Floor guy

Currently, my car has a replacement (Bosch heated type) narrow band installed in the #7 header tube. It is located approx. 1/2 way between the collector and the flange.
It has been behaving normally for a couple of years.

While working through the tuning process, I was able to get the PE adjusted to the desired (approx.) 900 mv.

Slid a wideband in the muffler, using one of the Innovative holders than thumbscrew to the pipe.

When I am high in the rpm at WOT the wideband shows 11.0-11.5 when the narrow band shows approx. 900 mv.
As you can guess, I am wondering which one to trust. My gut tells me the wideband.
Does the wideband read differently at the rear of the exhaust system vs. say, in the collector?
Thoughts on the subject would be appreciated.

Six_Shooter

iTrader: (2)

I'm not seeing the issue.

900mV on the NB would be on the rich side, potentially around 11:1. There is no direct correlation NB voltage and AFR due to the transfer function of the NB, it's more like a switch than a sensor, that has a definable voltage function to value. 900mV could be 11:1 or could be 12:1...

Do you have a catalytic converter? WB sensor don't work well after a cat.

Floor guy

No cats on the car. True duals.
My gut tells me to trust the wideband, but was not sure how accurate it is in the rear vs. the front.
Assuming WOT, I would guess that it would read similar, but maybe reading slightly lean at the rear. I have read some threads that said it may be reading 1/2 point richer at the back of the car though. Not sure which piece of equipment to put my faith in.

Ronny

iTrader: (1)

I would believe it should read the same A/F unless it is idleing. I have never seen a comment to the contrary.

Orr89RocZ

iTrader: (20)

I have seen 1/2 point richer or so readings on header collector widebands and some dyno tail pipe widebands. They can vary based on brand and calibration but should be reliable compared to a narrow

I tuned a car that was high 10's to 1 air fuel and narrow band was 950-960 mv. I eventually got it near 12.8 but narrow band read weird values like 730 mv. I didnt trust the nb. Car ran hard at the track.

My L98 bolt on car i was in the 870's mv range and was snow white lean on exhaust valves. Dyno read 14.5 at wot... 900 mv is a starting point.

Ronny

iTrader: (1)

I was refering to WB sensor location at tail pipe vs collector.