I have a 1998 Cummins M11 Plus that has a real bad miss while under load in the mid to upper gears.

Bob tailing it'll miss in low RPM in 9th an real bad in 10th (top gear).

If it were a gas motor v8 lets say, take out 2 or 3 plugs an run it.
Its so bad at times it's jurking an bouncing an the loss of pull up a small upgrade i'm having to down shift to 7th an even 6th at times.

Having to run the RPMs up around 2k in 8th just to keep speed.

Now this might help, if I run it out to 1800 - 2000 from the get go ( 1st - 7th) it sometimes runs fine even in 10th at 1400 rpms, pulls like it should, nice an smooth, but 90% of the time, it's chug-a-lug an good luck getting to 60mph.

PM service done, filters changed less than 1000 miles ago, no change.

Injecter/injecters bad an if so are they that hard to change out myself?

many thanks, Mike

could be a fuel line comming apart restricting the fuel flow. Injectors are too expensive to just try and change them if they don't need it. I would take it to a shop and have them plug into it and see what they say. Injectors shoudn't be too bad to change as long as you know how to set the overhead

I'm guessing a bad injector.

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If its a computor controled engine some of these require special tools that cost big money.Best to have it checked first.

Sounds like a screw up in the Vechile Speed Sensor. If you truck has a top end cut off and having that M11 in it sounds like it would when you hit the top 2 gears the computer begins looking for a certain signal from the VSS and when it gets it BAM shuts off the fuel and if it is wrong would refeed it and cause a miss. Why am I saying this I had this excat same thing happen to me with a 1995 Cat 3406E in a 377 Pete and would hit 10th in a Stupid 10 and all of a udden motor would go apecrap on me. Company thought injectors filters lines I analized and told them look if it was any of them would it not do it in ALL the gears. They were like yes then oless for S&G try changing all the Speed Sensors in this thing they did and took care of it right then.

Sounds like you are getting a mismatch in your speed sensors and your computer is like what do I freaking do. Its Data does not match the program and it is struggling to compute it.

Is this an electronc engine? I can't remember, I don't see enough of the M11's.

Is there any smoke, white or black?

If this is an electronic engine, then you need to swing by a certified repair shop and have them hook the service tool up to the ECM and run a check. More than likly it is an injector, but not garenteed.

I had the same thing happen in a 3126 cat motor.
Took it to the CAt dealer and he put it on the 'puter and found one $23 'lectric thing on the injector that was doin it. Replaced it for an extra $175 and smiled. He also found one of the lobes on the cam was going bad and the valve was 1/4" clearance in it. Might find that one in the Truckpaper soon. Not mine. Driving anohter one now.

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