Cummins isx egt and possibly turbo issues

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Ram12vcummins

New member
Welll long story short

Truck got an inframe, mechanic poked hole in air to air. Diesel spec tuned and then removed an replaced with another also egr delete. Turbo hung up 3 times on a test at mechanics but with key on and truck running and then shutting off truck it reset back to what looked normal with no restriction.

Truck has high(in my mind) egt. Running down the road it’s around 800 empty and maybe 900 when pulling a load. If you get into it hard the egt will actually drop about 50 degrees which is wierd? So does this sound like symptoms of a bad vgt turbo? And should we replace the turbo with the like or go fixed vane and retune? Also is it best to just pay Cummins prices for the turbo? Truck also has a bit of a surging idle. So we suspect meter solenoid but not sure how to test and I think they are $750 a pice? And do the timing solenoids need to be changed as well? Thanks
 
Ram12vcummins said:
Welll long story short

Truck got an inframe, mechanic poked hole in air to air. Diesel spec tuned and then removed an replaced with another also egr delete. Turbo hung up 3 times on a test at mechanics but with key on and truck running and then shutting off truck it reset back to what looked normal with no restriction.

Truck has high(in my mind) egt. Running down the road it’s around 800 empty and maybe 900 when pulling a load. If you get into it hard the egt will actually drop about 50 degrees which is wierd? So does this sound like symptoms of a bad vgt turbo? And should we replace the turbo with the like or go fixed vane and retune? Also is it best to just pay Cummins prices for the turbo? Truck also has a bit of a surging idle. So we suspect meter solenoid but not sure how to test and I think they are $750 a pice? And do the timing solenoids need to be changed as well? Thanks
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How many miles on turbo and metering/timing actuators?
 
jfaulkner said:
How many miles on turbo and metering/timing actuators?
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No clue. Truck itself has 1.48 mil km. Dads had the truck for a year I would say. But high egt issues haven’t been a problem until inframe/egr delete. The egr delete could have just made a bad turbo more noticeable as the exhaust has only has one place to go now.
 
I suspect it's the tuning, both surging idle and EGT dropping under load are symptons of bad tuning.
 
Where is the pyro probe mounted? Manifold or after the turbo in the exhaust pipe?
 
Probe is mounted post turbo. Cm870. Changed actuators last night and it’s running better. Egt still at 850-900 but runs better so will see what it does behind a load. Should be grossed out around 110,000lbs. No one can tell me if those are high numbers for that motor but I assume they are higher than they should be by 150-200 degrees with light pulling.

The vgt still operates and boost is smooth on and off.
 
A good dyno tuned tune for mpg with a vgt will have higher than usual EGTs. How much? You have to ask the tuner.
 
He just phoned me and loaded he can’t get over 30 psi boost. Expensive test but might just have to swap the turbo out. See if that’s the problem.
 
Ram12vcummins said:
Probe is mounted post turbo. Cm870. Changed actuators last night and it’s running better. Egt still at 850-900 but runs better so will see what it does behind a load. Should be grossed out around 110,000lbs. No one can tell me if those are high numbers for that motor but I assume they are higher than they should be by 150-200 degrees with light pulling.

The vgt still operates and boost is smooth on and off.
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I would say you're right that it's running hot with the probe post turbo.
 
Charge air cooler isn't the only thing in that system. There are numerous boots and the infamous intake manifold v-band that regularly cracks on those as well.
 
Couple of boots had a bit of outside wear. But no holes. Those will be replaced right away as well. Will look closer at the intake.
 
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This is why i asked about the boost, I had a cm870 after a head install that had crazy egts, narrow powerband and low boost. pressure tested cooler, tested boots vice grips on turbo actuator, timing on cams...ect drove me nuts. turns out the guys who put the head on used the ecm shoulder bolts in the ecm cooling plate and it was tight but wouldnt hold more them 25# of boost. The bolts topped out before sealing the plate to the head. Honest mistake but they walked away from it.... worth a look
 
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