An Analysis of a Power Commander Map - Motorcycle-Journal Forums

nicocorea · 05-28-2008, 11:25 AM

Folks. I received my power commander last night and had a wonderful time installing it--really, it was a breeze. I fired the bike up and revved it a few times. Maybe it's just my imagination, but it sounded better somehow. Next I plugged my laptop (with the power commander software running) into the power commander unit and fired the bike up. I saw a wealth of data on my laptop screen that I only dreamed of before! I've already rearranged my wish list to put the power commander display up at the very top!

So far I've only had a chance to ride to work, and that's only a mile and I don't get out of third gear. But at lunch I'm going for a nice ride on HWY 66 where I can really open it up.

My power commander came pre-loaded with a map that's specifically designed for a completely stock VZ800 with debaffled pipes. Believe it or not, there's such a map out there.

A "map" is just a table of numbers that you load into the power commander, which it uses to decide, given engine speed and throttle position, how much fuel to add or subtract from the stock mixture.

But a bunch of numbers in a table is hard to make sense of until you make a picture of it. So I made one. That picture is below. (I simply took the preloaded map from my power commander and graphed it).

The X-axis indicates how much you're twisting the throttle. 0 is no twist, 100 is full throttle. The Y-axis is engine speed in RPM. At any RPM and throttle position combination, the colors indicate how much fuel the power commander adds or subtracts to/from the stock air-fuel mixture. Green shades represent an increase in amount of fuel over the stock amount, and blue shades represent a decrease in the amount of fuel.

For example, at 1500 RPM with 50% throttle, the power commander is reducing the amount of fuel in the mixture entering the cylinders by 15 to 20 percent from the stock mixture. But at 4500 RPM with 50% throttle, it is increasing the amount of fuel in the mixture entering the cylinders by 15 to 20 percent from the stock mixture.

Suppose you're acellerating at full throttle. Between 1000 and 3000 RPM, the power commander is leaning the mixture substantially, by about 15-25 percent. Between 3000 and 5000 RPM it is enriching it slightly, between 0 and 10%. And once you approach redline, it leans it between 5 and 15%.

But we don't accellerate at full throttle often. I'd say we spend the vast majority of the time with the throttle between 5 and 25% open with engine speeds between 2500 and 4000 RPM. In this area of the graph, you see that the mixture is almost always being enriched a moderate amount (10-15%), but sometimes over 20%.

It's interesting that in the typical use region, the mixture mostly being enriched. But at the edges of the envelope, substantial leaning is required to get the most out of our powerplants. I suppose that's why some of the cheaper fuel processors only have the capability to enrich the mixture--that's simply what's called for in the most typical riding situations...

Anyway, I figured some of you might be interested in this. I find such things completely fascinating.