stock AFR vs AEM ugeo

[arcsnsparks]

hello all

 

so i was emailing with my tuner about getting my in dash AEM wide band integrated into the AP for logging purposes.

 

also asked why the AEM and the AP readouts generally agree with each other....but the AEM shows AFRs going lean near redline 13:1ish while the AP stays 11:1ish

 

the tuner says:

Can't speak to discrepancies without actually diagnosing it. Usually an air leak or installation thing with the aftermarket sensors. They're highly sensitive to that.

 

he told me that since he cannot verify the install of the bosch sensor i put in the down pipe. he cant determine which one of them is more accurate.

 

said that the stock sensor in the up pipe is a wideband.... at one point goes on to say that he used a dyno AFR sensor when he tuned the car about two years ago because the stock AFR is not accurate for open loop fuelling.

if it is a true wideband then why did he need to use a diffrent one for open loop?

 

i did a fair amount of reading on AFR and O2 sensor tech.....learned about a nernst cell, planar design, zirconium dioxide then i looked at Denso's site and............ i still don't know what kind of cell a oem Denso uses

 

does anybody know what cell the oem Denso AFR sensor uses?

 

thanks in advance!

[mwiener2]

You're gonna get a lot of mixed information on this one...

 

In general, the stock front oxygen sensor is considered a narrowband sensor. It outputs a 0-1 volt signal to the ECU and is most accurate between 13:1 and 15:1 AFR's.

Most professional dyno tuners would not rely on the this sensor for tuning. Many E-tuners DO rely on these sensors. This is a topic of debate.

 

The AEM sensor is a true wideband with a 0-5v volt output and is accurate between 8:1 and 20:1 AFR's

 

 

The difference in readings you are getting between the two sensors is a possible cause for concern. The discrepancy could be caused by a sensor calibration issue, a failing sensor, an exhaust leak, or an actual tune issue.

If the two sensors agree most of the time, but not under certain conditions, I would suspect a leak of some kind.

[Infosecdad]

From my research and work in this space there are a number of variables.

 

The front O2 sensor is technically a wideband. But there are two caveats. First, it's in the wrong place to use as a wideband for tuning, it's down in the manifold/header; I usually see recommendations for a little behind the turbo for tuning. Second, it has a relatively narrow range for a wideband. And doesn't really go below 11.1 or so.

 

I have both the stock front O2 and a AEGO in a downpipe bung. They are fairly close to each other most of the time, difference in the midrange is largely due to the location. I did find that I had a broken weld on my up-pipe because there was a noticeable difference in their readings about 3 months ago.

 

If you have that big of a difference between them, I would wonder if you had something similar and have a gasket or weld leaking around the up-pipe/turbo.