EFILive Guys - get rid of incorrect WB AFR PIDs (as they assume E0 fuel)

[Mr. P.]

I switched widebands this last week, going from a PLX to a NGK AFX (sweet unit, love it) and when I looked closely in EFILive at the wide band PIDs, I discovered that all these are assuming the fuel in the vehicle is 14.7:1 stoich, and that assumption will give incorrect results/logging for most users - the reason why is the increased sale/distribution of E10 in place of 'real' gasoline E0; by 2012 all US gasoline pumps will be E10 due to laws passed by the Obama administration several years ago.

In detail - take a look at the "Wide Band AFR 1 - NGK AFX" PID (CALC.AFR_NGK1), the formula/expression for it is revealed as: AFR = {EXT.AD1} * 1.4 + 9; this math will return the correct AFR if the motor happens to be consuming/exhausting E0 gasoline - this is only accurate for a decreasingly small part of the US population because most heavily populated areas are required to sell E6, E8, or E10 in place of gasoline. In the case you are using E10, the equation for this PID will be {EXT.AD1} * .735 + 8.79 (approximately, assuming stoich of 14.17:1).

I am suggesting to the EFILive developers, either:

1) update the AFR PIDs so that they use some user-input variable stoich value (the same way you have a user give the assumed charge temp for VE grams/cyl calculations in EFILive Tune V7.5 -> Edit -> Properties -> Display folder tab)
- or -
2) remove these PIDs completely, as they are often increasingly incorrect, and unreliable for tuning -plus- best practice now is to monitor EQR or Lambda and determine BENs from the Lambda reported by the wideband device.

Personally I suggest option #2, and get away from using or promoting AFR all-together, and force users to make a calculated PID if they really want to go to the effort to display AFR.

Mr. P. :)

[joecar]

Probably the tutorials should be re-written to use Lambda and EQR (and the serial comms versions of those).

[GMPX]

How do you know what the ethanol content of the fuel is? E85 for example can vary greatly, is E10 really E10 on every tanker fill? Or maybe E6, E8?
If we remove the PID's we'll forward all complaints to mrp@ :sly:

[mr.prick]

The AFR pids are written to match the WBO2 manufacturer's definition of stoich AFR.

Lambda can easily be added by EFILive though. :sneaky:
IMO the BEN factor pids should definitely be re-written.

There is thread somewhere around here that explains how match
the PCM's stoich AFR value to WBO2 analog output.
:angel_innocent:

[redhardsupra]

In the long term use lambda, just like Banish has always preached. In the short term, make a custom pid that 'wraps' the official WB pid and gets it to reflect the real AFR.

And as far as batches of fuel go, I've seen E-10 to be closer to E-20 on multiple occasions already :/ so don't replace one assumption (gasoline is E-0) with another assumption (gasoline is E-10), when reality is a bit more varied than that.

[ScarabEpic22]

Ugh seriously? Im hoping the gasohol around me is E6-10, looks like I need to buy a test kit. E10 is horrible already, wreaks havoc on marine fuel systems especially older systems that arent designed for it and breaks junk loose in the fuel tank. E20 will be a nightmare.

[Mr. P.]

...If we remove the PID's we'll forward all complaints to mrp@ :sly:
:doh2: I guess that's what I get for opening my big mouth! :grin:


Probably the tutorials should be re-written to use Lambda and EQR (and the serial comms versions of those).
DEFINITELY.


The AFR pids are written to match the WBO2 manufacturer's definition of stoich AFR...
Oh trust me I've gotta bone to pick with all those WB manufacturers as well, they need to quit displaying AFR on gauges and instead display Lambda; my brand new NGK wideband I just permanently mounted in the glovebox because the AFR display, while being very sexy, is also very incorrect. Equipment like this in the hands of the uneducated leads to grenaded motors.


Ugh seriously? ... E10 is horrible already ... E20 will be a nightmare.You're preaching to the choir - there's lots to hate about that stuff, both technical as well as political and financial. But the law is already passed, and the transition to gasohol is already largely complete in this nation. :(

Mr. P.