Please Help
Thread Starter
Staging Lane
Joined: Jul 2011
Posts: 68
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Please Help I've spent hours searching, but I guess the combo I a using is a little unique.
The car is set to debut at a fairly big show for my area in 2 weeks. I just finished it and got it running, but had several codes. banks 1 and 2 too rich, random misfires, mass air volume fault, etc.
I initially ran a mail order tune to at least get it running then I took it to a local, well known tuner for my area for what was supposed to be an easy, one day tune to dial it in. That has turned into a nightmare.
In a nutshell, the car will not accelerate past 4000 RPM and there were other issues the tuner didn't like about the mail order tune so he reflashed it back to stock using a 2008 Silverado baseline, tuned out the DTCs and permissives my setup doesn't need or can't use. Turns out every time you start the car, the ECM is trying to do a crank relearn procedure, but it is not completing.
Narrowed it down to possibly the brake on signal which I do not have. We have been talking to the harness builder and the mail order tuner to figure it out with no luck. He tricked it once by inputing false data and got the car to run great; however, if you shut it down and restart it, it immediately goes to the limp mode 4000 rpm limiter and misfires.
Now, the current tuner thinks it has to be the ECM, but none of us thinks it is that since it is a brand new ECM from GM. He said that even if he applies a 12V signal or turns off the DTC for that, the ECM still doesn't recognize the signal and thinks the brake is not applied.
SETUP: 2008 LH8 with LS2 intake and fuel rails, TKO 600 trans, new GM E38 ECM, new GM 25168491 MAF sensor, C6 Vette DBW gas pedal, TB from the 2008 donor (truck), and etc.
The original tuner used HPT and an OS for a 2008 Silverado with changes to convert to manual trans. Current tuner reflashed it back to stock using SPS and used a truck OS. Still has the relearn issue and wants me to buy another E38 ECM. I'm not convinced it is the ECM. This is getting ridiculous. 2 tuners and my harness builder are totally at a loss. WTF?
Any ideas?
The car is set to debut at a fairly big show for my area in 2 weeks. I just finished it and got it running, but had several codes. banks 1 and 2 too rich, random misfires, mass air volume fault, etc.
I initially ran a mail order tune to at least get it running then I took it to a local, well known tuner for my area for what was supposed to be an easy, one day tune to dial it in. That has turned into a nightmare.
In a nutshell, the car will not accelerate past 4000 RPM and there were other issues the tuner didn't like about the mail order tune so he reflashed it back to stock using a 2008 Silverado baseline, tuned out the DTCs and permissives my setup doesn't need or can't use. Turns out every time you start the car, the ECM is trying to do a crank relearn procedure, but it is not completing.
Narrowed it down to possibly the brake on signal which I do not have. We have been talking to the harness builder and the mail order tuner to figure it out with no luck. He tricked it once by inputing false data and got the car to run great; however, if you shut it down and restart it, it immediately goes to the limp mode 4000 rpm limiter and misfires.
Now, the current tuner thinks it has to be the ECM, but none of us thinks it is that since it is a brand new ECM from GM. He said that even if he applies a 12V signal or turns off the DTC for that, the ECM still doesn't recognize the signal and thinks the brake is not applied.
SETUP: 2008 LH8 with LS2 intake and fuel rails, TKO 600 trans, new GM E38 ECM, new GM 25168491 MAF sensor, C6 Vette DBW gas pedal, TB from the 2008 donor (truck), and etc.
The original tuner used HPT and an OS for a 2008 Silverado with changes to convert to manual trans. Current tuner reflashed it back to stock using SPS and used a truck OS. Still has the relearn issue and wants me to buy another E38 ECM. I'm not convinced it is the ECM. This is getting ridiculous. 2 tuners and my harness builder are totally at a loss. WTF?
Any ideas?
