CM870 turbo issue
09-10-2021, (Subject: CM870 turbo issue ) 
Post: #1
CM870 turbo issue
Hi, everyone. I'm having a problem with my turbo, can't figure out what is it. It's a 07 Volvo with CM870, demandated.
At first when you accelerating or driving uphill, my turbo pressure gauge starting to fluctuate. This video shows exactly what happens
I checked the codes and this one popped up: Turbo Speed, Value too low, active, MID 128 PID 103 FMI 1
After a couple of days it become worse. At some point the pressure won't go more than 15PSI, but the fuel data at the moment shows around 4.9MPG with full throttle (which usually is 2.5-3.0)
Then, somehow it goes back to fluctuating mode with the pressure goes up as much as 35PSI. And then, after some time - again to 15 with power loss but increased fuel mileage.
On top of that - another code pops up: System diagnostic code #1, Electrical fault, number of events 39. MID 128 SID 151 FMI 3.

Turbo is less than 1 year old and still under warranty. Anyone have any idea what is happening?
09-10-2021, (Subject: CM870 turbo issue ) 
Post: #2
RE: CM870 turbo issue
What you describe sounds a lot like the all too familiar CM870 boost spike and fall back problem.

Most of the time it is caused by bad delete programming on them (assuming there is nothing wrong with the turbo or controller).

who did the de-mandate programming?... and when ... this is the bigger concern, as bad delete programming will cause exactly what your describing.

Pull a copy of the de-mandate program out of the ecm and e-mail it to me for review. At least you can see if someone did an ok job or not.

It can also be the air operated VG controller or the turbo arm itself hanging up. Turbo and controller inspections need to be done to ensure this is not a big part of the problem too.

User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
09-11-2021, (Subject: CM870 turbo issue ) 
Post: #3
RE: CM870 turbo issue
If its deleted then yes 1st stop is having the programming checked. Can't go any further diagnosticly till you know the programming is correct.

If it a stock calibration with the EGR still intact and operational, then you need to do a full EGR tune up to be sure everything is working as it should in the system. Then you'll need to monitor if the ECM is derating (using Insite) and fix whatever its showing is causing the intermittent debate. if none of those are going wrong then you'll have to test and check the VG air actuator circuit for leaks. Even the most minute leak will mess with this air circuit. It need to be completely sealed and zero kinks anywhere. Insite has an on/off test that will allow you to check for leaks. If all that looks good then you'll probably be looking at a faulty VGT actuator {air} control module. There is no easy or good or cheap way to test them except swapping it with a known good one. If it needs replaced spend the money and buy ONLY a new OEM Holset control module the rest are junk at best. I know from a lot of past experience.
 Thanks given by: Rawze
09-13-2021, (Subject: CM870 turbo issue ) 
Post: #4
RE: CM870 turbo issue
It was demandated about 1,5 years ago.

Thank you guys! I will try to pull up the copy of the software. Will keep this updated.

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