bucking problem at 45-55

[ak237]

i am having the bucking problem at 45-55 and have ram my AE and checked PB came back good and reacts like it should when i kill each injector one at a time. fuel presure is good at 70 and wont move even when wide open. IPR reads right arround the desired all the time. the problem is noticeable most when its in 5th at 1200-1500 rpm. this one is stumping me. what should my next step be. all egr and emissions stuff have been removed(EGR valve left in place to not throw codes.

[southend]

Fuel pressure sitting at 70 even at wot is unusual if not impossible. It would fluctuate at least a little. You should check that again, with another guage. Imo. My truck shuddered like that with a bad #4 injector, but I had codes.

Sent from AutoGuide.com Free App

[ak237]

the truck has a fass 150/150 on it there is no posible way to use that much fuel. i just had to put a new motor on the pump before this bucking problem started. this bucking problem is really getting to me its most noticeable when the truck is cold and for abought 5 min after the guage is abought opperating temp. once it is warmed up and i have romped arround on it for a while it seems to have gone away untill i have parked it and let it cool down then it does it again. i did annother power ballance test and buzz test when it was cold this morning and the buzz sounded wered like 2.5 cycles per bank (have video and will be posting when it finishes uploading) what do you guys think really could use some advice.

[ak237]

Buzz test video

IMG_0287 - YouTube

IMG_0287 - YouTube

[ak237]

power ballance just after a cold start

IMG_0288 - YouTube

[anotherhundred]

Mine does the exact same thing. Have you figured it out yet? Ive pulled my hair trying to find what is causing it

[ak237]

i have not this weekend i went through and cleaned the turbo, new IPR and ICP with both pig tales, tested ficm at all 3 situations with a cold motor (48.0 was lowest voltage at cranking) and 8 new glow plugs. the inside of the turbo looked like it was time for a cleaning but nuthing bad enough to make it stick. and the IPR and ICP still looked good no torn screen or metal shaveings. the problem is still there though and is driveing me nuts. when it is warm it runs great and doesnt miss a beat. if any one could help or has any ideas please let me know.

[04cr450]

def. sounds like an injector problem.. Truck running rough when cold and good when at operating temp in a recipe for a faulty injector(s).

[ak237]

how do i test to find the bad injector/ injectors the power ballance and buzz tests seam to be good. the videos of them are attached in the previous posts. i dont want to throw a whole set of injectors at this thing i dont have the money for that.