AFR differences dyno/K-Pro

RiC · Post by **RiC** » Sat Aug 30, 2008 12:32 pm

Went to the dyno but the AFR readings from the Dyno and the K-pro was different, the K-Pro reads about 0.6-0.7 richer than the Dyno's AFR, the Dyno is a Dynojet. Which AFR should I obey?

fonz600 · Post by **fonz600** » Sun Aug 31, 2008 1:53 am

I got that as well mate but I'm supercharged and my KPro AF and my AEM AEGO gave the same values at WOT but the one at the dyno sometimes showed up to 2.0 difference which had me worried as was showing 13 odds sometimes was is lean for a charged car.

I went with the Dyno one as would rather it was richer if the dyno was wrong than run lean and believe the OEM sensor.

Wouldn't mind an answer from Hondata on this though.

Mine was on a Dastek Dyno but believe the AFR sensor is a seperate entity to the dyno.

TTR · Post by **TTR** » Mon Sep 01, 2008 9:56 am

Where was the dyno wideband positioned? In the manifold or at the exit of the exhaust? All of the dyno widebands I have used give lazy readings and are usually lean compared to a sensor in the manifold. I NEVER use a tailpipe wideband to tune a car. I would trust the K-Pro before a dyno wideband any day.

fonz600 · Post by **fonz600** » Mon Sep 01, 2008 5:31 pm

Tailpipe for me but the Dyno operator is a personal friend and also the guy who wrote the software for it.
He swears by the probe.
Just wondered what Hondata think.
I'm Supercharged so work towards the limits of the OEM sensor.

Post by **Spunkster** » Wed Sep 03, 2008 10:32 am

A wideband in the tailpipe will always read leaner than in the manifold. It will also read leaner if there is a cat.

carbonctr · Post by **carbonctr** » Wed Sep 03, 2008 11:43 pm

I have a UK Civic Type-R, JRSC, Mugen Header with cat. The car was dyno tuned with the cat in place using a tailpipe probe. Later, I added an aftermarket wideband for AFR info. When the wideband was in the primary location the target and actual AFR were very similar. Now I have the wideband in the secondary location after the cat and the AFR's are still very similar. eg, when in closed loop the target and actual AFR are pretty much bang on 14.7
I'll add a couple of datalogs to this post when I get to my work..... done...you will need to enter the following conversion table under settings/wideband input:
o2 sensor voltage AFR
1.333 7.350
1.958 10.358
2.681 13.366
3.413 16.374
4.145 19.382
4.853 22.390
4.9946 22.9916

These datalogs were taken at different times with a change of spark plugs between them but it gives a rough idea of similarities in AFR between the 2 sensor positions.