Hi All. I just fitted a mixture meter to the oxygen sensor in my Ralliart and kept an eye on it while driving in the country. The ECU stayed in closed loop mode ie stoichometric, the whole time.

A couple of years back I had the same meter (constructed from a kit) on my TJ Exec, and when driving above 70km/hr with a steady throttle for a period of time, the ECU would come out of closed loop mode and go to constant lean mixture for good economy.

Can anyone confirm whether the Ralliart motor ECU tune has lean cruise or not.

Cheers

Hi All. I just fitted a mixture meter to the oxygen sensor in my Ralliart and kept an eye on it while driving in the country. The ECU stayed in closed loop mode ie stoichometric, the whole time.

A couple of years back I had the same meter (constructed from a kit) on my TJ Exec, and when driving above 70km/hr with a steady throttle for a period of time, the ECU would come out of closed loop mode and go to constant lean mixture for good economy.

Can anyone confirm whether the Ralliart motor ECU tune has lean cruise or not.

None of the TJ onwards ROMs I've seen have anything like a lean cruise function (I've looked because I'm interested in such a capability). Unless modified they will not drop out of closed loop except at high revs or high load.

There are probably other explanations for the effect you saw, such as a failing oxygen sensor (when they fail they report lean).

I'm fairly convinced the Exec had lean cruise, it would only come in under certain conditions and would revert immediately to closed loop if you went outside those conditions.
I recall the 380 did not have lean cruise because it met the Euro 3 emissions requirements and lean cruise would have given slightly higher nitrogen levels.