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The concept is fairly simple but not so easy to explain. I'll take a stab at it.

For an internal combustion engine to operate properly, it needs fuel and air in the correct proportions (air/fuel ratio). There's a theoretical ideal of ~14.7:1 called the stoichiometric ratio. This theoretically will allow each hydrocarbon molecule in the fuel to mate with an oxygen molecule and combust. Less air than stoichiometric is considered rich (i.e. excess fuel), more air is considered lean (i.e. excess oxygen).

Fuel injected engines control the amount of fuel entering the engine by varying the amount of time the injector nozzle (pintle) is held open (injection duration). Calculation are made based on throttle opening, engine RPM, temperature, barometric pressure and possibly other variables.

If we visualize this as a spreadsheet with throttle opening on one axis and rpm (for example - the other variables are also present) we can input a value where each cell intersects. This value represents injector opening duration. In essence, this is our "map". Throttle opening of "X" with RPM of "Y" equals injector opening duration.

Remapping is simply making an adjustment to these values. Most maps will show throttle opening in percentage such as 0, 2, 5, 10, 20, 40, 60, 80, 100. It is important to understand that the digital information we are creating in our spreadsheet "map" is really translated into an analog graph. in other words, changing a value at 60% throttle will affect the entire 40 to 80 percent range.

I hope this helps.
 

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I didn't delve into ignition mapping, but is the same idea. Find the ideal ignition timing point based on load factor. Load factor is a calculation of the same variables used to calculate injection duration.
 

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Mapping is quite simple in theory, not so in real life :ahhh: :stir:

The ecu reads all the engines inputs: rpm/air temp/water temp/air pressure/throttle opening, then cross references them to a fuel and ignition table within the ecu, (the map, or to alter the table would be "mapping the engine") it then says, or outputs "Right,I have looked at the "maps" and your having this much fuel per engine revolution (measured in milliseconds), and the spark here (measured in degrees)"

Easy eh? :naughty:
 

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Discussion Starter #5
Thanks that helps. Now who does remapping in southern calif. And knows what there doing. Also about the dyno in my experince a dyno only tells how how much hourspower a motor makes is this true or does it also help in mapping, tuning, airfuel ratio, etc.
 

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Discussion Starter #6
How is mapping done. Is it done to the Eprom or is there a computer that its done to.What does a lap top hook up to???????????????
 

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The map is contained in the EPROM. IMHO, a dyno is a necessity to get it right. For reasons that would result in a long winded post, it isn't possible to just attain a stoichiometric ratio and call it good. In fact, a stoichiometric ratio throughout the load range would result in burned pistons. By using a dyno the operator can see the results as tweaks to the map are made. Having said that, there are tuners out there with enough experience to tweak without a dyno, but unless you have much experience wiith the bike in question you're shooting in the dark.
 

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Discussion Starter #8
More Info On mapping a 910

How is mapping done. It is done to the Eprom or is there a computer on the bike. Where and what does a laptop hook up to.
 

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It can be done a few different ways. The most familiar is the Power Commander which connects into the Engine Control Module harness. The Power Commander alters the output from the ECM by changing the input values from various sensors.

Another method is to burn a new EPROM and replace the existing one on the board inside the ECM.

If you have the proper equipment, you can access the EPROM through the diagnostic port and re-write it.

All of these methods are proven to work, it is a matter of preference (and availability).
 

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Koop said:
The Power Commander alters the output from the ECM by changing the input values from various sensors.
Well, almost correct.

The Power Commander simply takes the fuel injector signal once it exits the ECU and alters it by either making the injector pulse longer (to richen the mixture) or shorter (to lean the mixture)

They do not "talk" to each other or interact in any way.
 

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I've bought an alternative mapping for my car and I found the explanation of the gain really helpful for the understanding of what you can have while remapping.
OEM mapping is made for an average engine (I don't think the difference between a good and a poor engine is very important but...) and an average fuel... This means, that for exemple in Europe, you can have your car running with high grade fuel in some countries (France, Italy, Germany, UK...) and lower grade one (don't have the exemples in mind...).
If you've got an alternative mapping, it is done for one kind of fuel (low or high grade, I suppose trere are not a lot of MV running with low grade...) so the engine may not run as well when using the low grade fuel.
Hope it helped.
Good rides!
 

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airfuel said:
Well, almost correct.

The Power Commander simply takes the fuel injector signal once it exits the ECU and alters it by either making the injector pulse longer (to richen the mixture) or shorter (to lean the mixture)

They do not "talk" to each other or interact in any way.
Hmmm...so the Power Commander doesn't alter ignition timing at all? The last Power Commander I used was in '02, maybe I mis-understood.

At any rate, I think the current Dynojet set up with a direct link from dyno to Power Commander is the way to go. You'll get a custom map tailored to your engine under all loads and it can even create a different map for individual cylinders.
 

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I've never understood mapping, and neither has my wife. Consequently, we often get lost, especially at foggy round-abouts. Now I know it wasn't her fault entirely, it was the injectors.
 

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Koop said:
Hmmm...so the Power Commander doesn't alter ignition timing at all? The last Power Commander I used was in '02, maybe I mis-understood.

At any rate, I think the current Dynojet set up with a direct link from dyno to Power Commander is the way to go. You'll get a custom map tailored to your engine under all loads and it can even create a different map for individual cylinders.

The older PCIIIr's did have the ability to alter timing on certain bikes, but the fueling changes were handled the same way.

The new USB PC's have ignition modules available for some bikes that can change ignition timing.

"Tuning Link" (what I use) can change the fueling map at every throttle position and every 250rpm. It takes very little time with this setup and I usually program 3 different A/F target ratios for light cruise, cruise and full power, Usually 13.0-13.8/1.
 

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Thanks for clearing that up. Tuning Link is the equipment I was referring to, it is probably the best solution available. Personally, I'd want to see 12.5/1 at wide open throttle just to be on the safe side of detonation.
 
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