Turbocharger?

[Ravenwood]

I now have a new issue with my CM2350 and I’m thinking it might be the vanes are hanging up. If you’re familiar with my past issues a lot of coolant was pushed through this turbo this spring.
Whenever my engine brake engages whether manually or on cruise. The VGT tries to do something but extremely weak. If I cycle the switch down to 1 and back to 3 then it will work. If I give it fuel to downshift it will stay but any power whatsoever and I have to cycle the switch again.

Also if I’m on a really hard pull with a step in it that brings my rpm’s up to about 1900 until the next step up. The engine will start to shake, black smoke, no power (feels like it’s going to fuel knock) until I let off completely and let the engine brake bring my rpm’s down to idle and quickly grab whatever gear I can before I stop moving. (this only seems to happen if I let my rpm’s climb up passed 1700)
I did the actuator tests and it passes. No codes on Insite.

Any advice, answers or suggestions would be greatly appreciated
Thanks in advance.

[Rawze]

monitor your boost pressures when its acting up, etc.

[Ravenwood]

On the fuel I’m around 38 psi, smokes like a 425 Cat when I stomp the throttle, it lags like it’s running a non VGT turbo. That’s when it’s running good!
When it acts up around 30 psi, the air cleaners howl you can hardly see the back of my trailer with the smoke. If I hit 1700 it will maybe act up, if I bring it up to 1900 it probably will. Only under full power, if it’s running 1/2 power it’ll do 2100 without any issues.

On the engine brake max I’ve seen is 20 psi, once I cycle the switch 30-35 psi and it’s consistent. It doesn’t work right unless I cycle the switch.

Fuel use is garbage again. Since the last update the NavPlus says 7.1 mpg but it’s 2 mpg at best.

[Rawze]

almost sounds like bad linkage between turbo and actuator.

[Ravenwood]

I guess I’m looking at a new turbo then!
Would a HE561VE work since I have one or will that be a another headache?

[Rawze]

(07-28-2025 )Ravenwood Wrote:  I guess I’m looking at a new turbo then!
Would a HE561VE work since I have one or will that be a another headache?

is that a VGT? .. if not then ...

On ISX's that came with VGT turbo, the ecm uses that VGT to control the proper fuel-air-mix, keeping internal friction down. The ECM controls the 'Air' ... not the 'Fuel' to achieve the proper mix.

Putting a manual turbo on a modern ISX that was not meant for it will cut its engine life in half or less due to excessive friction and other issues associated with improper fuel-air-mix issues.

It also negatively effects fuel mileage, often greatly, the engine is gutless at lower rpm's, and the engine brake goes away.

I.E.> it is NOT A GOOD IDEA AT ALL!, and anyone who would tell you otherwise is a complete fool.

--------------

And if it is a VGT,.. according to that model number, it is a 500-sderies turbo. You will loose about 1+ mpg across the board by putting a 500-series turbo onto a CM2350, as it is much bigger and harder to spool up than the 400-series that come with CM2350's.

[Rawze]

(07-28-2025 )Ravenwood Wrote:  I guess I’m looking at a new turbo then!

you need to do proper turbo inspections...
ref: https://rawze.com/forums/showthread.php?...18#pid1618

[Ravenwood]

Turbo looks good, actuator passes, hyst. Test passed, IMAP sensor voltage is good, sensor reads as it’s should, charge air system has been pressure tested and passed.
Only thing I haven’t done is remove it and see if it’s dirty. The intake manifold is clean as a whistle so I don’t think the sensor would be dirty.
I haven’t checked the line from the exhaust manifold to the back pressure sensor.
Made a trip and it did it again at lower rpms.
I did notice that the intake manifold pressure data valid but below normal range-least severe level code 6864 came back and that seems to be the cause as far as I can tell. Runs fine before
I’m just about ready to try the old engine killing file back in to see if it happens with it.

[Ravenwood]

(07-29-2025 )Rawze Wrote:  

(07-28-2025 )Ravenwood Wrote:  I guess I’m looking at a new turbo then!
Would a HE561VE work since I have one or will that be a another headache?

On ISX's that came with VGT turbo, the ecm uses that VGT to control the proper fuel-air-mix, keeping internal friction down. The ECM controls the 'Air' ... not the 'Fuel' to achieve the proper mix.

Putting a manual turbo on a modern ISX that was not meant for it will cut its engine life in half or less due to excessive friction and other issues associated with improper fuel-air-mix issues.

It also negatively effects fuel mileage, often greatly, the engine is gutless at lower rpm's, and the engine brake goes away.

I.E.> it is NOT A GOOD IDEA AT ALL!, and anyone who would tell you otherwise is a complete fool.

Thanks I thought it was an VGT for an 871? I inherited it so I figured I’d ask. It‘ll be returned to the odd parts pile.