P0106 E38 service StabiliTrak

I am experiencing an issue with StabilitTrak that I have never seen before, hopefully someone can shed some light on this.

The car is a 2014 Z28, E38 ECU, LS7 engine, had cam and headers when I got it. I did some very basic tune changes and the car ran night and day better with basic idle adjustments. I drove the car for about 3000 miles with no SES light or any StabiliTrak issues. One random day in stop and go traffic the service stabilitrak light came on while sitting still. As soon as i started rolling the light went off. This kept up for a few cycles then I got a SES light and the service stabilitrak light stayed on.

Got home and read DTCs, only DTC was P0106. I cleared the code, drove and all seemed well. As soon as i killed the car and restarted it, P0106 came back. It may be a coincidence, but this was the first cool day we had since I got the car. We have had several 90+ days since and I tested this and still had issues.

Now, to the real issue. I know how to completely disable this P0106 test, but it appears to also disable traction control and stability management when I do so. I do not get a "Service StabiliTrak" light, but traction control does not function at all when I disable the P0101, P0106, P0121 using the coolant temp parameters. I dont have a way to test this because if i enable the P0106 test, I immediately get P0106 and that disables StabiliTrak but also generates a "Service StabiliTrak" Light. It is very possible that it is a hardware or wiring issue but I have tested all grounds to ECU and body control unit. MAP reading was around 65KPA at idle, Im not sure what range the P0106 is looking for, but idle vacuum has been the same from day one and this is a new issue.

My questions are:

1) I also have repeatedly got lots of communication DTCs that dont even show up with HP-Tuners, I believe you need a Tech 2 or equivalent to read them because that is what I borrowed. These all seem to be set any time I flash the ECU using HP. Is this a common issue?

2) The gen3 ECUs had tables to set the MIN and MAX acceptable values for P0106 test results. This appears to be gone on the gen4 stuff. Is there something I am missing? Can we still change the acceptable MAP range for P0106?

3) Has anyone seen similar issues with ZL1 or Z28? as far as i know, these two models are the only ones that have the more advanced StabiliTrak system.

4) Does anyone know if the body control unit waits on a successful P0101, P0106, and P0121 before enabling traction control and stability management? If so, disabling these tests could cause this?

Thanks, I would appreciate any input on this issue.

That's an odd issue. Just a couple of questions for you...
Does the MAP sensor seem to read correctly?
Does the BARO reading display correctly?

To answer your questions...
1. HP Tuners will only read the ECM/TCM/FPCM trouble codes. Since your vehicle is a manual trans application, you'll only read the ECM/FPCM DTC's. Any other computer codes...such as BCM will have to be read by other means.
2. Those aren't available yet in the GEN 4 PCMs. However, you can disable the High/Low voltage MAP sensor tests independently.
3. I haven't seen those issues.
4. I'm not sure if that's the case or not.

I will log some data today and make sure, but I know the MAP appears to be functioning correctly, and I replaced it with a OEM AC Delco unit just to be sure. Same issue with both sensors.

I dont even know where the BARO Sensor is on these cars.

Laptop was dead so I didnt get any data logs, but I discovered that traction control seems to work in the competitive modes. Does not even try to work in normal mode.

Really strange issue and Im starting to lean towards wiring or BCM issue. I guess since it seems to work ok in competitive mode then the issue is kind of resolved but it will still bother me if I dont find the root cause.

I think disabling a pretty basic fault code like P0106 is not a great idea. Also, that the problem did not appear until you'd put 3000 miles on the car using your calibration has me thinking your cal has little to do with these fault codes setting. My wild-assed guess is there's a problem in the wiring harness somewhere.

First, I'd re-enable that DTC. You already know the problem is not the sensor. In fact, most DTCs are caused by faulty wires and connections rather than sensors or actuators. Since you have a new sensor which did not affect the problem, look at the wiring and connections. You need a Factory Service Manual for its repair procedures for P0106 which will enable you to trace down a problem with wires and connections related to the MAP sensor.

After you solve that code, if the service stability enhancement light still comes on, then you need a scanner, like that T2 you borrowed, which supports the car's chassis computer and can read whatever "C codes" are set in the EBCM along with the FSM to solve those codes.

Lastly, all those U-codes tells me various modules have lost communication with each other. If you clear codes and the P0106, the SES codes and any of the U-codes reset, it would seem obvious that there is a wiring/connections problem somewhere as U codes are setting because modules cannot communicate. Bad wiring or connections would cause modules to loose communication with each other.

Thanks for the input. I agree that its likely wiring issue but I have checked all ground locations listed in the service manual and checked grounds from ECM and BCM connectors with power probe and all check good.

Do you know if it is normal to get communication codes after flashing ECU with HP Tuners on these vehicles? I can clear them with T2 and they don't come back until the next time i flash then they immediately come back. I dont want to go down that rabbit hole if this is normal.

What version HP Tuners are you using?
I recall having an earlier version that set U codes on some of the E38 applications and I had one BCM that wouldn't "wake up" after a flash. HP Tuners issued a critical update and resolved the issue pretty quickly.
Thanks,
Kevin

I have version 4.0.12

I tested the MAP and MAF circuits last night per the service manual instructions and all seems in line other than the manifold pressure at idle. The service manual says that P0106 will be set if not between 25-52 kpa at idle. Mine is definitely outside that range but I went back to old data logs and it appears to have been at least 60 kpa from day one.

I have searched for vacuum leaks and have not found any. I even bypassed PCV to rule that out, the only thing left is EVAP system. I have all the DTCs turned off for EVAP so maybe something has malfunctioned there.