ISX 2350 485

[zare6]

(02-01-2017 )Rawze Wrote:  

(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...

Hi thanks, the egr has been checked out, cummins had this engine on the dyno after they replaced the liners due to excessive oil consumption and they know what the boost is at, its been like that right from the first day I drove it. Ill look into the doser injector,