So I'm currently getting an e-tune from Jeff Evans. One of the datalogs he requires is a 10 minute highway cruise. On my highway cruise the A/F ratio fluctuates rapidly from rich to lean. Jeff said this is indicative of a primary 02 sensor going bad. I questioned why a 2007 with only 72k miles would have a failing 02 sensor and he said that the 02 sensor would actually continue to function for a long time, but if I wanted optimal highway fuel economy I would need a new sensor.

Performance of the car seems very good. A/F ratios under full throttle are at the correct level and stable.

So my question is, how many others have experienced this? How did you handle it? Will there be any performance implications if I don't replace the 02 sensor? So long as I have strong performance, I don't care as much about fuel economy. I don't drive my car a whole lot on the highway anyhow. When I do, I get around 26mpg highway, which is about right for an AP2. This leads me to believe the 02 sensor really isn't a huge deal for highway mileage either, but I'm not sure.

Thoughts?

 

Actually the OEM is a wideband, all you have to do is subtract 1. It's accurate enough.

deepbluejh, I suggest you check out the Hondata tuning forum. There is a notorious correlation between the flashpro and a primary O2 sensor failing. I don't think anyones ever proven the exact correlation, but there's a number of incidents that would indicate there's something going on.

Anyways, until it [if] it goes bad, you'll be fine. As long as it isn't affecting the timing at all, you really have nothing to worry about. If it does fail, it will affect your timing and this will be a big deal.

 

Yes there is, however my car is outside the VIN range for the inferior (failure prone) 02 sensors. It should have the updated 02 sensor. I haven't gotten a CEL since I started using the Flashpro either.

 

from what i read over the internet - fast fluctuation at closed loop is a sighn of a good O2 sensor.
slow AFR change is a sign of sensor getting old/bad.

i guess Jeff knows what he says - so so it's really interesting what happens here.

what's your AFR under partial throttle / cruising?
under WOT?

 

Partial throttle cruise is fluctuating between 14.0 and 15.5 mostly, with an occasional rich/lean spike. Is that normal? Full throttle pulls fluctuate between 12.5 and 13.0.

 

However I notice when I completely take my foot off the throttle, the ratio drops to nearly 30:1. I assume that's normal because there is no gas being injected into the cylinder. Is that correct? I'm a complete newbie to this.

 

i have the same problem and i got no cel either

 

Mine is the same but im a little more in the 15.5-16.5...and I see ~12.5-13.0 at around 6 to 2 Vacuum I haven't gone WOT or over 4K RPM's. Is this why I'm having this problem?
https://www.s2ki.com/...hpro-readiness/


BTW im running on a basemap to break in everything before the tune.

 

i'm not a a huge expert but from what i've seen it looks normal.

 

You guys shouldn't worry about fluctuations during a tune, only if it's reading like that after it's done... That's why you're getting tuned... is to get rid of those fluctuations...

And yes 30:1 would be indicative of fuel cutoff, which is normal.