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Precisionw900 · 07-13-2021, **(Subject: Cm870 vibration concerns )**

My w900 cm870 485 hp with 390k has a heavy vibration at 12-1300 rpm and a high frequency vibration under power 15-1800 rpm. Boost will max at 38 psi, no pyro but installing one ASAP. Absolutely no smoke at all even at max throttle. It’s not a hard pulsing vibration like an injector miss, but more of a buzz that goes away when you let off throttle.

The truck has all new tires, complete new driveline due to replacing a meritor 10 speed with a brand new Eaton 18918b. All that has been eliminated even though I feel the frequency is to fast for anything drivelive related. I just completed a Full egr tune up done and overhead just run.
My local cummins dealer has made sure the factory tune is in truck. (Not sure how much I trust them)

What It feels like is when you advance the pump on a old mechanical diesel injector pump and you start getting power vibration. Is it possible for a factory tune to have too low of crank angle?
I’m a machanical diesel guy so I’m still learning this Isx.

I have spoke to “running rough” some time ago about getting programming checked out but is there something else I should look for first. The motor doesn’t run bad really I just want to KNOW it’s correct.I want to run a leak down test and cutout to rule out a leaking injector but that really should be done anyway.

Should I have programming double checked first ?

Thanks for any input.

Rawze · 07-13-2021, **(Subject: Cm870 vibration concerns )**

will it pass an injector leak test?

ref: http://rawze.com/forums/showthread.php?t...6#pid64706

Precisionw900 · 07-13-2021, **(Subject: Cm870 vibration concerns )**

(07-13-2021 )Rawze Wrote: will it pass an injector leak test?

ref: http://rawze.com/forums/showthread.php?t...6#pid64706

I guess I’m about to find out. I will try to get it in the shop this week and follow up with what I find.

Precisionw900 · 07-24-2021, **(Subject: Cm870 vibration concerns )**

So finally got time to put on a new harmonic balancer and run the leak down test.
Turns out I’ve got an injector leaking. My question is how close to your”a”- “b”- “c” marks are you seeing your bubbles? Mine is starts to push a bubble between a-b but doesn’t fully bubble in cup until “b” passes and compression stroke starts to come off. I bared the engine over 6 revolutions on front and rear bank each to be sure. If that’s considered bubbles on a-b looks like #4 is coming out. Thoughts?

Precisionw900 · 07-25-2021, **(Subject: Cm870 vibration concerns )**

Ran leak test over this morning to confirm, I have 1 bubble build right as “b” mark comes up but no continued bubbling between marks. Barred engine over 6 more revs and same every time. Quick serve states this is ok. Should I still replace injector?

Rawze · 07-25-2021, **(Subject: Cm870 vibration concerns )**

you should not be getting any bubbles.

Precisionw900 · 08-10-2021, **(Subject: Cm870 vibration concerns )**

Update: replaced #4 injector but vibration continues with low power. Ran leakdown test again to confirm injectors and passed also checked all o-rings under actuators while there. It’s actually getting harder to start and runs like it has air in fuel system. Very rough idle after startup for 15-20 seconds and still runs like it’s getting small amount of air in fuel. Pickup tube has been checked and has new supply lines, no air from tank to pump. Thoughts on next step?

Precisionw900 · 08-24-2021, **(Subject: Cm870 vibration concerns )**

So I have confirmed no air in fuel system. Ran a leak down and cutout test. Passed and will run on 1 cylinder all sound the same. Still runs rough at start up for 10-30 seconds.
As I said before my local Cummins dealer was supposed to make sure a factory tune was installed due to an add on after treatment system that was removed from truck. ( ex Cali truck) mechanically it checks out so could they have screwed up installing factory tune? It has horrible throttle response and very sluggish rev. Just want to be sure I shouldn’t be looking for something else before i waste time tuning.

Rawze · 08-24-2021, **(Subject: Cm870 vibration concerns )**

(08-24-2021 )Precisionw900 Wrote: So I have confirmed no air in fuel system. Ran a leak down and cutout test. Passed and will run on 1 cylinder all sound the same. Still runs rough at start up for 10-30 seconds.
As I said before my local Cummins dealer was supposed to make sure a factory tune was installed due to an add on after treatment system that was removed from truck. ( ex Cali truck) mechanically it checks out so could they have screwed up installing factory tune? It has horrible throttle response and very sluggish rev. Just want to be sure I shouldn’t be looking for something else before i waste time tuning.

assuming the truck is not de-leted ...
you can always look in insite and then on quickserv.com to see if you have the program for your truck in there.

if it is de-leted.. then you need to pull a copy of the file out of the ECM and e-mail it tome for a review and inspection to ensure it is safe and correct for the engine.