Engineers: Do We All Need Autotune?

Today I talked with a technical assistance gentleman at Dynojet about Autotune. This is what he told me was the main benefit of Autotune: The EPA restricts the reading range of O2 sensors in the exhausts on stock motorcycles. For example, Harley's O2 sensors (and he assumes Rockets are the same) can only read AFR's between 14.3:1 and 15.2: 1. Any system relying on input from such a restricted O2 sensor will never know if the actual AFR being produced is outside those parameters so it obviously cannot correct to an AFR outside those parameters. For example, if you want an AFR of 12.8:1 at 3,000 rpm's and your system is using an EPA restricted O2 sensor your system will never be able to detect AFR's below 14.3 so it cannot correct your actual AFR to 12.8. Autotune includes an O2 sensor that is not EPA restricted and it can read AFR's in the exhaust from 10.0 to 18.0, so it can detect actual AFR's below 14.3:1 and thereby enable your bike to correct its AFR to 12.8. He also told me that Tunecu employs the stock O2 sensor so it, like stock bikes, is "blind" to anything below 14.3:1.

Don't raise hell with me over this. I am just conveying what the man told me.

it reminds me of the 85 miles per hour speedometers of the eighties. If you decide that you want to go faster than 85 you don't have any business knowing how fast your going.

that 85 miles per hour maximum on the spedometer was a US mandated law so I don't know if you guys from across the pond had the same dilemma that we did.

SOUNDS LIKE THE AUTO tune is more accurate on the o2. the stock sensor tries to bring the fuel mixture back to a mid position (for example if it goes out of range to rich the comp leans it till it is to lean) with a good sensor it changes rich lean rich lean real quick.
i think that in the end fuel and timing is what the computer controls to make it run. very basic you want it to work they way you drive and you have not given info on that. have you remove the cats to much gas will effect them.
i guess what i am saying is your tuner should gather all the info (driver habits and bike info) and then advise you.

Simply the OEM O2 sensor is a simple and fairly cheap NARROW BAND sensor. It assumes the ECU tune is more or less correctly tuned and that the vehicle is stock. It is also very emission control biased - in fact that's most likely it's real reason for fitment - law compliance. It's there to make slow changes for changes in mix caused by ambient temp/pressure shifts and fuel octane changes.

Adding a PCV (or Dobeck etc) basically bypasses the ECU signals to the injectors. Adding or subtracting duration based on what you tell it to do.
The Stock Sensor should be removed if you add a PCV. End of Story. The PCV comes with the bits to do this.

The PCV AT sensor is CONSUMER GRADE WIDE BAND unit. But it's NOT a fully calibrated WIDEBAND as used by professional tuners - One of those sensors costs more than a PCV. I've heard of Dynos centres that change the sensor daily.

It is however (as IDK says) the solution for anybody who cannot get to a good Dyno tuner. This includes me.

However to get the AT (or any other piggy back system) to work correctly you MUST make some changes in the stock ECU. One especially relevant on the R3 is the F->L switch value.

Quite how you do this depends on how you ride - and I'd suggest a bit of data collection using something like the app "Torque" as a precursor to tuning. The AT is a tuning AID. It cannot read minds.

And I'd add that the PCV tunes that Dynojet supply are CRAP. Thank God for Hanso.

Once the AT is only making tiny changes day to day - frankly you can apply the trims to tha base PCV tune and remove the AT setup. The PCV will have a good solid map for YOUR bike and YOU riding it.

I'll have to send you my new map once I get a couple of flat spots out of it, come out a tight round about in second gear yesterday and just powering on as I changed direction from leant over right to lean over left the front started to lift .... Gave me a bit of a heart starter as I was not expecting it, I will send it once I get the last little bit right I'll be call it V2.5 and will suit the lower gears better than V3 as I fond it a bit to rich

HansO said:

I'll have to send you my new map once I get a couple of flat spots out of it, come out a tight round about in second gear yesterday and just powering on as I changed direction from leant over right to lean over left the front started to lift .... Gave me a bit of a heart starter as I was not expecting it, I will send it once I get the last little bit right I'll be call it V2.5 and will suit the lower gears better than V3 as I fond it a bit to rich

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Hanso, would V2.5 work well in a Touring with Jardines and stock air filter? I have a PC5.

It will work well on any model as long as you also are running an Auto Tune. My maps are a set of AFR values for the Auto Tune and PCV to follow

HansO said:

It will work well on any model as long as you also are running an Auto Tune

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Then Autotune it will be!

forklift said:

that 85 miles per hour maximum on the spedometer was a US mandated law so I don't know if you guys from across the pond had the same dilemma that we did.

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Thats right there is no reason to go over 85 mph