Worth considering leaving the grey wires connected but connecting the LPG system in the 'normal' way without the grey wires might not affect starting etc and even if it did you could easily go back to having the grey wires connected. Same regards the 4000 rpm threshold, the petrol ECU might switch to open loop before 4000rpm anyway... But if it remains closed loop above 4000rpm, and if grey wires are not used, then since the LPG system intentionally holds mixture rich above 4000rpm the petrol trims for above 4000rpm will eventually go fully lean (which may be better than fully rich but unless you've seen what trims are already and confirmed they've gone fully lean above 4000rpm already the car could drive a bit flat above 4000rpm on petrol if grey wires are disconnected).Pinger wrote: ↑Wed Dec 02, 2020 1:17 pm
As far as I can ascertain my petrol fuel trims haven't deviated to the point of being problematic (it starts promptly on petrol) and I don't want to lose that.
If utilisation of the grey wire(s) is helping this should I consider just tagging the AFR meter to one of the O2 sensor wires?
This:''The mixer system may hold lambda voltage above 0.5v above 4000rpm,'' is a feature of mine. If not the 4000 rpm threshold then a (configurable) TPS threshold. That is one of the things I want to monitor (and tweak) with the AFR meter.
However you wire in the LPG system, if you wire in an AFR meter it will need to connect directly to lambda signal voltage - But usually an AFR meter (at least if it's wide band) will need it's own (wide band) lambda sensor. Your truck's current lambda sensor must be narrow band if the mixer system connects to it. Some AFR meters allow you to replace the vehicle's narrow band sensor with AFR meter kit's wide band sensor, the AFR kit can then output a narrow band equivalent voltage for the petrol ECU and Millenium etc to connect to (as if a narrow band probe is still fitted).