B1 Power Wagon

Can there be such a thing as an RPM specific miss?

My truck runs great, good power, the mileage is still climbing with 17k miles on the clock (16+ mpg mixed town/freeway), no white smoke, no black smoke unless I really get on it, starts easy and idles smoothly.

BUT it has developed this annoying vibration/knock at 2000 RPMs.

I have NO ENGINE mods done. This is NOT the 70 MPH vibration. It happens at any speed in any gear when the engine is turning 2000 RPM. It seems to be smoother when it's cold and becomes worse as the engine warms up.

It feels a LOT like the vibration I had before I had the power steering hose upgrade EXCEPT it is at a slightly lower frequency and is more pronounced.

I ran the truck in nuetral holding the RPMs steady at 2000. Inside the cab, you can feel it more than you can hear it, but it is definitely audible. Obviously, I can hear it more with the window down This rules out any driveline stuff...I think.

This is the same test I did before (and after) having the PS hose upgrade performed and I don't remember hearing or feeling this particular noise.

Here is how I would break it down:

Idle to ~1600 RPMs- Sounds like a diesel I believe this is the RPM range that the pilot injection is turned off.
~1600 to ~1950 RPMs- Fairly smooth
~1950 to ~2050 RPMs- Knock/miss/vibration. It gradually gets worse from 1950 to 2000 and gradually gets better from 2000 to 2050.
~2050 to Redline- Smooth as silk.

Maybe it has always been there and my mind is playing tricks on me after reading about other injector failures? Maybe we've switched to winter blend here in NM and that's causing it? Maybe it's "normal" and is just more pronounced as the miles add up? Maybe it's just me

Fuel filter changed less than 7k miles ago. Oil, oil filter and air filter changed less than 1500 miles ago. I bought the last tank of diesel from the same place I always use.

I'm thinking about throwing a bottle of diesel conditioner in at the next fill up (today). Maybe that will help?

If the mileage was down, if the power was down, if it was smoking I would have already ran to the dealer....but that all seems fine.

Any thoughts? I have a 600 mile roundtrip to take next week. If it's not better by then, I might have to take the wife's mini van

Sorry for the long post

Thanks in advance!!
Tim

bulabula

There has to be about 30 pages of threads on the 2000 rpm vibration. Mine only has a slight vib when the AC compressor is engaged. I guess I don't notice it anymore.

Try a search in this forum using words like 2000 2100 70mph vibration; you'll have lots to read.

B1 Power Wagon

Thanks Chris!

I've been reading through all the vibration posts for the last week or so, well, actually, I've been reading them since before I bought my truck. But, I've been re-reading them over the last week. None of them seem to describe what I'm hearing/feeling.

I had the 1800-2000 vibe when I first bought the truck and the PS hose cured that.

I have never had the 70 MPH vibration.

The truck has been running smoothly since the PS hose upgrade, this knock/miss/vibration has just developed over the last 500 miles or so. It just seems way more prononced then the "normal" 2000 RPM harmonic.

Maybe I'll check the PS hose and see if they are rubbing or touching something under the hood?

Thanks again!