bucking while pulling up hill normal? - Diesel Forum

scuffy · 03-15-2005, 03:55 PM

Can anyone tell me if "bucking" is normal at lower rpm pulling a grade? It happens around 1500-1600 rpm in almost any gear when I am going uphill. Truck will do this loaded and unloaded, but it is definately worse when I have a load on it. There doesn't seem to be any noise associated with it, no turbo burp. Once I get the rpms up a little or downshift, all is well. Is this typical of the 6.0? I realize these rpms are not where this engine builds it's power, but what causes this and is it a potential problem? Truck now has 38000 miles on the clock and it has done it at times through it's life.

I am fairly new here, and I did try to find other postings on this subject.... forgive me if I missed them.

ozhoo · 03-15-2005, 06:13 PM

The engine is lugging and can't use all the boost that's being created. If you had a boost gauge, you'd see what you're feeling. You've already found the solution... either down-shift or speed up to keep it from lugging. The 6.0 likes to run a little higher in the power band than a 7.3... shoot for 1800-2200 rpm.

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scuffy · 03-15-2005, 08:43 PM

That is kinda what I figured, makes sense..... I will be installing some guages probably sooner than later, along with some other mods, so I will be able to keep a backwards eye on things. Thanks for the input.

EDWARDWD · 03-15-2005, 08:44 PM

You may have a weak injector.

The following will show a weak injector. Works with stick shift only.

With the engine fully warmed up and trans in third gear let the truck climb a very slight rise at idle. With all injectors good the engine will run smooth. If one injector is weak the engine will slow down and the next cylinder in the firing order will hit it hard. This weak/hard firing will cause drive train windup and the truck will "buck".

EDWARD