2015 Freightliner M2 106 8.3 Cummins Check Engine Lights ON....

What condition(s) would cause BOTH CEL's to come on first run of the day and then go out after about 10 minutes of driving ?

The truck appears to be running ok.... other than low power on take off and lower RPM's. (Turbo issue ??)

Yes, the truck will be going into the shop soon to get checked out.

I'm just curious as to what the causes may be and trying to educate myself.

TIA

 

If we are just quessing id check coolant level.

Once the truck warms coolant expands and comes up above the sensor.

Otherwise you need to get hooked up.

 

Yes, Coolant level is good. I check it every Pre-Trip.

BTW, I "think" the engine maybe a ISL9.... 8.9L. Not sure....

The engine power (to me) seems very low down below 1800 RPMs or so. I know the turbo kicks in around then, but the truck can hardly get out of it's own way before that.

What would cause low power down in the lower RPMs ?

The Allison transmission also shifts UP to next gear WAY too early IMHO. Especially with a real heavy load. Is this normal ?

 

BUMP..... for questions in above posting.....

 

Look into your CEL first. This may fix your low power concern.

In addition I would pull the intake and clean the EGR and delta sensor crossdrillings very well.

DPF service due? Overhead set?



You have a manual shift mode if you need it. That trans will pick the best gear for fuel most times, so shifting early is kind of normal.

Have the adaptive shift reset with DOC. Then drive like you normally do to see if it helps shift more to your liking.

 

Fortunatley for you, I was up in God's country with no internet or phone.

Against orders, sue me. Momma and kids needed some time away from the house...

 

Employer finally got the truck into the shop last week.

Turns out the turbo wastegate actuator was bad. The shop replaced it and now the truck has good power once again. Still has no balls under 1800 RPMs. I guess this is normal before the turbo kicks in. ??

The transmission stills shifts very early IMHO. The 2-3 shift is super quick as is the 3-4. It shifts right around 1700 RPMs or so, just as the engine is starting to get into the power band. 1800-2300 RPMs.

This is VERY problematic while carry heavy loads ! The truck has a very hard time getting up to speed.

What can cause this in the Allison transmission ?

 

The combo you have is sluggish at best in a tandem and will never feel like a real powerhouse.

Your peak torque is low, around 1300. Horsepower and torque both drop off rapidly above 2100.

Did you get hooked up and try resetting the shift adapt?

 

I don't know what the rear gears are but that could be a big part of the problem. I'm guess they're pretty low gears. Runs like a freight train going 70-75 MPH. It's governed at 75 MPH. Just has no real power down low. RPMs and Speed.

I reported to the shop about the early shifting issue. I don't think they knew or had the capability to check it out.

I did toy around abit with the manual up/down shift button and MODE switch. The truck responded pretty well when the engine was allowed to get up to 2300 RPMs or so. Just wish it would do it when I need it too.... ALL the time.

How does one reset the shift adapt ??

 

You must connect with Allison DOC program to perform the reset.