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+--- Thread: ISX15 low power after turbo replacment (/showthread.php?tid=10369)
ISX15 low power after turbo replacment - jpaisley81 - 10-25-2025
Hi everyone, first post here. I replaced the turbo and actuator on an ISX15 2350 (525hp, 1850 tq) with cummins parts. I also resealed the exh manifold. The truck seems to make less boost and percieved power than before when pulling a load. Boost is down 5-6psi compared to the previous turbo. The previous turbo did not fail completly, the inlet housing ring came loose and began to strike the compressor blade. Runs great bobtail. No codes.
I have made log files from 2 similar trucks, same engines and ratings. The uderpowered truck appears to make less boost and has much greater EGR flow than a companion truck. I have 2 logs attached, filtered by max throttle. My pressure units are set to PSI.
Is it possible to have the VGT installed 1 tooth off and still calibrate sucessfully? If so, could this be a source of the issue? Is it possible cummins provided the wrong or defective turbocharger? PNs are verified with cummins.
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RE: ISX15 low power after turbo replacment - Rawze - 10-25-2025
Do a full EGR tune-up on it and see if some of the power comes back.
info: https://rawze.com/forums/showthread.php?tid=842&pid=7030#pid7030
After that, monitor the engine with the CT software and see what is in control of the 'CBL_Fuel_state' during a hard pull or when you think its holding power back, and the code(s) it shows will tell you exactly why.
info: https://rawze.com/forums/showthread.php?tid=3317&pid=28636#pid28636
RE: ISX15 low power after turbo replacment - jpaisley81 - 10-25-2025
Thank you, I will collect that information and report back. It may take a few days before I can get hooked back up to this truck.