2008 Pontiac G8 GT - auto to manual swap issues
12-30-2013, 04:45 PM
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2008 Pontiac G8 GT - auto to manual swap issues Hopefully some of you wise sages can point me to some troubleshooting that can help me figure out what is going on with the car. First some background...
I have spent the last year and a half trying to convert the car from an automatic to a 6-speed manual transmission. Most of this time was due to some delays in that I was originally trying to use a Camaro trans, but that didn't work out in the long run. So I have a complete transmission and all of the correct parts from a GXP that I swapped into the car. The mechanical stuff was relatively easy, but the electronics are turning out to be less so. During the conversion, I switched out the engine harness for one from a GXP so I would have all of the correct pin-outs for the harness and transmission connectors. I have sent my ECM and Body Control Module out for remote tuning and they are now installed in the car.
Current status:
- I installed the new ECM and BCM and was able to crank the car over to prime the oil pump
- I then installed the spark plugs and connected the injectors
- Tried to start the car and it would crank, but not start
- Further inspection noted that I was not getting a spark (was still able to crank the car at that time), and there was no fuel being commanded. I did have fuel pressure at the rail though.
- Posted my issues on one of the G8 boards and was advised to 're-synch' the ECM and BCM. This involved keying on the ignition for 10 min, turning it off for 30 seconds, and repeating 3 more times.
- After doing this procedure, I can no longer crank the engine.
- I can communicate with the ECM though the HPT software, but when I try to connect the VCM scanner, it connects to the car but I don't get any signals. Strange.
Codes:
P0107
P0118
P0122
P0223
P0641
P0690
Some of these I can explain as I know I have to have the throttle and brake recalibrated at the dealership. But I can't understand what could possibly be causing these other codes. I know this combination works, as there is another G8 with the same year and who used my notes to do his conversion, and his works fine. His benefit was that he did the tuning before messing with the hardware parts, where I didn't.
I have checked all of the wiring I can think of. The ECM connectors are tight, I don't have any blown fuses that I can see, and I'm kinda at my wits end. I would just rather see if any of you have any suggestions before I take it to the dealership with a blank check... I'm tired of working on this car and want to start enjoying it. Any help you can offer is very appreciated.
I have spent the last year and a half trying to convert the car from an automatic to a 6-speed manual transmission. Most of this time was due to some delays in that I was originally trying to use a Camaro trans, but that didn't work out in the long run. So I have a complete transmission and all of the correct parts from a GXP that I swapped into the car. The mechanical stuff was relatively easy, but the electronics are turning out to be less so. During the conversion, I switched out the engine harness for one from a GXP so I would have all of the correct pin-outs for the harness and transmission connectors. I have sent my ECM and Body Control Module out for remote tuning and they are now installed in the car.
Current status:
- I installed the new ECM and BCM and was able to crank the car over to prime the oil pump
- I then installed the spark plugs and connected the injectors
- Tried to start the car and it would crank, but not start
- Further inspection noted that I was not getting a spark (was still able to crank the car at that time), and there was no fuel being commanded. I did have fuel pressure at the rail though.
- Posted my issues on one of the G8 boards and was advised to 're-synch' the ECM and BCM. This involved keying on the ignition for 10 min, turning it off for 30 seconds, and repeating 3 more times.
- After doing this procedure, I can no longer crank the engine.
- I can communicate with the ECM though the HPT software, but when I try to connect the VCM scanner, it connects to the car but I don't get any signals. Strange.
Codes:
P0107
P0118
P0122
P0223
P0641
P0690
Some of these I can explain as I know I have to have the throttle and brake recalibrated at the dealership. But I can't understand what could possibly be causing these other codes. I know this combination works, as there is another G8 with the same year and who used my notes to do his conversion, and his works fine. His benefit was that he did the tuning before messing with the hardware parts, where I didn't.
I have checked all of the wiring I can think of. The ECM connectors are tight, I don't have any blown fuses that I can see, and I'm kinda at my wits end. I would just rather see if any of you have any suggestions before I take it to the dealership with a blank check... I'm tired of working on this car and want to start enjoying it. Any help you can offer is very appreciated.
12-30-2013, 10:11 PM
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1) Not sure what VATS is
2) Whiteautoandmedia did the BCM tune. This is a special service but it has worked for at least two other people now...
3) Honestly the electronics are the hardest part. I ordered all new GXP parts and everything was pretty much plug and play. The only thing that is non-restorable is the hole I had to cut in the firewall for the clutch. Round about cost is maybe $5k if you include parts, shipping, and needing to get custom tunes for the ECM and BCM.
I went with the GXP harness cause I didn't want to have to mess with splicing wires into the GT harness. I wanted this to be as plug and play as possible. That's why there are no custom parts in the hardware portion of this build.
2) Whiteautoandmedia did the BCM tune. This is a special service but it has worked for at least two other people now...
3) Honestly the electronics are the hardest part. I ordered all new GXP parts and everything was pretty much plug and play. The only thing that is non-restorable is the hole I had to cut in the firewall for the clutch. Round about cost is maybe $5k if you include parts, shipping, and needing to get custom tunes for the ECM and BCM.
I went with the GXP harness cause I didn't want to have to mess with splicing wires into the GT harness. I wanted this to be as plug and play as possible. That's why there are no custom parts in the hardware portion of this build.
12-31-2013, 08:39 AM
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So I did some research and successfully disabled the VATS via HPTuners. The car now cranks but still won't start. Some on the HPT forum are suggesting I need to take it back to the dealer so they can use the tech2 to relink the ECM and BCM. Sounds reasonable, but doesn't completely explain the issues I am seeing with the 5V reference signals all over the place. Going to try some electronic diagnosing on the 1st when I'm off work.
