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Rawze · 07-19-2023, **(Subject: Cm2250 derate )**

(07-19-2023 )Aleeex Wrote: I could not get CT set up…

But in insite I did manage to catch it say “air fuel control derate” under acceleration

Inactive code appeared. Turbo inlet air temp sensor

An 'air fuel control derate' is quite normal normal if you try to accelerate hard, until the turbo catches up to the engine. It is called turbo lag and is normal. It should however not be a sustained condition though, and holding the engine back after the thing catches up to itself.

What is the turbo getting to in boost?. What is the turbo RPM's as well as boost levels when it is being held back?. if the turbo is spinning its arsse off and there is low boost then it is a mechanical issue making lower then normal boost. Blocked exhaust, blocked intake, CAC boot loosing air, CAC leaking too much, or the turbo itself could have damaged turbine blades.. or in some cases.. could be the turbo was built wrong like this guy suffered thru:
ref: http://rawze.com/forums/showthread.php?t...8#pid76838

BTW: You did not mention what the make/model truck this is. Some trucks need different turbo settings to make them have proper boost.

Aleeex · 07-20-2023, **(Subject: Cm2250 derate )**

This is a 2012 Pete 386.

The boost varied on this drive. The lowest was 25, highest 31

At 31 psi I believe the turbo speed was around 120k

This tune you had set as a square nose Pete because I was seeing 41psi.

I think I managed to get a log in ct. I don’t have the knowledge of how to review it. Is that something you can look at?

Aleeex · 07-20-2023, **(Subject: Cm2250 derate )**

My turbo was replaced aug 2022. Cummins reman (purchased from Cummins)

Rawze · 07-20-2023, **(Subject: Cm2250 derate )**

(07-20-2023 )Aleeex Wrote: My turbo was replaced aug 2022. Cummins reman (purchased from Cummins)

Is there a thick block plate between the exhaust manifold and the EGR cooler?. If not, then chunks of carbon buildup could have come loose and gone thru the turbo, damaging its exhaust blades.

Something caused that boost to drop off like that.

As far as CT goes, record the desktop with some generic desktop recording software while you have the settings you want to record showing.

Aleeex · 07-20-2023, **(Subject: Cm2250 derate )**

Egr cooler blocked off

Rawze · 07-20-2023, **(Subject: Cm2250 derate )**

(07-20-2023 )Aleeex Wrote: Egr cooler blocked off

You could try replacing the turbo speed sensor? The. 120k+ rpm seems a bit on the high side for only 30 lbs boost, but not totally out of the ballpark. Still points towards a boost leak or slightly damaged exhaust turbine blades (some debris or carbon buildup chunk thing went thru them).