Monday, October 8, 2012

Tuning: AEM FIC Calibration

The AEM FIC is installed, software and firmware updated and I've updated the fuel map! Now onto calibration! The FIC will have all the appropriate signals from the factory computer, but it has no reference point. By calibrating the FIC, it provides confidence that at a specific signal level from the sensors provide an expected observed output (to a precise degree).

You'll know that you haven't calibrated the FIC if the highlighted cell (when the car is running and the gauges window is up in the AEM FIC tuning software) in the RPM range does not correspond to the actual RPM range as read on the car's gauge. e.g. the car is idling at 800 RPM but on the FIC tuning software, the cell highlighted is 1200 RPM. The FIC doesn't know what signal level corresponds to what RPM.

To calibrate the FIC simply follow the user manual and follow the prompts on the screen. Ensure that your map is opened and the computer connected to the FIC installed in your car. To open the calibration, go to the 'Setup' menu and select 'Calibration'.

In the 'Calibration' menu, do the Throttle Position Sensor (TPS) calibration first as it's the easiest! First, have the car turned OFF then click the 'Auto' button in the 'TPS' section. Follow the prompts by having the first reading with your foot OFF the accelerator pedal, then your foot pushing the pedal down as far as it can go. That'll give the FIC the 0% and 100% TPS levels. The TPS signal is a load signal used not only by the factory ECU but the FIC. It shows how much the throttle is open hence how hard the accelerator pedal is being pressed.

Now to calibrate RPM, you'll need to start the car. Once the car is idling, in the 'Calibration' menu, enter a low RPM, for example, 2000 RPM, then click 'Auto'. Follow the prompts by reving and holding the engine at the selected RPM. If you select a high RPM, it's more cumbersome to hold (e.g. 5000 RPM), which in turn could give you an inaccurate calibration. The FIC needs this to correclty determine RPM from the signal inputs (e.g. from the CAM and Crank sensors) of the factory ECU.

Nice! The FIC is now calibrated. After running the car for a bit, the fuel trims on my ScanGauge didn't fluctuate too much:

Long Term Fuel Trim (LTFT): 8
Short Term Fuel Trim (STFL): (stable)

This means, the engine is running a bit lean and the factory ECU is compensating by adding a bit more fuel (LTFT = 8). STFL is quite stable, fluctuating from -3 to about 4, which is normal as the factory ECU compensates for the changes in environment as the car drives and heats up. Fuel Trims will be talked about in another post!

Not bad! The FIC is working correctly! The injector re-size adjustment I did early turned out a treat! The car is pretty much driveable at this point.

So time to go for a spin and gather some 'Stock' data! I went for a drive and logged some data using the FIC's data logging capabilities. You'll need to have a laptop connected to the FIC though or you can use the internal data logging but there are some minor draw backs (refer to the manual).

It's important to log stock data as you'll have a baseline to compare you new turbo tune against. If something behaves weirdly later on, you can check the behaviour of that item in the logs and see whether your mod affected the item's signal. Try to log a variety of driving situations, like stop and go, slow acceleration, fast acceleration, full throttle, partial throttle etc. I'll talk about data logs in a future post!

The FIC is now all done!

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