Brad Kirby

I have been having issues since I put the supercharger on the car.
2009 base, M6, A&A kit, Pat G remote tune.

I can sometimes push the start button and the car would take a good 10-15 seconds to respond and start. It didn't happen often, so I thought it must be the tune.

I stored it for winter and got it out about 6 weeks ago. Now it will hang the throttle at 3000 rpm until I bring the car to a complete stop. Sometimes it will just die and not restart until I turn it off, sometimes I have to sit a few minutes before it starts. Other time, it idles 300 rpm over commanded idle and it is rough. If it doesn't respond to a start command, my fuel gauge doesn't work, the service traction system message appears, and the security light stays on.

I notice on live data it will command the throttle open 20% until I stop. If it dies and let's me restart it right away (still coasting) I get the "engine drag control active" message, I have never seen that before yesterday. When the throttle hangs, it will pull itself about 60 mph in 6th. Sometimes the security light will stay on while I am driving but it never shows any other codes in the BCM or ECM.

I have codes,
ECM has U0073:00
BCM U2105:00
ABS has U100:00

Watching the bus monitor we can see it lose contact with the twisted pair bus wires that run to the diagnostic connector from the loop between the ECM, BCM, EBCM, and VCIM. I forget the name of that circuit, but it is the tan and tan/black wires, puns 6 and 14 at the DLC.

We replaced the BCM because it had corrosion, probably from a leak the previous owner repaired. I am taking the fender liner out now so I can check continuity between those loop wires at the ECM to the EBCM. I know one of the terminating resistors is in the BCM and the other in the ECM, but they pass through the EBCM. If the wires test good, my gut tells me the EBCM is the problem, but with the other resistor being in the ECM, it is also possible I need an ECM, but then I would have to buy credits again to tune it.

Has anyone had this issue or any more advice?

Brad Kirby

Both of the wires show 1.2.ohms from the ECM to the DLC.

C5 Diag

Pins 6 and 14 are Can Hi and Can Lo…with an ohm meter you should see about 60 ohms when checked between 6 and 14 with the battery disconnected….also you should see around 2.5 volts on either 6 or 14 with ignition in accy.

Brad Kirby

I have 60 ohms there. The monitor still shows the voltage drop at random, they don't both add up to 5 volts all the time. I wonder if it is getting jammed up in the ecbm.

C5 Diag

I don’t know what “monitor” you are referring to with this voltage drop ??…what voltages are you seeing ??

Brad Kirby

A friend of mine works at a dealership and brought his tech2 emulator home. It shows the voltage on 6 and 14. They mirror each other but don't always add up to 5 volts and sometimes shows an open circuit.

Brad Kirby

A new ECBM didn't fix the problem. I ordered a new ECM. If that doesn't fix it, any other suggestions?