Bad mpg and power 4.7mpg

[Trey7981]

To start, I've done the egr tune up. All filters and cummins had it on the dyno 2 months ago said it was good to go. I make 20-24psi 70% of the time on flat ground at 65mph. On grade boost is all over the place from 22-32psi depending on rpm. Cac has no leaks. And engine has lost all power and get 4.7mpg from tulsa, ok to minot, nd. Smooth idle no blowby u can see no burnt off oil or coolant. Oh and ultra sonic cleaning of doc, dpf, and scr. Any ideas where to look next

[hhow55]

I would replace the Exhaust pressure sensor, and the Intake pressure sensor next.

[Bengy88]

(01-06-2023 )hhow55 Wrote:  I would replace the Exhaust pressure sensor, and the Intake pressure sensor next.

Agreed. Especially if they have never been changed. Do you have insite? Are there any codes? The exhaust gas pressure sensor and imap sensors are both bad about getting soot loaded. You can not properly clean either of these and have a reliable sensor afterwards. Both of these sensors and the egr differential pressure sensor will cause your turbo to do erratic things.

[tree98]

(01-06-2023 )Trey7981 Wrote:  and ultra sonic cleaning of doc, dpf, and scr.

This is not a good idea at all. Any type of liquid cleaning of these components washes out the precious metals ruining the DPF and causing regen problems.

What does your aftertreatment history look like? What are your EGT's doing? Has the turbo actuator been off recently? If it was did it get calibrated with insite before it was re installed?

Have you done a turbo inspection to verify that the VG ring is moving its full travel? Is the commanded and actual movement of the VG close to the same while monitoring with insite?

Is the engine demandated? If it is you need to have Rawze look at the program because it's likely very bad and could be the cause of your whole problem.You didn't say what engine it is but if it's a 2250/2350 will it pass a rail leakdown test?

[Trey7981]

It engine say cm2350 dealer says epa10. It's all natural except for replaced accessories ie altenator, WP. So your saying DPF alternative aftertreatment cleaning system is bad? And the last time turbo, injectors where checked was September at cummins.

[Waterloo]

How many miles on the motor? And did you replace the two sensors, Intake and Exhaust back pressure?

[Trey7981]

I pulled the image sensor today and it was still clean also pulled the differential pressure sensor and it had a little carbon in it but not a build up.. but asking another question I notice my boost isn't going to full pressure when on a grade it was 22-24psi under full throttle and a 34k load going from Youngstown to akron. It did pull 28-30psi before. I'm going to have the turbo retested and see if the turbo or actuator is failing.

[Rawze]

(01-09-2023 )Trey7981 Wrote:  I pulled the image sensor today and it was still clean also pulled the differential pressure sensor and it had a little carbon in it but not a build up.. but asking another question I notice my boost isn't going to full pressure when on a grade it was 22-24psi under full throttle and a 34k load going from Youngstown to akron. It did pull 28-30psi before. I'm going to have the turbo retested and see if the turbo or actuator is failing.

A CM2350 should be about 36~ish or so psi if not de-mandated.. and de-0mandated, no more than 33 psi max on the boost. The numbers you are quoting are far too low.. even when you did think it was running ok.

[Bengy88]

Do you have a check engine light? Kinda sounds like you may be in a derate or the exhaust gas pressure sensor or imap sensor giving issues. Without a computer hooked to it to check some things it’s hard to say.