Dyno tuning in a controlled environment is a must if you wish to get every last bit of power from your engine, but what about driveability and fuel economy?

Maximizing driveability and fuel economy requires that we do a fair amount of street/track testing. The is often the most tedious part of the tuning process.

Once again, Motec comes to the rescue with the incredible power of I2 Pro, and I2 Standard.

You can pour over the logged data meticulously extracting information and tuning your fuel curve, or you can just put it in closed loop, go for a drive/on track session and let I2 do the rest.

The best part of this approach is that the closed loop control keeps the engine running quite well while you are gathering the data needed for your fuel table corrections.

The first step is to turn off your long term filtering by setting the value to zero, and set large values for rich and lean trim limits. The next step is to set your ECU to log the Lambda short term trim values. The short term trim values are the amunt of fuel enrichment, or enleanment required to meet your lambda goal.

Now go into I2, open a new worksheet and add a scatter plot.

The following screen captures show how the parameters should be set.

Note that the min and max values for the Colour Channel are quite large. Your first reaction is probably that you couldn't possibly have any errors that large in your tune. You may be right, but it is quite simple to narrow this range as the tuning progresses, and in fact this range should be narrowed as gross fuelling errors are eliminated, and you start to dial in on optimum.

Ultimately the min and max values should be set to -5/5 which will show 1% resolution to allow for very accurate tuning. Additionally, once the air fuel ratios are dialed in within that range, you can set the rich and lean trim limits to -5/5 or even less so that you will not be caught out by a bad Lambda sensor.

The final screen capture shows a scatter plot for a car that has seen nearly zero tuning, and some gross fuelling errors are obvious.

To make corrections, you simply make the required percent correction on the appropriate cell in the fuel table. For instance, at 75% Efficiency, and 3500 RPM the short term trim is a whopping 27%. Select that cell from your main fuel table, and then enter "1.27*" which will increase the value by 27%. Had the trim been -27%, you would take the value 1.27 and divide that into 1 which gives you .79. Enter ".79*" and the value will be decreased by 27%.

The advantage of this type of tuning is that the closed loop control makes the fuelling errors much less problematic while the car is on the street/track, acceleration fuelling is automatically eliminated from the picture, and we still know the error values so that we can make corrections.

Once again we see how the superiority of Motec Engine Management simplifies the tuning process!

Happy tuning.

Paul Yaw

Yaw Power Products