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ISM Cummins boost problems???????????????????
I have an ISM Cummins (11 liter) that has erratic boost pressure.
It will only build 10psi until 1400 rpm then will usually go to 30-35 psi. However it sometimes will not hold a steady psi , it jumps about 5psi.
you can feel the engine surging. Some time it will hold steady for a long time/hill.
EGT's max at 720 where it used to max at 940 , I know it's not getting the fuel it used to.
When pulling down under a load , as soon as it hits 1400 rpm , boost will fall to 10 psi again.
Also only 10 psi boost until temp is 180 degrees , Cummins says that is NOT part of the ECM program
Cummins can't seem to figure out the problem, doesn't throw a code on the ECM.
I have changed the filter several times , the turbo was starting to throw some oil , new one, they were SURE that was the problem. Checked the inter cooler for leaks , air filter is pretty clean , they were also SURE that was the problem, until I took them for a test ride with it removed.
I'm pretty sure it's in the ECM that's de rating the fuel for some reason , just can't figure out why it won't throw a code IF that's the problem.
They want to put a TEST ECM on then change it to a new one if that fixes it , I say try the new one first to save me the labor.