S15 inconsistent o2 feedback/control

[nickbucher]

I've been using my aem uego to simulate the o2 sensor for about a year now, but lately it's suddenly stopped controlling the mixture at idle. It sits at 0.35 volts +-0.02 which means I'm stuck on an afr of 18+. O2 control works perfectly when I'm driving and will cycle between 14.9 and 15.3.

Is there a map which affects this? I've tried clearing self learn but that had no impact. I don't think there are boost leaks as afrs on boost are the same as always

[Matt]

There isn't a map that I know of which is idle specific

[raddy]

try to physically unplug ecu o2 feed and compare voltage output in nistune. In case of ca18det is 0.35mV reported when is oem sensor unplugged...this can point you to the source of failure.

[nickbucher]

I ended up doing a boost leak test and found all 4 runners of my mazworx sr20ve manifold are split and pulling in heaps of extra air. I think at high vacuum at idle it's just running so lean that it's beyond the o2 sensor's scope and it doesn't attempt to correct. Possible? Still doesn't explain my it shows 0.5v sometimes when it's off the scale. I'll fix the manifold and then rewire the wideband

[Matt]

Try it out. Doesn't make sense from the ECU side of things for it to suddenly do that, so external factors are most likely the cause