Been chasing an intermittent miss at idle, and seem to have that under control now. Removed the original (32+ year old!) narrowband O2 sensor, and hooked it up to my wideband's simulated narrowband output. Thought the car ran great afterwards, but only took it out for a minute. Another drive and some further messing about revealed some odd behavior of the A/F gage readout. Borrowed my buddy's laptop & loaded up WinALDL to take a look.

My AEM UEGO wideband's gage readout demonstrates that the sensor can tell rich from lean & display A/F accurately (AFAIK) as I vary fuel pressure @ idle, so the sensor itself appears OK. However, the ECM is only seeing a constant .433 voltage from the UEGO's 0-1V simulated narrowband output - no fluctuation whatsoever - and therefore the ECM isn't varying injector pulse width to adjust A/F ratio. The gage shows the ratio leaning out, possibly dangerously so, in cruise...until I floor it, which of course puts it in open loop & extremely rich.

The gage doubles as the sensor controller, and has several output modes. I am set to P04 which is 0-1V Nernst cell (narrowband) simulation, so it's not an issue of running the wrong calibration. I'm just getting no rich/lean counts or voltage fluctuation...straight .433 to the ECM, regardless of actual A/F ratio...anyone know why?

The old narrowband O2 is sitting in its bung disconnected. Its wire is capped off, and the white 0-1V output wire from the WB gage is spliced into the purple O2 input wire at the ECM. Don't think I got the wrong wire either...could only find one purple, in one of the ECM connectors. Am I missing something...do I need to ground that factory O2 wire?

Either I have a wiring problem of some kind, or the simulation isn't working properly. If anyone has experience running their car on a wideband sensor's simulated narrowband output, your input would be much appreciated! I've been reading about many who have had issues getting their car running properly with this arrangement, though, so perhaps as practical as it sounds to me, it may not be in reality.

Might have to suck it up and purchase a replacement narrowband, and just keep the 2-sensor setup...but I can't help thinking why have 2, if 1 can (supposedly) do the job?

 

Well, I've done a lot more reading on this, about people who have tried this arrangement to run the engine with their AEM UEGO...and the consensus almost always seems to come to AEM having done a poor or incomplete job with their 0-1V narrowband sim, and that I'll be much better off just running a stock narrowband O2 for ECM input.

Here and there I found a few who said it works for them, but very few details as to how, or how well. One looked promising, in that he got it to "work" after grounding the OE O2 sensor ground in the ECM...but that was on a vehicle with a factory 4-wire sensor that actually has a ground wire. With a 1-wire sensor, there isn't really much else to try...it's either connected, or it isn't.

So, buyer beware with the AEM unit...it seems to work fine as a standalone, but the narrowband sim is essentially useless...you WILL need to retain your factory narrowband. Off to NAPA to pick one up!