LS3 map sensor with LS1 harness/ecu issues!

[Matt_lq4]

2000 Camaro Ls1 with Ls9 supercharger. I'm having issues when using an LSA 3 bar map sensor with an LS1 harness and PO1 ecu despite the proper 3 bar linear and offset entered in. This is with the 3 bar OS flashed in.

For troubleshooting purposes, the Ls1's ecu was reverted to its stock 1 bar OS.
I believe an LS3 and LSA map sensor have the same pin designation so although we will need to use an LSA 3 bar map eventually, I am using an Ls3 map sensor for testing purposes. Entered the LS3's 128 Kpa linear and -0.3 offset.

Pin C (the closest one to the engine) of the Map connector was to see 5 volts (key on engine off) whether on an LS3 harness or LS1 harness, this was confirmed at the connector w/engine off.

The weird part is the 2 outside wires, we swapped them both ways but the map sensor just reads 26 Kpa key on engine off, AND when running. When we flip those outside wires, it reads a higher value but also stays fixed with no change.
Even if it was a linear/offset issue, you'd expect the values to at least change from idle blips or shutting off the engine.

He wired in his ls1 map sensor, and it works perfectly. Key on engine off 100 kpa, then when running it fluctuates as it should and shows a realistic value at idle.

[blindsquirrel]

screenshot.25-02-2023 14.33.35.png

[Matt_lq4]

Thank you kindly! Everything I found yesterday on google for ls3 map sensor wiring was steering me wrong.

[blindsquirrel]

It's amazing how much easier it is when you have the factory manuals. And amazing how hard it is if you don't. Unless your wasted time is worth zero dollars, it'd be cheaper to pay the $20 for 3-day access thru ACDelcoTDS.

[Matt_lq4]

I will invest in the manual for next time after this fiasco, I appreciate the help.