Dyno tuning technique

[Cliff]

This thread is a spin off of the ECU thread to discuss the various dynotuning techniques that are possible. I'll start with the techniques I have I used.

 

When I did my first dyno session I only had open loop and the dyno's gas analyser. It was not a particularly successful run but was certainly educational.

 

The first problem I had was the dyno did not produce any power/torque values that where usable at the low RPMs. The bar graphics and numbers bounced all over the place in response to the twins firing. That left using the gas analyser. This also proved problematic as the sensor was put into the rear of the exhaust and the bend of the sports exhaust prevented this going in sufficiently. MAKE SURE the dyno you use has a sensor that will properly attach to the bike, ideally through the existing screws in the header.

 

The next time I went to the dyno I had the wideband sensor on the bike and the controller working closed loop. The technique I use runs vertically though the map ( constant speed ). I would have the operator maintain the speed of the dyno and then I would position the throttle to coincide with the throttle breakpoint. I wait for the close loop to settle, this took up to 10 seconds then as the map was way out, and then I would commit the adjustment and move on to the next throttle spot. After finishing all the throttle settings we move onto the next RPM and do the same.

 

Now my software is a lot smarter and I don't even need to wait for the closed loop to settle. I can set the throttle wait as little as 1 second then move on. The throttle is displayed on the bike's tacho for convenience. Any adjustment is automatocally applied if conditions are right ( a diverging correction factor ). A converging correction can not be used. A few passes are required to catch all the points.

It would be possible to run horizontally across the map. Set the throttle and allow a slow acceleration, then repeat a few times.

 

One thing to note is you can not get all the data points on a dyno. Only the top left half the map is doable. The bottom right of the map is not doable on a dyno. This is the back off /deacceleration area. I usually fill these on the road. This area might not sound important but it actually is if you want smooth throttle response for things like negotiating round abouts etc.

[dlaing]

I have noticed some Tuning Link runs result in ridiculous entries of like 2500RPM and wide open throttle.

So somehow or other, they are mapping at the lower end, atleast in terms of RPM...

I don't think theeese eeesse goooooooood for the motor gooozie.

Especially if it pings.

I am sure you ask the dyno dude(tte) not to bother mapping the lugging the engine range.

[jrt]

Why is it important to put the O2 sensor so close to the head? Is the O2 scavanged as it proceeds out the tailpipe, or is it just to eliminate any contribution from exhaust leaks downstream?

J

[Guest vkerrigan]

jrt.............They placed the sniffer for my tuning session through the right side muffler and into the crossover (Stucchi) as close to the meeting point of both pipes as possible.

He also had to use the ignition pick-up off the ECU rather than the plug wires to get stable and consistent readings. My map was set for a 13.0 A/F ratio throughout the entire rpm band and runs very well at those settings though fuel mileage took about a 2 mpg hit (now 38-40)...............vk

[dlaing]

Why is it important to put the O2 sensor so close to the head?  Is the O2 scavanged as it proceeds out the tailpipe, or is it just to eliminate any contribution from exhaust leaks downstream?

J

41495[/snapback]

I am not sure, but it may have to do with the temperature of the exhaust gasses.

PS "I am sure you ask the dyno dude(tte) not to bother mapping the lugging the engine range." should of read, "I am sure you may ask the dyno dude(tte) not to bother mapping the lugging the engine range."

[dlaing]

Or maybe threading in the O2 sensor is just a placebo for the inherent failure of O2 sensors to read the mixture accurately.

In any case, all the people who had great results with tuning link must indicate that it is accurate enough.

[moto]

Or maybe threading in the O2 sensor is just a placebo for the inherent failure of O2 sensors to read the mixture accurately.

In any case, all the people who had great results with tuning link must indicate that it is accurate enough.

41509[/snapback]

Are there really people who have had great results with a tuning link?

[jrt]

Of course- temperature of the probe. Gawd, I'm thick sometimes. The reversible reaction of oxygen with the zirconium working electrode is kinetically competent only at high T.

I think some of these probes get around that with an internal heating element.

Thanks,

Jason