This function is used to program the calculated ethanol content.
Some troubleshooting/actions require that the vehicle's calculated ethanol content matches the fuel's true ethanol content. Deviation may lead to subsequent damage and generation of error codes. If the match is within 5 percent, it is considered approved.
The fuel's ethanol content can be decided by:
Asking the customer what the car has been refuelled with the last few times.
Measuring ethanol content, acc. to the method below:
The method works for gasoline-ethanol fuel: Mix equal parts water and fuel in a graduated, transparent container. Let stand for 5 minutes. The ethanol dissolves in the water, and the mixture is layered; gasoline is lightest and ends up at the top. Read off the number of graduation steps for gasoline, and compare to the number of graduation steps for fuel that was added. Best accuracy is achieved with a tall-narrow measuring glass. Suitable volume is 0.5 - 1 litre.
Example: Mix 0.5 litre fuel with 0.5 litre water. After the ethanol has dissolved, say that the amount of fuel is measured to 0.1 litre. Then the ethanol content is calculated to: (0.5-0.1)/0.5 = 0.8 = 80%.
Changing to known fuel mixture.
E85-fuel normally varies between approx. 75% ethanol (winter) and 85% ethanol (summer). Also, "pure" gasoline normally contains some ethanol (presently 5% in Europe).
Note:
If possible, avoid opening the tank hatch before adjusting the ethanol content, since this means risking losing the new value. If the tank hatch has been opened, make sure that the engine has been running for at least two minutes and that the vehicle has reached a speed of at least 50 km/h before programming takes place.
Test conditions:
Ignition on, engine off.
Tank hatch closed.
Procedure:
Select the function "Programming ethanol level", press "OK"
A dialogue box with programmed ethanol content is shown.
Press "OK" to continue.
Enter calculated ethanol content and press "OK" to start programming.
Programmed value is shown after successful programming.
Press "OK" to exit the function.