I have a 1977 Z and moved from sea level to a mountain town at about 6,000' elevation. Thanks for the inputs on the old thread I relocated this from.

Question:
If the AFM is insufficient at compensating for high altitude operations, and the optional "California model" came with an automatic bellows that closed the circuit between pins 9 and 12 of the ECU wiring harness, will physically closing the circuit with a jumper lean the fuel/air mixture by the 6% that the bellows circuit achieves? If it will not, then that would mean the ECU's are programmed differently between models.

My goal is an effective and expedient leaning in the near term.

In my first trial, I successfully implemented a delicate jumper of 20-gauge wire and electrical tape (which deftly fit around the pin blades that inserted into empty pin slots) for the wrong pins. I am aware that my higher altitude daily operating environment (between 5,000' to 8'000') is going to be a rich-running problem (I have burned 1/2 a tank of fuel to go 75 miles). Options identified include:

a) replace EFI with carburation
b) upgrade to a turbo
c) manually adjust the global fuel curve at the AFM cogwheel (with a wideband AFR gauge)
d) jumper pins 9 & 12 at the ECU harness

I am deeply interested in the recommendations and lessons learned of those who have worked on high altitude solutions.

2 hours ago, Gary H said:

will physically closing the circuit with a jumper lean the fuel/air mixture by the 6% that the bellows circuit achieves? If it will not, then that would mean the ECU's are programmed differently between models.

If I was trying this I would use the wires on the back of the connector, if they are there, and use a switch or manually connect and disconnect the bare wire ends, to see if there is an effect while the engine is running. I'd guess you would hear a change at idle RPM.

I might also take the cover off of the ECU first and see if the two terminals are connected to the circuit board. If not, there's no point.

These old analog computers don't really have programming (except for maybe that one chip that has come up in discussion in the past), they have circuit schematics that are implemented in the ECU. You get whatever they soldered on to the board.

If you don't have a functional CA ECU you might be able to find one out here somewhere. Interesting project, good luck.

Edited 58 minutes ago58 min by Zed Head

Here's a good thread about ECU's and their pins. CO describes pins to nowhere at the bottom of the first page.

https://www.classiczcars.com/forums/topic/60678-what-are-the-facts-about-280z-ecu-compatibility-and-differences/

You could even leave the cover off and run some jumpers to the pins. They are labeled on the inside.