Ford's answers to the NHTSA 6.7 Investigation

Huntindog wrote:
Back the the pulse timing of the pump.

In a gas motor timing of the spark (what triggers combustion) is advanced by the distributer (or computer) as rpms increase.

In modern diesels the timing is controlled by the computer sending signals to the injectors (which triggers combustion). Diesel burns slower than gas and I am sure is injected slower than the speed of a spark in a gas motor....So I surmise that signifignant advancing of the injection would be required as rpms increase.

For some reason Bosch wants the pumps pulses to match when the injectors fire.....But unless there is some sort of advance mechanism built into the pump (I don't think there is) it is impossible for the injectors/pulses to stay in sync.

The 100,000 dollar question is: Why does Bosch want them in sync?
If it is to prevent cavitation, then we could have a failure cause identified....And just as importantly a retrofit kit would be possible.
I would think that a properly sized accumulator tank should be pretty simple to plumb into the existing systems.

I am not suggesting that this theory derail thinking of other possibilites, just that this one be fully explored

I am not sure if Bosch wants them in synch or not... but I am pretty sure that Bosch wants the pressure near or at the peak requested for what ever rpm, load, etc before the injector is required to fire the first of many pulses. As long as the pressure is there before the injector is fired by the ECM, all is good. Bosch is aware of resonances in the plumbing from the rail to the injectors, they have a retrofit program going right now on VW's they install a rubber donut that is half way from end to end, to stop the vibration frequency that was causing the number 2 injector line to fail. As to how these waves transfer back to the pump, sort of like how cones, tapers and lengths control back waves on a high performance 2 stroke motor when it comes "on the pipe" with an expansion chamber, is beyond me, but I am sure there are pressure waves being sent back in pulse form to the HPFP. Whether it is checked by a one way valve with a ball seat or not, or causes failure of the ball seat, I do not know.

These motors have crank sensors, the ECM controls timing by a host of methods, many fueling injection maps based on all kinds of parameters. To my knowledge, you can plug in a Scan Gauge II, and it will tell you the timing advance with one of it's 4 monitored choices, based on load, throttle setting, rpm, and on and on and on.