great pictures on this forum and others.

 

 

What year truck are we talking about?

The check engine light is probably trying to tell you what the problem is.

You can read the codes if you buy an OBDII adapter that works with SAE J1850 PWM. Torque and Forscan apps are mentioned in this forum. I got the PC version of Forscan.

https://forscan.org/forum/viewtopic.php?f=4&t=6142

This link talks about adapters and why the cheapest ones probably won't work.

I got the OBDlink MX BT off eBay for $fifty-something. It has been reliable. It's $79 new on Amazon, etc.

 

Word of caution, if you do the o-rings, use Alliant o-rings ONLY. They're like $60 a set. If you pay less, I would be skeptical. Don't trust Ebay either

I would definitely see if you could get the codes read before you go throwing parts at it though.

 

The codes might not tell you if it's worn-out or low oil, fuel pressure or a clogged air filter. Stuff like that.

 

 

 

What brand of CPS did you use when you replaced it? It is highly recommended to use Motorcraft or one from International only as some parts house CPS do not ply nice with these engines.

 

 

Another word of caution but you probably already knew this so just ignore me. Before you put all the injectors back in suck the oil out of the cylinders. You don't need to hydrolock the motor. There is probably a write up on it someplace around here.