Wideband AFR not matching DIYPNP AFR
 

Both items have good ground.
I called AEM and they told me for 31-4100 to input the following:
10.0 afr at 0.0V
19.98 afr at 4.99V

I took a video and the AFRs don't match.
It doesn't look like a delay either.
For example during the short video:
wideband vs laptop
15.2 vs 15.7
14.9 vs 15.5
14.5 vs 15.4
14.4 vs 15.0
14.2 vs 14.9
14.1 vs 14.7
14.2 vs 14.5
14.4 vs 14.7
14.7 vs 15.0
14.3 vs 15.1
14.3 vs 14.7

So it's not even a fixed pattern.
Any suggestions on what I can try?

you need to measure voltages to account for any groudning offset between the gauge and MS and account for that in the calibration, then if it's still not quite right...


you might need to change the lamdba lag factor? But keep in mind your MS will update the readings much faster that silly ass ugeo display will. it has awful refresh rates.

In general, what's a good lambda lag factor?

as high as possible (ie, no filtering/dampening).

To measure grounding offset. Do I do a voltage drop test?

Halcyon,
did you figure this out?
I am seeing a similar issue with my AEM.
Jim

Link your grounds.

calibrate your MS to match the actual output of you gauge, not the published settings.

Brain, is the assumption there that the gauge is right and the published settings become irrelevant once the grounding effects are factored in?

si.

does the aem let you output set voltages?

on my LC-1 i got it to output from 0v to 5v in steps of 0.5v and recorded what it gave me in tunerstudio. as well as a linear voltage offset that increased with voltage, i had a very funny point at the top end that was throwing my 0-5v calibration out using those two points.

https://www.miataturbo.net/attachmen...ine=1368544700

anyway, the upshot is, whatever afr (or volts) your tunerstudio reads for a given voltage output from your wideband, just set that afr as the setpoint for that voltage. in my case, 4.5v output gives 4.65v reading in TS... 4.65v = 19.33 AFR so set 19.33AFR to 4.5v in the wideband.

the check is to use the equation generated in the graph above to give you the offset for 14.7 AFR. For me, 2.265v output gives 2.35v reading in TS. Set output to 2.265v (an option whilst warming up on the LC-1) and check you get 14.7 AFR in TS.

however, if it's not a consistent relationship then you either need to work on your grounds or concentrate on the area from 11 - 18 AFR if that's any better.

I had to use the custom gauge for my AEM to match TS. The 4100 calibration was always about .15 to .2 off

iirc

0V = 10
5V = 18.7

I have a feeling that everyone may have a slightly different calibration due to grounding and wiring.

On AEM's site there is a post about this. They suggest disconnecting the sensor, turning the car on and seeing if the gauge and TS both show 14.7.

I did this test and they match perfectly. Once I plug the sensor in, the gauge shows 14.7, but TS shows 15.2.

Does this imply that it's an issue with ground differences, or a problem with the gauge/WB itself?

Is it possible that the increase in power consumption caused by the sensor being installed causes the delta?