Living up to my avatar tag line (I'm a cautionary tale), I've unwittingly done everything I can to sabotage my shiny injectors for the last fifty thousand miles. Air in fuel, soot in oil, pressure spikes, loose injector bolts, cracked cup - you name it. Full Force Diesel has backed me up all the way, and I'd have to say they've gone beyond what I would call good financial practice - they have some skin in Stinky too.

I said all of that because I don't want anybody thinking for a second that this is about the quality of a product or service - this is about abused injectors and sorting out the mess that I may have created for myself. I am unsure of what the root cause is, but I have finally eliminated all the other distracting shakes, rattles, and rolls in the truck.

The symptoms: The engine idles glass smooth, and I'm not abusing the term. If I put a beverage on the console, you'd be hard-pressed to catch a ripple. Put it in gear and life is pretty good until the oil warms up and the ICP starts approaching the 1000 - 1500 ICP range, then the engine shakes like I've lost compression in one cylinder, the engine is unbalanced, or I lost a stick. I can rev up in neutral (parking lot or at any speed while coasting) and I get no symptoms across the tach, but put it in any gear and add a load to the magic ICP range, and the truck shakes pretty good. A little more or less throttle rids me of the shakes.

This wouldn't be so bad if those ICP pressures weren't the exact range for cruising on the highway - with the apex of the shakes at 65 MPH. The shake comes and goes, and I see a small imbalance of 25-50 degrees on the dual EGTs when it happens. I could have one hot stick on the passenger side, or one cold stick on the driver side.

I speculate I have one imbalanced stick at that pressure range, but I can't rule out a possible dynamic at a specific torque range either, like maybe the rear end is at just the wrong angle - even with ladder bars. I also can't rule out a transmission thing - but the transmission has recently been checked out and had the fluid/filter change. The shake I describe was there before the transmission service, and I was hoping the shop might find something there - to make it simpler. This is also a pretty specific range of boost/backpressure.

All I have in my thoughts are to build a break-out box for the injectors, with a long-enough cord to reach the cab. Is there any expert feedback out there or really good questions to ask me?

...uh... To hell with the "really good question" prerequisite, hit me with silly questions - it might jog a thought process that I've skipped over.

 

I hate to ask this but as a hunch how bad does this get on a 1-10 scale when warm and such conditions apply?

 

If you could identify specifically which cylinder/s are giving you the vibro action it may help to make sense of whats going on...

I dont remember if you had ever gone to a fuel pump with more oomph than the factory one?

Is it possible at that specific rpm range under load you are actually experiencing in real time the effect of how our engines consume fuel...? I remember something vaguely being visitid on this subject a good long while back talking about 2 cylinders that fuel on the same bank right after eachother that could lead to a potential pressure drop in the 2nd injector in the sequence?

Just taking a stab in the dark...
It seems like you have done pretty much everything doable to test your injectors for proper operation... and the last time you compression tested everything checked out correct?

The only other thing that comes into my fragile little mind is yet another stab in the dark in the direction of valve float at that rpm range under load...

 

I thought AE could do cut out, I am guessing I was incorrect on that.
Can you run a contribution test while in the conditions you describe, I am not sure how AE does that. With some OEM diag tools you can run the test anytime you like which helps for issues like that.
Long stretch of road with a broom handle on the go pedal?

 

An contribution test can only be perform at idle and in park (on out of gear with E-brake applied) I seem to recall.

 

I did some reading on the AE test and I see its not actually doing the testing but signalling the PCM to, Bummer.

 

Yes, all the tests are performed by the PCM, and there's no provision to cut off an injector electronically. It has to be done by physically interrupting the circuit, either at the connector, or with a breakout box. However, that's a pretty good way to narrow down an injector problem. If you watch mass fuel desired while cutting off an injector at a time, the amount should rise about the same amount when each injector is cut off. If an injector being cut off causes little to no increase in the MFD, it isn't contributing much.

 

Can you watch perdels while driving?

 

I like Christof13t's suggestion about the fuel pump and possible lack of fuel to the injectors. One question would be since you have AC injectors and the T444e use's them what if any is the difference in flow rates. Another thought would be and this is with no disrespect to your tuner is it possible there might have been a digit slip somewhere along the line. I know nothing about tuning or what is involved but could it be possible?

 

Friday the 13th hit me upside the head, I'm going in to work now. I see a lot of great questions in here... I'll get to all of them after work.

 

Injector imbalance is most prominent at idle. If the symptoms do not occur at idle (cold or warm), then it's not an injector imbalance issue.

Above idle and cruising it's going to be another problem, and that can be just about anything: tuning, transmission, driveline, etc. This is what you're experiencing when you compare just revving at idle vs driving.

In a rough way, the ICP can almost be correlated with engine load (again, revving vs driving). As engine load demands increase, so does ICP. In terms of tuning, if timing is slightly off at certain ICP levels and engine loads (especially on single shots, and extremely common on singles with very large nozzles) you can get engine vibration, shakes, shudders, choppy sound, etc. Also it can coincide with other issues elsewhere in the transmission or driveline, where certain engine loads put everything in the correct "synchronization" to start vibrating or making noise. Change the load again (higher or lower) and the synchronization is lost and the chatter fades.

There's no real easy direction to point you in, especially on a forum. You can start by carefully monitoring mass fuel, pulse width, ICP and duty cycle, etc at various times to see if you find certain anomalies or triggers.

 

Yes... I have been known to be OCD at times, but this registers a 4.5 to a 5.0 on the seismic scale (I've been in a few of those).

I still have a new OEM, but I'm not looking at WOT performance here - this is cruising on the highway. The fuel pressure averages about 58 PSI (I think it's the FRx black spring). I'm in the process of thoroughly testing the fuel flow and possibility of air in fuel. No real signs of problems yet.

The firing order can lead to a problem at the 6-8 combination, and I have "diesel flutter" in my exhaust. This is when the harmonics are just right to make a soft pulse-jet sound out the exhaust. My homework shows this is because of the way the exhaust shock waves synchronize at the collector with our firing order and the design of the up pipes. Single shots with big nozzles create more "shock" in the exhaust. In other words, eliminating diesel flutter would involve a major redesign of the hardware before the collector, or changing the injectors.

Compression is quite good (during the test at 180 degrees) - 400 to 425 PSI, with 7 being the lowest.

Valve float - maybe at higher RPMs, unless you are thinking of something different than I am.

The Cylinder Rotational Velocity can not be seen above idle to get PERDELs. The CRV is used in the Cylinder Contribution Test.

Yup.

This is true of all diagnostic tools - they just send the command to the PCM/ECU to perform the tests programmed in at the time of manufacture.

The 6.0 has this test written into the PCM - I wish we had that. I'll be watching the MFD from now on.

Stinky was live-tuned, but I later learned I still had issues with the fueling when he was tuned. Since I've done more changes after the live-tuning sessions, there is a very high possibility I pushed the tuning off the edge. It would show no disrespect to Cody if my tuning is no longer optimized now - that's on me.

 

You can bet on it. Thanks for this information.


More intel! I found I still had one last distracting vibration, but it took a long haul to discover it. I do fine for the drive to/from work in most cases, but that's limited to 45 minutes to an hour. The vibrations reared their head without the EGT spread and I pulled over to a gas station under the cover (raining). The passenger rear rotor was hot.

Next stop, Bosch rotors for the rear. The fronts were swapped out for OEM last weekend and that helped - but nobody had the rear OEMs in stock, and I'm on a calendar count-down. Hooray for Anti-Seize from the last time I was in there, it took 90 minutes for a full rear brake job (omitting the parking brake shoes - they're fine). The slide pins were still good - another "Tugly moment" was at play.

EBC slotted rotors - you have to use the EBC pads with those. I didn't know that at the time I did the brake job, and my semi-metallic pads made a mess of the whole affair. Another member pointed this out recently on another brake thread, and I confirmed it locally.

I had another issue with something not feeling quite right in the wheel - I felt engine vibration. Being thorough, I looked for anything that could possibly transfer engine vibration to the steering wheel shaft. There is was - my shiny new power steering pump pressure hose was rubbing on the shaft. The hose free-pivots, so I couldn't loosen it and re-position it. I covered it with split-loom and zip-tied it to the power steering pump return line and the steering wheel shaft is clear.

I still have to test-drive the truck after these changes, and I'll report back.

 

I had the same thing happen to me I replaced both sides. Amazing how much rotors can hang and give you weird vibrations. We hardly ever look at the rears as suspect. I have a RF that's starting I think cause I am starting to see the darker brake dust on the wheel.

Good catch I was sure you knew it was not injector related as you have done your cups and seals enough I was thinking a hot valve going but you ruled that out with your CT numbers.

 

Will come as no surprise, but that's 3 and 8. Both are downstream in the fuel rail from a cylinder that fires before them, so they will always have slightly less fuel pressure.

Rich - as usual, looks like you found the problem.

I'm coming to the school of thought where any rotors, even cheap white box crapola from china, is fine. As long as the rotors run true it's all about the pads in any given configuration. Hawk LTS or Superduty, or EBC equivalents, and not ceramic. OEM is good too.

Pocket got me thinking your vibration could be CPS related. If it continues might be worth swapping to something else and take it for a, er, shakedown run.