Air control valve

[Benjamin9669]

Does anybody have any input on these junk turbo air control boxes ? Keeps throwing code for 2385. The front cover was leaking oil down on it and got that all cleaned up, now it’s acting even worse turbo spooling up and down throwing a check engine light. Connections are good and cleaned. Egt climbs when it acts up. Seems to have a rough idle and intermittently loses 3rd stage Jake.

[Rawze]

They aren't junk. At least not the OEM ones any ways.

The turbo control valve on the CM870's do go bad after several years, they usually last about 6-8 years on an otherwise healthy engine.

They also start acting up if your air system is not pristine. Dirty air / moisture, etc. or poor pressure regulation, etc. running thru them eventually gets to them, causing them to act up or go bad.

CM870's have always been wonky with the turbo. That is why they went away from that design and went to electronic control.

Things have to be just right for them to run and run well... including the air supply, the actuator, the turbo mechanism itself .. and don't forget about the programming. Bad delete programming is a plague for those engines and this alone can make one start acting funny all of the sudden too.

Everything from the air pressures to the electronics to the ecm and the mechanical components has to be in good shape for them to operate like they are supposed to.

the engine is also supposed to have 36-38 PSI sustained boost while in a hard pull too. Any silent derates in the ecm (a common derate/symptom of unplugging the egr or a using bad delete program) and it will typically spike and then will fall back to 32-psi or less.

[Matrix2613]

Not to hijack this thread, but my air control actuator is bad and the 3770742 part number does not exist on the shelf and there is no available date for a replacement. Is there a way to put {maybe}, a newer electronic turbo and have it work with the cm870 ecm? This Truck has been down for 7 months waiting on this piece

[tree98]

You can convert an 870(air actuator) to an 871(electronic actuator) you'll need a new turbo with the electronic actuator and an 871 ECM, wiring harness, Oh and don't forget a custom program to make it all work.

If I were you I would spend a day calling cummins distributors around the country and try to locate that control box. I would bet someone has one.

[Rawze]

There have been quite a few people who have converted their 870's to 871 VGT controller. I think forum member 'running rough' even did it. Maybe get in touch with him?.