Isx detuned?

[Rawze]

(11-27-2018 )MKCgrainhaulers Wrote:  ...
the boost will climb to 32lbs and stop instantly and will climb no more
...

It could be turbocharger related...
-- It could be the turbocharger is out of calibration, the air operated controller is going bad, or the filter that supplies air to it is clogged.


What you describe though, is more like the classic symptom of a CM870 silent boost derate. The boost should be 36+37~ish psi.

There are a few reasons for this derate.

Most of the time on the CM870's as a result of someone disabling the EGR in some way and not re-programming it (or not programming it properly) for such things. In this case, the EGT's are usually higher then normal. It sounds like yours are lower than normal.

It can also happen if the ECM fails one of the fueling, metering, or fuel shutoff solenoids. Usually, you get an intermittent/occasional code for one of these components this in the fault history, but on rare occasion, you only get the derate without the code. This can cause lower then normal EGT's as well, as the injection timing could be off.

The engine may have the wrong program in it, or the injection cam timing may be off. - The CM870's in particular have different overhead cam mechanical offsets depending on CPL and ser# range. If someone has the wrong program in it, or if the engine was build (or re-built) with the wrong cam offset, it can throw off the injection timing and other things, making it not run as good, have power losses, have high injection timing leading to lower than normal EGT's, or a host of other minor issues.

I.E.> Only ever reaching 32 psi boost max on a CM870 in particular is a sign that it is not getting full power for some reason or another.


* Check that the overhead cam timing is correct for the CPL / ser# of that engine by wedging the cams and checking it. Re-adjust the overhead valves while your in there, as things could have settled since the initial build.

* Ensure there are no codes for any timing, metering, or fuel shutoff actuators in the fault history.

* Ensure the program matches the CPL and ser# for the engine.

* Ensure the turbo arm is not hanging up or something is causing it to not operate in its proper range.

* If the EGR is disabled on it, then ensure you have a program by one of the guys recommended on here (mommaburt / Unilevers) that tune CM870's specifically, otherwise, your likely to have a bad CM870 program. Most of the bad delete programs will do similar things to what you describe or other similar things.

* Make sure there is no air in the fuel, etc. causing lower than normal power.

* Do an injector leak test on it to ensure your not getting combustion gases back into the fuel system, leading to fuel-starved injectors.


Just some blind guessing here while drinking some coffee, nothing more.