manual swap G8 GT ECU thinks it's going 158mph at all times

[zygee]

Forward: Sorry if I posted about this before, I couldn't find any emails about it so idt I did but idk. Also sorry if this isn't the right place to put this, it seemed about right though.


So my T56 Magnum XL swapped car runs and drives pretty well, goes sideways when I want it to, etc.


I get a good speedometer reading from my ABS sensors. I've also hooked the T56 speedo sensor to the ECU where the manual speedometer sensor would go to (had to add a couple pins).


For whatever reason the ECU thinks it's going 158 mph at all times. It makes it so that it won't go past 5770RPM as well.


I had a decent tuner try to Dyno tune it which is where I initially found this out.


Any ideas what could fix this? The tuner said it might be from having the TCM jumped from early in the swap so the ECU would think the TCM is still connected.


Idk, I thought some people who've swapped just left it plugged but I think I've heard you don't need it once you're tuned.


Any ideas?

[TA427]

Did you hook the 2 speed sensor wires to ECM X1 connector terminals 71 and 72 ? They are between the light blue fuel sender wire 70 and black ground wire 73 if you did start with a manual GXP tune as the ECM is doing 4X the speed buffer