O2 Feedback

[89CAL]

Will have a look tomorrow. But I think I'll just run lean cruise straight from the tune

[Don Dada]

I have O2 feedback on (pfc) and it cycles between 14.1-15.7afr when cruising, and yes i can feel the change in the "beat" of the engine similar to what Hanaldo is describing, and it clearly goes in time to when the gauge cycles from lean to rich and back

Sometimes it is worse than others but it is noticeable....never paid attention to when it is worse so i dont know if its related to operating temp but i'll monitor it now to see

Either way I just thought that it was normal due to the engine getting varying amts of fuel from being in closed loop as my O2 sensors voltage looks good and cycles as normal .........it does not do it if I turn off O2 feedback

[Hanaldo]

But my o2 sensor is not connected, should my afr's still be cycling?

[Don Dada]

hmmm..not connected as in not wired?

[Hanaldo]

hmmm..not connected as in not wired?

Effectively, yes. The sensor itself is still in the dump pipe, but the harness has been unplugged. When connected it gives a lot of trouble, made it impossible to tune.

[Don Dada]

Well then there is no possible way of the ecu seeing a voltage input so I cant think of any reason why the afr would cycle... just saying even if O2 feedback was indeed on and seeing erratic readings from the dud sensor when in closed loop

Sounds like you have similar symptoms but a different issue

[GTSBoy]

It is not unknown for the wire that powers the heater in the O2 sensor to melt through and short the signal wire. You shoud check that loom from end to end to see if it good or bad. I can imagine it possibly feeding voltage or short to ground to the ECU if there is something wrong and seriously messing with the feedback.