ISX CM2350 VGT & Brake Table

[Rawze]

Got a chance to see the file he had. It had been done by someone off another forum according to the truck owner, he did not say who specifically. Here are some things I did not quite agree with ...

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* The original factory file he had in his truck was from 2017. It looks like it was replaced by a much older file from maybe early 2013?. - CM2350 files that old have some known issues like injector instabilities and other small problems that got corrected a year later. The file that the person who used to do the delete also has settings in it for an older style of fuel pump with different coil resistances for the regulator. There have been a lot of updates on those fuel components since that file was made. It could potentially lead to erroneous errors with the fuel system if components like the regulator are replaced. Not sure I would have trusted a file that old if it were my truck and I have seen no need to use any file older than 2015 to prevent just these things.

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* Not sure if it was simply the really old file, or if someone purposefully edited it but the engines normal main high altitude operating mode was overridden. The mode that replaced it was high altitude thermal management mode. Also, this operating mode was altered heavily with things like 16% more fueling in places, modified injection timing maps that were as high as +12 degrees BTDC at high torque outputs (this could potentially damage the engine severely) and other things that just did not seem quite right.


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* Besides the one altered operating mode that will only be active above 4000 feet,... there was no correction of the turbocharger operation to compensate for the now vastly different exhaust and intake flow. This the most likely reason the guy was having trouble with it making 5+ psi of boost at idle. Its a typical mistake for someone who is re-programming the ecm to think that the factory programming can compensate for these kinds of changes on its own.

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* Same problem with the injection timing, fuel air ratio, oxygen fuel control, etc. of no compensation at all for the now missing/blocked EGR or the vastly more efficient exhaust flow. I guess the person does not know about the injection processes of the CM2350?. - Unsure,.. but here is a direct reference to the consequences of ignoring these things...
http://rawze.com/forums/showthread.php?t...8#pid15548


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* Not sure if it is the old out of date file, or if it was done purposefully but some of the fuel pump leakage detection during engine run time has been disabled. Not sure I agree with that one, as a leaky injector or relief valve would have to get pretty severe before a leak was detected.

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* cold ambient timing advance has been completely disabled. This easily makes for hard starts, rough idle, + heavy black smoke in very cold weather (below freezing) when the engine is first cranked, but hey, what do I know. I have seen my share of custom tuners struggle with this, as it is one of those systems that simply screws with all your hard work if you don't understand what it wants.


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* The engine is being told that it has to work up to 12% harder to make correct power output in the high altitude operating mode that has been overridden. Why so much effort was put into only one operating mode when there are 10 more to contend with?. I can see it if the engine was locked into this mode and you only drove the truck above 4,000 feet in elevation all the time, but it does not appear to be.

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* The engine brake upper limiting has been altered to weaken the overall engine brake operation by anywhere from 8% to as much as 16% in places in its mapping. I guess that is better than most of the bad deletes I have seen in the past where some moron tries to double it, causing engine damage. - Why not simply leave it alone?

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* The NOx allowance for the overridden engine mode is altered by a high margin and made to be more stringent. I.E> the engine will try to make even less emissions than the original factory file. It seems almost as if someone tried to make it more lenient, but went the wrong way with the table?

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- Other than that, not much else was touched. Overall, it is not a terrible program like I have seen some people do. it has the general appearance of maybe someone who simply does not know a whole lot about what to correct when the cans are axed + egr blocked off on a 2350. There was nothing done about the fall-back emissions that try to reduce NOx, PM, erg fraction, or anything else either. This results in unpredictable injection timing, fueling, altered turbo state and fuel air mix, and it effects power output and efficiency. Not sure about anyone else, but if I were having such mods done, I would want to know the outcome instead of guessing at it.

The engine is still capable of operating in the other 10 operating modes it has. Modes including city, highway, high altitude was bypassed and replaced, extreme high altitude, and others that have not been re-programmed. Also the various thermal management, passive and parked regen modes and other sub-operations have actually not been locked out. I would think the passive and parked regen modes would not become active with all the exhaust component logic disabled, but what about the rest?. Personally, I think this could have the potential to cause the engine to do some unpredictable things down the road when a sensor fails or some other system becomes unhappy.

Some could say that on the opposite end of this coin, M M 2 style programming that locks the engine down into only one (factory non-egr) operating mode is not perfect either. At least with one operating mode, the outcome is much more stable and very predictable. High altitude correction, extreme cold compensation, and various other conditions still happen, but not quite as efficiently as having an engine mode dedicated solely to such environments. Such is the sacrifice that one makes with all those systems axed from it. As long as the total sum of outcome does not shorten the life of the engine or its turbocharger overall, that is what is most important. Second to this is fuel efficiency, because no one wants an engine that sucks the tanks dry unnecessarily either.

If the program he had was not so out of date, had some basic compensation to the altered intake and exhaust flow, had corrected timing advance for the now much more volatile fuel mix, had cold ambient at least somewhat still enabled, and a few other tweaks IN EACH OF THE VARIOUS STILL ACTIVE OPERATING MODES + the passive, parked, fuel limiting, SCR thermal management modes disabled ... It would not have been half bad.

That is my opinion for what its worth, maybe I am just simply full of s#it too.