Auto Tune, how does it work ?

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Dec 1, 2015 | 05:39 AM

#71

whittlebeast

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Dave, things are worse than even the graph you supplied. O2s are very sensitive to temperature on thee rich side of things. I simply assume when the voltage is above .45 volts, the AFR is richer than 14.7 AFR.

http://api.ning.com/files/0qkw8Ea4ZK...tage_vs_af.gif

Andy

Dec 1, 2015 | 05:42 AM

#72

Dave Cawley

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From: Dartmouth, Devon, UK

So then how does any Auto Tune accurately set rich AFR's as the map I showed ??

Dec 1, 2015 | 05:50 AM

#73

whittlebeast

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"Not well" if the bias voltage is away from .45 volts. They relay heavily on statistics and ignore the temperature thing. Heated O2 sensors helps things a little.

I don't do it.

Andy

Dec 1, 2015 | 05:54 AM

#74

Dave Cawley

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From: Dartmouth, Devon, UK

Thanks Andy, I think that proves my point. I have noticed "thread drift" and "confirmation bias" in this thread, to be expected, but I got there in in the end.

Many thanks

Dave

Dec 1, 2015 | 05:54 AM

#75

Notgrownup

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From: Snow Hill, NC

It didn't do **** for me, installed it and used it for a week and my mileage went to hell. Took it off and sold it...runs much better with my map from Fuelmoto. Many have great success with it, not me.

Dec 1, 2015 | 05:55 AM

#76

whittlebeast

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Once out of the closed loop area, they simply add 10% more duty cycle to what they learned chasing Stoich if they want 10% more Lambda.

You do realize that AFR target is in the fueling equation?

Andy

Dec 1, 2015 | 06:03 AM

#77

whittlebeast

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So your only purpose of this thread was to prove a "Tune Drift" point. We could of saved a lot of typing trying to teach how they work. The thread should have been titled "Is .8 volts valid and is there a down side to .8 volts?"

Dec 1, 2015 | 06:34 AM

#78

Dave Cawley

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From: Dartmouth, Devon, UK

Quote:

Originally Posted by whittlebeast

Not at all, but after a while it sort of became apparent, I then suggested it and a few disagreed. With your knowledge and experience I now fully understand that Auto Tune (and other names) on a standard Harley is far from perfect and I'll lower my expectations.

Many thanks Andy

Dave

Last edited by Dave Cawley; Dec 1, 2015 at 09:19 AM.

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Dec 1, 2015 | 08:56 AM

#79

JustDave13

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From: Somewhere SW

Quote:

Originally Posted by Notgrownup

It sounds like your other map was just set too rich.

Dec 1, 2015 | 09:39 AM

#80

fuelmoto

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From: Little Chute, WI

Quote:

Originally Posted by Dave Cawley

Bearing in mind Harley type Auto Tuners (and other names) are sold to be used with the stock o2 sensor, and a typical map may call for a lambda of 0.750, but the o2 sensor maxes out at 0.80 (or does it?), how do these manufacturers get that AFR let alone get the Auto Tune to work ? BTW I am very conversant with a lot of closed and open loop feedback systems, but not in regard to EFI applications.

Thanks

Dave

Typically for applications on the market that tune with factory NB O2 sensors during "auto tune" mode, the fuel table is changed to 1.0 Lambda/14.6 AFR and closed loop is commanded over the entire table. When gathering data once VE is established for a given target the ECM can do the math to delivery whatever is necessary (once the AF/Lambda table is changed back to normal). Essentially, once the ECM knows the VE to deliver 14.6 AF accurately (desired), in theory you can change the commanded AF and the mixure will follow. It all comes down to the accuracy of the data as well as the combination you are working with. There are several variations of this type of basic auto tune among products, it typically works very well for the closed loop region of the calibration where it is using very similar AF targets, the rest of the areas of the tune come down to calculation and accuracy.

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