EVAP CEL spoofing questions
 

I have installed a 2000 YM AP1 into an early MGB. The engine is bone stock and the fabricated header, exhaust, and air intake are very similar in flow and function to a stock AP1. I am hoping to successfully manage the engine with the original ECU. I have proven workarounds for the immobilizer, the air pump system delete, the alternator load detector delete, and the downstream O2 delete (I have no catalyst). The car does have to pass any emission testing; I merely want good engine behavior and OE AP1 driveability and would love to have a functional MIL (not illuminated because of the absence of a functional EVAP system). I think I have the other MIL issues worked out.

I have studied the service manual for clues and have some ideas of what might possibly help avoid some (or all??) of the EVAP CEL codes from illuminating the MIL. I welcome any advice or wisdom from anyone who can correct my thinking or shed light on what might be successful. I know I could operate the engine with a stand alone, but I am trying not to have to go there.

The only EVAP related codes tracked by the YM 2000 USDM AP1 appear to me to be as follows:
P0451- FTP range
P0452- FTP low voltage
P0453- FTP high voltage
P1456- Fuel tank vapor leak
P1457- Canister vapor leak

Here is what I am currently thinking:

The ECM is sending a 5V reference to the FTP and expecting to get about 2.5V back to the ECM when the Fuel vapor pressure is fairly normal. I think I might be able to give the ECM this voltage signal by supplying a well chosen resister in place of the FTP device.

It appears that the ECM does not "ready" the leak check monitors and start the leak checks if the fuel level is more than 3/4 full. If I send a "full" resistance value (11-13 OHMS) to the fuel level terminal of the ECU, would this prevent the monitors from thinking the conditions were right to test for a leak?

I can let the ECU operate the three solenoids (Canister purge, Canister vent, and EVAP bypass). The ECU can know they are there.

I need wise counsel feedback from anyone who knows what the system is looking for. Please share your wisdom. Thank you!

Were you ever able to get an answer to this question? Looking to do something similar.

Thanks!