CM870 Boost issues

[Hemiterry]

I’ve been struggling with erratic boost issues on my 2006 International 5600i tandem dump with a 400HP CM870.I’ve replaced air intake and temperature sensors, exhaust pressure sensor, EGR temp sensor, new muffler, air filter, checked turbo actuator travel and my ECM flashed by International to my VIN. I continuously get codes for intake pressure and temperature. I finally crossed my fingers and spent $1300 on a new turbo controller and it fixed everything! I’ve never had over 32psi of boost until after I replaced the controller and got 38! For the last week the truck ran incredible and didn’t throw any codes. Unfortunately today I was pulling out unloaded onto the highway and I suddenly lost boost again and I’m right back to where I started. The turbo shoots up to about 30psi then falls almost to 0 and then slowly winds up back up to 30 but when I start up a slight hill it tops out at about 20psi. Obviously the turbo controller fixed it for a short period of time but I can’t just buy another one without knowing if or why this new one suddenly stopped working.

[Rawze]

was it an OEM unit?.

And has anyone ensures that the air supply to it is properly regulated and not leaking?.

[Hemiterry]

It’s a genuine Holset and I have it regulated at 90psi.

[Hemiterry]

I have checked for leaks and didn’t find any. Could it be my supply air could be dirty or wet and ruined the controller?

[tree98]

(11-05-2023 )Hemiterry Wrote:  It’s a genuine Holset and I have it regulated at 90psi.

You bought it from a licensed Cummins distributor?

[Hemiterry]

I purchased it on EBay from a reputable seller but I can’t say if they’re a licensed distributor.

[tree98]

I hate to say it but there's no way to know if what you have is a legit part. Parts that are bought anywhere but at a licensed dealer are a crap shoot, especially online places like eBay.

You end up in this exact situation, having problems and trouble figuring it out because you've already changed a particular part so you move on to look for other causes, yet the problem is the aftermarket/rebuilt/ Chinese knock off part you changed that looks exactly the same as the genuine part.

In other words you just don't know exactly what your getting. Here's a great example of this.

https://rawze.com/forums/showthread.php?tid=9128

Unfortunately the only way to rule it out as the cause is to buy one from a dealer. I'm betting it fixes your problem.

[Hemiterry]

Yea I’m officially done with online parts. This thing looks legit but I know they’re really good at making fakes these days. I’m gonna look the truck over one more time in the morning and unless I find a problem I guess I’ll call and get one from Cummins. My truck doesn’t have any kind of filter in line before the controller and I was thinking of adding one to eliminate any contaminates that could possibly damage it.

[Rawze]

(11-05-2023 )Hemiterry Wrote:  Yea I’m officially done with online parts. This thing looks legit but I know they’re really good at making fakes these days. I’m gonna look the truck over one more time in the morning and unless I find a problem I guess I’ll call and get one from Cummins. My truck doesn’t have any kind of filter in line before the controller and I was thinking of adding one to eliminate any contaminates that could possibly damage it.

some trucks did have a screen filter in the air line before the controller. They were also known to clog up and make problems.. so if you install one, make sure you service it regularly.

Also if your engine fan is leaking while engaged (or other air circuits) it can cause the turbo controller to act up. - Start up the truck, let it build air all the way up until the dryer blows off (above 120-psi) and shut key off, but turn key back on as soon as engine stops turning to keep everything alive, then jump out to find any air leaks that are only occurring with key on and air above 120-psi.