ISX 2350 485

[Rawze]

(01-31-2017 )zare6 Wrote:  Hi anybody experiencing declining fuel economy with this engine? I have 200000 miles on it, boost goes to 38 psi runs great dynoed at 440 hp at the wheels, dpf filters are clean, started off at over 7 mpg now I'm down to 5.

A CM2350 has a higher compression ratio than older model engines. That engine can make 700+ HP with only 32-33 lbs of boost. It should be peaking about 32-lbs of boost or so max from factory.

I have test driven many that were factory stock, and it is not normal to have 38. - It is simply too high and it is over-boosting. This alone will make your fuel mileage and engine efficiency suffer/significantly lower. It will also set the engine up for more severe problems like detonation, liner issues, and a cracked head.

Perhaps someone put the wrong (or a bad) program in the ECM? -- OR perhaps you have some sensors reading incorrectly that is causing it.

Start with a thorough EGR tune-up, replace all the EGR sensors, etc. and find out why it is over-boosting.

Also check to ensure your Doser injector is not leaking.

Check that your decomp. tube is not partially clogged. -> http://rawze.com/forums/showthread.php?t...07#pid1807

Also, you should perform an injector leak test...
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