AFR MAPS

[Tordne]

:oops: I'm embarrassed to ask, cause I am sure this should be obvious :oops:

When using the commanded and WB02 AFR MAPS should the values be viewed as Min/Avg or Max?

Cheers :oops:

[SinisterSS]

For my WBO2 logging, I use the average values for measured AFR.

[Tordne]

Thanks for that. I just wasn't sure, and there is obviously a slight difference in the values.

I have a bit of KR which I am trying to get rid of, so now its into the loged data.

Cheers.

[Tordne]

I've just gone and logged a run so that I can look at getting some of my calibrations better, and noticed the following which I just want to clarify.

I have some AFR MAP cells that have a MAX of 19.57, where as the AVG in the same cell is 15.2.

There is quite a large gap between these values, is it still best to use the AVG number?

I know these numbers are terrible, I have just been making some major changes, and trying to get my head around the relationships between different parts of the calibrations. If it isn't obvious already, I an an extreme 'newbie' to tuning!

Thanks for your help.

[SinisterSS]

Are those 19.57-ish values at low manifold pressures? It may be DFCO causing the lean values.

[Tordne]

Hi Rick,

The 19.57 values are in the 15-35 kPa ranges.

Could the Spark or VE tables also be causing this? Basically what I did was take a OS from a car (HSV GTS) which is MAFless (I have the Commercial version). Apparently this vehicle also has a bigger cam. The VE table is quite different, and the Spark tables generally have higher values than my previous tune.

It might have to take a visit to a professional, am really pleased with the responsiveness of the car though being MAFless, seem to be a huge difference.

Thanks very much.

[Tordne]

Should DFCO lean out the AFR's this much (around 19.5:1)?

[Dirk Diggler]

Yup it cuts off the injectors. at that point its pumping air

[Tordne]

And this can't cause any problem/damage with the AFR's at above 19:1?

These numbers skew the averages when trying to adjust your VE table. I guess that is perhaps why it is desirable to use the bi-firectional controls to force a AFR ration of around 13:1.

Cheers.

[Dirk Diggler]

And this can't cause any problem/damage with the AFR's at above 19:1?

These numbers skew the averages when trying to adjust your VE table. I guess that is perhaps why it is desirable to use the bi-firectional controls to force a AFR ration of around 13:1.

Cheers.

Disable DFCo so it wont do that. that is what i did for my mafless tune. No it wont cause any problems. There isnt enough air and the injectors are being cut fully(you can see this if you look at IPW). You cant combust air by itself so the enigne is just pumping air at that point