anyone reprogram an EEC-4 OBD-1

[ByronRACE]

If the guys at Massflow are running a stock PCM, then we already know what the resulting MAF curve being fed to the PCM is.

It's the factory ford 19lb/hr curve scaled to whatever the change in injector size is...exactly the same thing they do on 5.0L mustangs. The only detail in this case is that this "scaling trick" is being done in a frequency to voltage converter box. In a Ford MAF they calibrate the analog electronics to scale the voltage. The massflow guys do something else. They probably use a microcontroller, calculate the frequency of the GM MAF output, then use an internal lookup table to look up what the output voltage should be, and produce it using a digital to analog converter. This allows them to put anything they want in the lookup table and translate any GM input curve to any Ford analog output curve; and scale it for any size injector. That's a lot of work, but it lets them use off the shelf stuff that's easier to cram into an air filter than the Ford design. This lookup table would also allow them to avoid hitting the .4V minimum voltage that flags a check engine light when you use the "scaling trick" on big injector engines. Once you get beyond about double the factory injector size, you start hitting that .4V in the idle range and the PCM goes into limp mode. They probably flatline the output above .4V to avoid this...so they can make 40+lb/hr injector calibrations run on factory PCMs.

Anyway, if you're running a factory Ford pcm (look at the prom like I suggested for signs of tampering), we know what curve is being fed to the PCM. One less thing you have to ask for.

Byron