NTK AFRM Reads Rich at Idle

Just installed my new wideband in my 2007 Z06. I wired the positive and ground directly to the battery and added a switch to the positive wire. Then I attached the ground and signal wire to the HPtuners box. I was pleased to find that the box matches HPtuners, but it's reading about 0.85 lambda at idle. At cruise it reads 1 and if I give it a little gas at idle (1000+rpm) it also reads 1. WOT also reads what I expected. Any idea why it would be reading so rich at an idle of around 800 rpm?

I'm wondering if it's because I have the wideband directly after my cat on the drivers side. Unfortunately, there was no room to put it in front of the cat, but I could remove my narrowband and use that.

When it reads incorrectly, fuel trims are good and commanded lambda is 1.

I'm thinking it probably isn't a calibration issue since I would think it'd be off across the board, but I'm not sure. It just really seem like it's not reading properly when the exhaust flow is low.

Well, you arent suppose to install a wideband before the converter. Everyone I've seen says it needs to be installed prior to the cat. Moistures or even like stored oxygen in the converters can scew readings.

Did your wideband come with instructions?

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Originally Posted by 5FDP

Well, you arent suppose to install a wideband before the converter. Everyone I've seen says it needs to be installed prior to the cat. Moistures or even like stored oxygen in the converters can scew readings.

Did your wideband come with instructions?

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Yes I know it isn't ideal. That was the only advice I didn't follow, but like I said there really isn't room for one before. I'm probably going to try putting it in the pre cat o2 location tomorrow to see if that changes anything but it's going to be a big pain by the looks of it so I thought I'd ask on here first in case someone has run into a similar issue.

I moved the wideband to the drivers side front O2 bung and it seems to be reading correctly now. Thanks for confirming the issue. Guess there's a reason it's recommended to be BEFORE the cat.... Kind of a hassle having to swap between wideband and narrowband though. Guess I'll have to get some headers.

Further to having to swap back and forth between the two - without a second bung you cannot use the NarrowBand to validate the accuracy of your WideBand at λ1.