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Afr not making sense

Understanding AFR

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just installed a brand new aem uego wideband sensor into my evo 9 running a link g4 plus plugin ecu. The wideband gauge seems to work, I’ve run the white analog positive wire to pin 71 which is my an volt 4 pinout and the original o2 sensor wire however I didn’t have any o2 sensor before installing the wideband so I thought this would be perfect! The brown negative analog was run to ecu pinout 46 which is the ecu ground! After configuring on pc link the lambda doesn’t match up with the gauge it stays around 0.170 whereas the gauge displays 0.78 on idle! When I try to lean out the idle the car doesn’t want to run at all. It only idles we’ll at 0.78/0.82 lambda, can anyone suggest what the issue might be as I’m really stuck on this.

You've got two things going on here. First, what is the standard method for wiring up a wideband to this ECU? Does Link recommend you wire it up as you did, to the o2 sensor pin?

Second, what mods have been done to the engine, and what idle speed are you at? When you say it doesn't idle well does that mean it stalls, misfire or what?

I asked the question on this forum and seeing as it’s an analog channel that wasn’t in use I fail to see any issue with using it. The cars a built 2.3l on speed density running open loop as it never had o2 sensors until I put the wide band in. Idles at 1000rpm but lambda is at 0.8 at idle and when I lean it out it will start to stall

Do you have stock cams or higher overlap cams? As for the MIVEC, is it working? Anything that increases overlap will deteriorate idle and likely require you to run rich of stoich or make some other compromise.

Somebody from Link can chime in regarding the wideband, I don't have expertise in this specific ECU as far as wiring.

Alastair, can you post up your configuration file? Want to have a look at your o2 sensor calibration settings :-).

Hi Zac, yes mate I sure will as soon as I’m home! Any help on this subject will be great, not happy with how the car is running, my gauge reads 0.8 lambda just at idle, I am running larger cams but that’s no reason to be running this rich. when I try lean it out to around 0.95 and rev the car, once the idle comes back down it drops below 600 and almost stalls the engine