Auto Tune, how does it work ?

OK, so we all believe Harley tune on the lean side. So you get a tuner and on a simple Stage 1 the AFR tables are richer. Job done, or is it ?

So Auto Tune :

What does it do ?

What does it alter ?

How/what does it sense/detect, so that it makes the changes ?

In other words, if at a point the AFR was 14.6 and the new map is 14.3, doesn't that tell the ECU what to do ?

What is the Auto Tuner actually doing then ? Is it altering the map ? If so on what sensed information ? and why ?

I'm looking for a detailed explanation please ?

Thanks

Dave

 

Maybe ???
http://dynojet.com/powervision/power...e-details.aspx

 

That's a good description.

Here are the tech cliff notes.

Auto tune basic sets the fuel at at 14.7 and uses the stock 02 sensors for feedback (like closed loop).

What it simply does is add or take away fuel until it reaches the desired 14.7, then using injector pulse time the software calculates how much air your engine is passing at that given moment. (this is why you want to hit as many cells as possible)
This is how it figures the VE ratios (how much your engine breathes) which are the most important numbers for setting up an accurate tune.
Without accurate VE numbers as a foundation your tune will be off.

IIRC the only thing it can and does alter are the VE ratios.
From what I understand the older versions could be 'hacked' to do other things.

BTW VE=Volumetric Efficiency, it's how much air your engine can move. It's effected by cams, displacement, intake, exhaust and head work.

 

OK thanks guys, but if the ECU knows from the Map that say an AFR of 14.3 is asked for, so why doesn't the ECU adjust VE to achieve it ?

Why else would there be a Map with 14.3 ?

 

14.3 would be the target ratio for that cell, the changes and adjustments are made on the fuel side rather than the VEs.
Even though the ECU will make minor changes to the VEs it (ecu) looks at the fuel map to see what it wants at any given time.

So if you have 14.3 the ECU sees that and based on the VE numbers for that cell the ECU know exactly how long to keep the injector open to achieve the 14.3 afr.

In closed loop the ECU will look at the 02 sensor for confirmation and make any adjustments that may be needed.
In open loop the ECU is completely relying on the VE numbers to deliver an accurate afr

I think they have a new setup for the Power Vision where it will change VEs in real time. it's called Target Tune http://www.dynojet.com/powervision/

 

OK, but the Auto Tune must be able to recognize 14.3 from the O2, so why doesn't the ECU and adjust appropriately? Or in other words, why no closed loop on say 14.3 ?

Confused

Dave

 

On my tune the closed loop range is from 14.2-15.0 so it should recognize 14.3, even for narrow band sensors that's within range.

What would make you think it isn't operating in closed loop at 14.3?
Edit...Stock auto tune using the narrow band factory 02 sensors sets the afr 14.7 across the board. This is where the 02s are most accurate.

After you're done auto tuning (assuming you're using a basic auto tune feature) you save those final VE's to your tune.
You only run 2 or 3 auto tune sessions then save the results.

What kind of tuner are you using?

Here's how I do mine.

 

Just installed target tune and believe that this is closed loop like the stock but with wide band 02 sensors. Have yet to auto tune but will do so soon.

 

I was thinking about getting that but I don't know if it would be worth it.
You're right, they have Bosch wide band sensors that cover a lot more area than stock narrow band sensors.

 

What would make you think it isn't operating in closed loop at 14.3?

Because if it was, the ECU would adjust the VE and make any Auto Tune redundant ?