2009 Pontiac L76, Non DOD, all other parts LS3.

[BobiNHSV]

Using original E38 ECU and Trans T43. Operating System 1250228. Reprogrammed to remove VATS and delete monitoring un needed DTC's. New Harness and programming by BP Automotive. Engine on test stand. Fully charged battery, Ignition Switched from TS Control panel. Power to IGN wire in Harness. Starter Switch press to start direct to Starter Solenoid. All wire harness items needed attached. Function verified on IGN, START, FUEL PUMP, Cooling Fans, Trans cable attached to trans (on separate stand). Original problem was no fire or fuel. Traced to miss-wire on CMP sensor, signal A and C reversed. Engine now fires, runs for about 2,3 seconds and shuts down. No throttle response (throttle operation verified) After starting won't start again unless it sits for some time before the next try. Sounds like classic VATS problem. VATS is disabled in both positions in SW. I can't find anything in the SW that points to a program problem.

Anyone have any ideas?2009 Pontiac G8 E38 BP Tune.hpt

[5FDP]

Was a write entire done with the VATS removal?

Did you check for any VATS dtc's that need to be set to no error reported??

[BobiNHSV]

Everything is No Error Reported. I have attached the ECM File to the post so anyone can have a shot at finding the obvious fault. I have read until my eyes are crossed.

[blindsquirrel]

Which ECM pins are getting B+/IGN? There is a sneaky one on E38s that's labeled as something like 'data communications' in the diagrams, but if you follow it over it's actually a switched IGN feed.

[blindsquirrel]

X1 pin 18.

E38 X1-18 1of2.png

E38 X1-18 2of2.png

[BobiNHSV]

On the way to the shop now. I will verify this line. I have found one error in the harness already.

[BobiNHSV]

Checked. Voltage is there. Engine fired immediately, ran for 2 seconds, then shut down. No restart. Waited 2 hours, then tried again. Engine is totally flooded. Tried flood clear procedure with throttle at 100%, No help. Seemed to get worse.

[blindsquirrel]

Are there any DTCs at all? There are some throttle faults that will cause fuel/spark to be shut off for safety, your mention of throttle being disabled after it faults out could be pointing to something. Or, it could be an internal ECM problem that just looks like a ETC-fault shutdown. Is this the correct stock GM throttle body?

As a sanity check I would do a new read of the tune, save as new filename, and do a compare to the file you last wrote to it to make sure everything matches.

[BobiNHSV]

Yes, it is the stock throttle body. I am going to try to get a short scan to see if anything stands out. I have never written to the ECM. Was reprogrammed by BP Automotive. I have not seen any DTYC's, but will look closer. Thanks for the help.

[blindsquirrel]

The file you supplied, did you read that out from the ECM yourself or was it supplied by BP? Just trying to make sure that the file we're all checking is the same as the one in the ECM right now.

Saved logs will show any DTCs, down at the bottom of the Channel list pane there's a tab, 'Details', that shows controller info and codes. There is also a separate toolbar botton up at the top to do a more conventional code reading.

[BobiNHSV]

Thanks for your help, the file is as read from the ECM/TCM. If a write entire wasn't done would it appear as VATS disabled in the program? BP is closed now but I will ask tomorrow. This really seems like a VATS problem. I scanned a start try today and I only got about 3 seconds of data. G8_Log1.hpl (388.4 KB)

[blindsquirrel]

ECM
P0641 - Sensor Reference Voltage A Circuit/Open (Current)
P0700 - Transmission Control System (MIL Request) (Current)

TCM
U0100 - Lost Communication With ECM/PCM A (Current)

[blindsquirrel]

The service manual uses different language for the P0641, the actual is 'P0641: 5V Reference Circuit 1 Malfunction'. If that 5v line is out of spec for more than 1/2 second the code sets. Probably, ECM is seeing the loss of APP Sensor 2 as a fault that qualifies as an engine-off-for-safety situation. I would contact the harness people with these codes.

2009 G8 5vref.png

[goodwrenchdave]

Try unpluging your gas pedal and try to start. What pedal are you using. The 2 app circuits are reversed on some pedals. Referance 1 feeds 5volts to :
•The manifold absolute pressure (MAP) sensor.
•The fuel tank pressure (FTP) sensor
•The air conditioning (A/C) refrigerant pressure sensor.
•The accelerator pedal position (APP) sensor 2.
•The engine oil pressure (EOP) sensor.
•The camshaft position (CMP) sensor.

something is disrupting your 5V reference. Hook up a voltmeter to this reference circuit and check for ~5V. If not 5V ....unplug each one of these sensors till you see it back to normal- then find which wires crossed or shorted

[BobiNHSV]

The ACP is from a Cadillac CTS-V. All of the 5V references are on the sensors. I have RPM (Crank Sensor), CMP pulses, Accelerator pedal moves throttle butterfly, 5V Ref to Throttle body, MAF/AIT, A/C Pressure (Not Used) Noid light on injectors and spark check on plugs. I have checked 12V bat and ign to all points. Checked wiring from J1/J2 to power outputs. This problem is obviously something stupid. I will talk to BP on the problem and see if they have any ideas. When the engine fires it runs up to about 1200 rpm and shuts down. Trying restart results in excess fuel (heavy smell).

[Jon S.]

I am confused.

The calibration in post #1 is for a 2009 G8 GT - running E38 ECM OS12633016 and T43 TCM OS24249179.

You stated your ECM OS was 1250228 - which is the HPT upgrade OS - that is not what you uploaded.

In post #15 you indicated the APP (Accelerator Pedal) was from a CTS-V.

You should be using the G8 GT APP - this likely the root of some of your issues.