engine wont start on 4l80 tune, runs on 4l60

[BagD72Chevy]

I have a 4.8 engine swapped into my 67 C1500. Blew up the 4l60 so swapped in an 80. Changed wiring harness for 80 and segment swapped tune but it wont start on the 4l80 tune. I also swapped the cam while it was down. Any ideas?

More Info:

4.8L truck motor from 07 classic silverado with cam
4l80e trans, HD2 shift kit, Circle D converter

Truck will start by opening throttle a tad while cranking on the 12613248 OS with 4l60 trans segment. (attached 4l60 tune)

Swap trans calibration and trans diagnostic segment for 4l80 to 12613248 OS and truck will not start. (attached 4l80 tune)

Since I am going to put a blower on anyway I went ahead and made a tune with the 12592618 OS so I can go to Custom OS later. This OS seems to be more widely used. I attached this tune and cranking log in Post #4.

Next steps:

1. Full Flash 12592618 OS with 4l80 segment --- NO START
2. Flash stock 12592618 OS with 4l60 segment and see it will start. (Try to isolate the trans)
3. Flash stock LQ4 12592618 OS with 4l80 and see if it will start.

Other Actions:
Check PRND switch is operating correctly. It is wired in but ignition switch goes straight to starter so it could be acting weird. WORKS PERFECT

[joecar]

Try doing a full flash.

[BagD72Chevy]

Thanks Joe, I tried that. I tried it again this morning again and no go. Flash the 4l80 and it cranks and sputters but wont start. Sometimes doesnt even sputter. Flash 4l60 and it will start. This has really got me baffled. My OS is 12613248 which doesnt seem to be too common to me. Should I try to flash it with an older OS?

[BagD72Chevy]

Ok, before I chase down that rabbit hole too long I made a new tune with the 12592618 OS. Did a Full Reflash to the PCM and tried to start, failed to start. Attached is tune and log.

[joecar]

Thanks Joe, I tried that. I tried it again this morning again and no go. Flash the 4l80 and it cranks and sputters but wont start. Sometimes doesnt even sputter. Flash 4l60 and it will start. This has really got me baffled. My OS is 12613248 which doesnt seem to be too common to me. Should I try to flash it with an older OS?

Try doing the segment swap afresh.

If you do try it with an older OS, will you be able to find a 4L80E segment from the same OS id...?

[joecar]

Ok, before I chase down that rabbit hole too long I made a new tune with the 12592618 OS. Did a Full Reflash to the PCM and tried to start, failed to start. Attached is tune and log.

Weird... are the injectors and spark plugs firing...? Is VATS kicking on (can tell by looking at the STATExx pids)...?

[joecar]

What PCM do you have...?

[BagD72Chevy]

What PCM do you have...?

PCM is 12586243. 4.3 Truck PCM or express van. It has the hardware in it for manual a/c activation rather than just Serial A/C.


To get even weirder I made post #4 at lunch. I got home from work and turn the key on, notice no fuel pump prime. Turn key off. Turn key on, no fuel pump prime. I decide to crank it to see if pump will come on and its started. No change from the no start state from earlier post.

Started 3 times in a row. I made a log of it incase that would be useful. So Im assuming the tune I segment swapped in original post is corrupt or something. But now o the 05 OS it is throwing code U0107. My TAC module is mounted right next to pcm inside truck so I know the connections are good. After that I found this thread which leads me to believe that my 07 TAC/Pedal wont work with my 05 OS that I need for COS and the blower. Hmm...

https://forum.efilive.com/showthread...rado-questions

[joecar]

Yes, it like an impossibly complex jigsaw puzzle...