R0B wrote: ↑08 Dec 2024, 10:44
I was told the kit improved MPG. Hence my reason for asking if anyone had fitted the kit. But as you are more knowledgeable than myself, I will take it MPG won't be improved.
Digifant already caters for stoichiometry so I don't see any base for fuel saving. Next step would be to eliminate/reduce intake manifold/port wetting by dropping batch injector firing and adopting sequential injection. (ISBN: 1-55788-365-3 Bosch Fuel Injection Systems: p. 71)
Digijet will benefit from the stoichiometry, but will the ignition map be compatible?
Having *any* closed loop lambda control is a *massive* step over digijet which is basically an electronic simulation of a carburettor, using crude airflow measurement to work out the injector pulse width. It uses engine RPM and temperatures to improve driveability a little.
Having *proper* closed loop lambda control is a step above digifant which has a lambda sensor, but primarily to try and avoid annihilating the catalytic converter when using the same crude air flow meter. The ECU has quite a limited range of adjustment, and the lambda control is only used under part throttle.
Beyond the mixture control, there's more to economy than just targeting stoich - good, keen ignition timing will improve power by a good 5% or more, from the same fuel input.
With coil on plug, accurate ignition control, wideband o2 sensor, modern throttle position and inlet manifold pressure sensors then I see no reason why there won't be a very noticeable power and efficiency gain.
TwinTurbo wrote: ↑11 Dec 2024, 18:19
Digifant is open loop , so there are gains to be had goign closed loop and the MM kit does include a wide band lambda.
Digifant is a derivative of Bosch L-Jetronic and most definitely NOT "open loop".
Anyway, feedback or rather the lack of feedback from TheSamba seems to suggest that going from a narrowband to a wideband O2 sensor is not the Holy Grail.
