CM 871

[Rawze]

As far as the injection timing goes, you say you are using a factory map. --> The EGR gas itself was used for burn length control in that engine. You removed the gas flow, so now the engine is really touchy at its higher torque/output settings. The CM871 is not nearly as bad as the newer CM2250's and even worse, the CM2350's, but it is especially important to know that there are no factory maps designed to run higher torque output by the engine maker when there is no more EGR gas. You need all new custom injection timing, fueling, and other maps to keep everything safe under full non-egr control. Oil and coolant temps being higher than normal can be a heat transfer issue, but also can be from a bad fuel-air mix, or from cylinder temps being too high (too far advanced timing or too short of a burn length). That all goes back to programming most of the time. - Just some things to think about.

Personally, if I was faced with operating my engine at 80+% constant engine load capacity like you guys do down under, I would have disabled the EGR valve with it in a permanent open state, but used plates that had holes through them to allow for a limited/small amount of gas flow. At least some limited EGR flow will help a lot with keeping cylinder temps down and increasing burn length. This would definitely increase the life of the injectors, head, pistons, liners, etc. under such constant abuse and allow for better control of EGT's.

The whole combustion chamber and injection process was designed around that gas, and sure, most cases you can do away with it completely if you do the right things and re-program one carefully. Problem is that it starts to become a trade-off when the engine is going to be used at its upper limits under long term use. Sure the whole EGR valve and system sucks, it is a POS design from the factory, but it can also be used to maintain engine longevity under certain conditions high use too. I have seen it done before with great success on construction equipment that required a constant 90-100% torque output for extended periods of time. - Just something else to think about as an alternative of you can't get that thing under proper control.

Just some rambling thoughts on it while having my morning tea. Nothing too serious.

In any event, at 1650 rpm and high torque output, with no EGR gas any more, I wouls tend to think that your final injection timing should be around 5 degrees or so BTDC. Much more than about 6 or 7 degrees and it is in the danger zone for long term high output use. - I hear that AussieISX has done a lot of toying with this with engines that run in those conditions over there, we don't see engines being used the way you guys use them here in the states.


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250 kpa (36-psi) max on boost is ok and 500 C (930-F) on EGT's is ok too. Does not sound like you have it in any kind of immediate danger zones by those numbers, but you never know. Keeping oxygen levels a bit on the shy side like that is safer for the engines longevity.




My first thought is that something is getting the injectors too.

Just make sure there are no restrictions and everything has really good air and exhaust flow. Hopefully your exhaust is 100% open, cans are 100% hollow (or you have straight piped it). Any kind of exhaust restriction will get the injectors. Make sure you have really really good exhaust flow and that there are no obstructions of remnants of the old DPF system that can trap. reflect, or absorb heat.

Also, like AussieISX has said. Any kind of air in the fuel system will destroy them fast / cause overheating and other problems too.

Seems to be the first priority.

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These are just my own thoughts on it,.. I don't use a truck in the ways you guys over there do. After-all, I am full of S#it.