afr bank 1 showing 0 at times

[Zona14Stang]

Has anyone seen afr bank 1 go to zero for a second or two on datalogs using the SCT X4 and laptop? I was data logging my latest tune and all my knock sensor problems are gone. The only thing I notice is at low rpm when you accelerate by pushing down anywhere from 1/4 to 1/2 throttle I get a slight bog then t goes. I do not see any knock sensors going of but on one log I see it go to 0 on one of the banks. What should afr be at?

Could this just be a logging thing or a don't care? or do I have a bad 02 sensor?
Or is AFR 0 good ?
so according to wikepedia LOL..

2 is running rich.. and my value of 0 is lean

Air–fuel equivalence ratio (λ) [edit]
Air–fuel equivalence ratio, λ (lambda), is the ratio of actual AFR to stoichiometry for a given mixture. λ= 1.0 is at stoichiometry, rich mixtures λ < 1.0, and lean mixtures λ > 1.0.

There is a direct relationship between λ and AFR. To calculate AFR from a given λ, multiply the measured λ by the stoichiometric AFR for that fuel. Alternatively, to recover λ from an AFR, divide AFR by the stoichiometric AFR for that fuel. This last equation is often used as the definition of λ:

\lambda = \frac{AFR}{AFR_{stoich}}
Because the composition of common fuels varies seasonally, and because many modern vehicles can handle different fuels, when tuning, it makes more sense to talk about λ values rather than AFR.


Guess I answered my own question have to talk to my tuner to verify
Has anyone seen this big of a difference on their measured AFR's??

 

[Tron84]

Yes, I've seen pretty regularly where one of the banks will read 0 for a split second.
I've always taken it as being an erroneous reading and not worried about it. My tuner has never said anything about it either.

 

[Bluegoat06]

You do not need to worry about measured AFR at part throttle, at part throttle close loop is keeping the fueling at stoich for the most part, (lambda=1), you want to look closely into long term fuel trims, they should be around +-2% or +-3%, for idle/part throttle when tuned, you can see 6-8% out of a bone stock car, something I didn't know because about this Coyotes is that Ford runs this vehicles in permanent close loop state (as opposed to what I know from GM and LSx engines where the PCM will switch to open loop at WOT), so you can observe your fuel trims on a say 3rd gear run, as long as your fuel trims are 0 or slight negative at WOT, you are more than fine, you don't want + LTFT's at WOT, lambda at WOT should change to 0.82-0.83 tops for max power in this platform.

 

[cb900f]

In the other logs I viewed from you, it's always been Bank 1 that zero's out on the measured AFR and seems lazy on WOT. On WOT Bank 2 would be at .82 lambda, but Bank 1 would be at 1.05 until about 3700 rpms. I would swap the O2 sensors and see if it follows the O2.

 

[tennis_pr0]

I've seen th max value of my measured afr bank 1 and 2 go to 2. Now that would be basically a 28:1 afr ratio which would basically blow my engine up, so in assuming it isn't accurate and it just a sensor spike or something like that

 

[jn2]

I've seen th max value of my measured afr bank 1 and 2 go to 2. Now that would be basically a 28:1 afr ratio which would basically blow my engine up, so in assuming it isn't accurate and it just a sensor spike or something like that

Usually occurs under declaration where it would go lean since there is practically no load on the engine. Quite normal, if you have the LCD screen with gauges you will notice the a/f will read 20:1 as well.

 

[AKDMB]

My 3.7 has done this (measured lambda just goes to zero) several times and I have caught it in logs. Don't know what it is. It was completely random, didn't affect the car at all. Car drives fine and no other values are affected when it happens. IIRC it might have been both sensors that did it. Some logs I would see it others I wouldn't. Haven't logged in a while, it doesn't appear to be an issue whatever it is. Just to be clear the car isn't leaning out when this happens, either the sensor is going bad, or its a logging issue, in which case SCT and HP Tuners, has the same glitch. If the car cut fuel during normal driving (not talking decel here) you would notice it.