2017 ram 2500 6.7 cummins. 79k miles. Truck is fully deleted (EGR/DPF/exhaust). Adult driven. Problem started very suddenly. Truck has never had any issues I've owned it and maintained it since brand new. No check engine light or codes, no exhaust smoke at all (usually dumps some black smoke upon heavy acceleration and my tune), no rough start or idle, exhaust brake is working as it should, fuel rail pressure is meeting demand (idle around 4600 PSI / WOT is getting about 20,000 PSI). From my research it should be getting some more fuel pressure at WOT. Boost is only reaching 21 PSI at WOT which is lower than normal for the truck also. Truck has no power very very sluggish. Low speeds feels ok..if you don't get on it and will get to highway speeds... eventually. Made sure all Intercooler boots and the whole intake/turbo system is sealed well and not having a major boost leak. S&B intake Air filter is clean, MAF sensor looks to be clean and good. Both mopar fuel filters recently changed have 675 miles/45 gallons through them/ also tried both brand new Napa filters with no change. I ordered a new fuel rail pressure relief valve to see if that solves anything. Also have a boost leak kit on the way to attach at the turbo and pressurize the system to make sure I didn't miss any possible leaks. It seems to me like a fuel or boost issue but everything I have tried so far has had no improvement. Any other ideas?

 

Are there any codes???

 

It sounds like you've already checked a lot of things that could cause low power on your 6.7 Cummins. Since there’s no check engine light or codes, and you’ve ruled out obvious issues like boost leaks and dirty filters, here are a few other things to consider:

Fuel System: You’re right that fuel pressure at WOT seems a bit low. Since you’re replacing the pressure relief valve, that could help if it’s losing pressure. You may also want to check the fuel pressure sensor or even the lift pump if it’s not delivering enough fuel.

Turbo: If boost is low, the issue could be with the turbo actuator or vanes sticking. You’ve already checked for leaks, but a faulty actuator could also cause low boost.

Tuning: Sometimes a problem with the tune can affect fuel and boost levels. If possible, reload or update your tune to see if that helps.

Exhaust Backpressure: Even though the exhaust is deleted, there could still be a restriction somewhere. You might want to inspect the whole exhaust system to ensure nothing is blocked.

If none of these solve it, you could try data logging to monitor more detailed parameters during driving. That might help you pinpoint the issue.