1989 Mondial t Dyno run!

Well I wouldn't says only 5 minutes to actually get the chip out. To get the unit out from behind the seat maybe its would take 5 minutes but to actually get the chip out and replace it with a new one is more like 30-45 minute job because of how they packaged the unit.

 

It's difficult to say. None of this is documented in public, so we pretty well have to figure it all out from scratch on our own (major hassle). The values stored in the fuel maps seem to go no higher than 150, even though there is room to store numbers up to 255.

These values, for the partial throttle fuel maps at least, are the "base" numbers that are the factory's guess at what will give you a Lambda of 1 (stoichiometric 14.7 to 1 air to fuel ratio).

But...

The Motronic is dynamic. It watches your O2 sensors and adjusts. So those values serve as a reference for the Motronic ECUs...and they would be used if the ECUs lost the signal from the O2 sensors...

Otherwise, the system will often be making fuel adjustments independent of those partial throttle fuel maps.

I'd dare say that you could remap the partial throttle fuel map tables and see no typical difference in an O2-working 348.

However, no doubt that the full throttle maps matter, as the Motronic ECUs ignore the O2 sensors at full throttle. So for ignition advance and fuel at full throttle, what's on our chips most certainly matters.

 

Let me try again, as I probably botched my explaination above (sorry).

The targeted A/F ratio is 14.7 to 1 for the 3d partial throttle fuel maps. Those fuel values in the partial throttle map are guesses at what would give you that stoichimetric air/fuel ratio (lambda of 1).

Those guesses are used as a reference by each ECU, but are generally overruled at partial throttle by the O2 sensor's report of your air fuel ratio. Our Motronic ecus correct our fuel injection at partial throttle based upon the O2 data.

 

Thank you for taking the time to explain. I would have thought that at full throttle and even some higher partial throttle settings the target AF would be closer to high 12s ot low 13s for better power, as max power occurs around 13.2 or so depending on who you talk to. The o2 feedback then tweaks up or down off of the base rate. except at full throttle.
Of the dyno full throttle AF maps, Motronic seems to steadily decrease the AF to somewhere in the high 12s by redline.
I guess the lambda maps are somehow tied to duty cycle of the injector signal.
Again - thanks for the explanation!

 

Yes, the target A/F ratio at full throttle is much different from the 14.7 targeted for partial throttle.

Yes, the O2s tweak for partial throttle, not for full throttle.