The starting point for the conversion was measuring both, the output of the original AFM connected by pipe with the Volkswagen Pierburg MAF, outside the car for different static airflows (using an adjustable garden vac
). This provided the first plot. For the coding also algorithms to avoid double compensation of air temperature (already done by the ECU) and controlling the fuel pump were needed.
Next step was to test the behavior in driving conditions. Here for instance it turned out that the dynamic behavior of the Pierburg MAF required some fatter AFR at low end compared to the original. This was quite a surprise, because the response time of the MAF according to Pierburg should be in a range of <50ms, the Converter works with 16MHz and recalculates signals in around 10ms. Both pretty fast, but I guess this is quite normal in building ECU maps and optimizing behavior between parts.
We then also did some logging of the AFR together with rev and throttle position/vac to validate the behavior. The goal was to follow the original characteristic as much as possible whilst creating the best power output when revving up under full throttle.
Never put it on the dyno, but recent feedback was, that the power of the 1.6 NA with Converter is very close to the 1.8 NA ( from a guy who owns both).