AFR readings in old logs

Discussion of tuning specific to CX-7 vehicles
Post Reply
ozynigma
Posts: 3
Joined: May 30th, 2014, 5:40 am

AFR readings in old logs

Post by ozynigma »

Hi,

I have recently opened some of my old logs and my AFR numbers don't make sense.

For instance they are scaling between 153 and 430 in one old log.

My new logs are fine.

Is this a known issue and is there a scaling factor I can use in my spreadsheets to correct this to actual AFR?
User avatar
Ugnius @ VersaTune
Lead developer
Posts: 580
Joined: March 19th, 2010, 11:57 am

Re: AFR readings in old logs

Post by Ugnius @ VersaTune »

Please try changing the AFR measurement units to lambda in your settings, restart VT and check if the numbers make sense (1.0 is stoich, 0.8 rich). If they do, export the log to CSV and multiply the values by 14.7 to get the AFR values.

We previously had separate parameters for AFR measured in lambda and AFR expressed as the ratio (14.7:1). We merged those into a single configurable parameter in one of the recent versions.
ozynigma
Posts: 3
Joined: May 30th, 2014, 5:40 am

Re: AFR readings in old logs

Post by ozynigma »

Hi Ugnius,

That did not work. Settings were Lambda and I changed to AFR Gas and it made no difference to how the old logs displayed.

All my logs before the 1 Dec 2016 show the very high numbers. All my logs after that show AFR around 14 like they should.
User avatar
Ugnius @ VersaTune
Lead developer
Posts: 580
Joined: March 19th, 2010, 11:57 am

Re: AFR readings in old logs

Post by Ugnius @ VersaTune »

Could you please select those logs by marking the checkbox next to them, then click "Share Selected..." and email them to support [at] versatune.net
I will take a look at them.
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: AFR readings in old logs

Post by mituc »

It may not work on old logs. As far as I remember when I last looked the old .vtlog format logs either have AFR values or lambda values in, depending on what you logged.
If yours have AFR values in you will have to have the lambda option selected because this way the value will be multiplied by 1 which is what you want.
So take new logs :)
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
ozynigma
Posts: 3
Joined: May 30th, 2014, 5:40 am

Re: AFR readings in old logs

Post by ozynigma »

Solution seems to be divide by 14.7.

It's hard to redo logs from 2 years ago on a dyno before the engine was rebuilt. I just wanted to know how rich it was running back then. It's still got a rich running problem.
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: AFR readings in old logs

Post by mituc »

Post one of these new logs, and we'll try to help you out :)
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Post Reply