GF07.61-P-3021V ME Flexible Fuel Vehicle (FFV), Function
GF07.61-P-3021V ME Flexible Fuel Vehicle (FFV), Function
- ENGINE 272.920 /940 in MODEL 203 as of 1.6.06 with CODE (494) USA version up to Model Year 8
75 Fuel tank
158 Catalytic converter
A1 Instrument cluster
B2/5 Hot film mass air flow sensor
B4/1 Left fuel level sensor
B4/2 Right fuel level sensor
B11/4 Coolant temperature sensor
B70 Crankshaft Hall sensor
G3/3 Left O2 sensor, before TWC
G3/4 Right O2 sensor upstream TWC
N3/10 ME control unit
N10/2 Rear SAM control unit with fuse and relay module
Y62 Fuel injection valves
If for example Ethanol was refueled, the mixture is at first too lean (oxygen sensor voltage jumps back to 0 Volt). The lambda control reacts if the mixture to be enriched until after fueling =1 is achieved again.
Corresponding to the Ethanol portion, the quantity injected must be increased, because Ethanol has a lower energy density than premium fuel.
The required factor is taught in as an Ethanol factor and is 1.0 for premium fuel and 1.43 for an Ethanol.
The Ethanol factor acts multiplicative on the quantity injected and leads to a self adaptation of the mixture formation. The Ethanol factor remains effective, until after the following fueling a new value is learned.
The determination of the Ethanol factor lasts approx. 8 minutes when engine is warm. Rough learning takes place in neutral. During the following drive precise learning takes place (prerequisite: engine load greater than 30% and rotational speed greater than 1400 rpm) .
FFV vehicles are equipped with the fuel injection and ignition system (ME9.7. The engine control unit for flexible-fuel vehicle vehicles has the following additional functions:
- Teach-in process to identify the fuel mixture in the fuel tank after fueling
- Ethanol factor from 1.0 to 1.43 for mixture adaptation
- Number of Ethanol teach-in processes - the value indicates how often a proportion of Ethanol greater than 30% was taught in.
- The message "last taught in Ethanol portion", indicates the proportion of Ethanol from the last conducted teach-in process. This value is irrespective from the Ethanol factor. If for example the Ethanol portion in the fuel tank is less than 18% the Ethanol factor remains 1.0.
- The message "Ethanol operation" indicates that the Ethanol portion in the fuel tank is more than 18%.
- The message "teach-in process" indicates that the teach-in process is active at this moment and the fuel mixture in the fuel tank is not yet identified. When the teach-in process is active, the mixture adaptation and the regeneration is locked.
- The message "exhalation procedure terminated" indicates, that the teach-in process is again released. During outgassing of Ethanol from the engine oil (engine oil temperature of about 40 to 85°C) the teach-in process is locked out. The ex halation procedure is only released, if beforehand a proportion of Ethanol of more than 60% was taught in.
Repair instructions for FFV vehicles
Before starting a repair it is necessary to read out the adaptation values of the mixture adaptation, the Ethanol factor, the last taught in Ethanol portion and the number of Ethanol teach-in procedures.
Example 1:
If during a repair the voltage supply to the engine control unit was interrupted, if the engine control unit was replaced or fuel refueled, afterwards release the learn mode with the STAR DIAGNOSIS.
Example 2:
If the number of Ethanol teach-in procedures is larger than zero and if a mixture adaptation is required after a repair, premium fuel should be refueled, so that the mixture adaptation can be conducted without Ethanol influence. After changing fuel, release the teach-in process with the STAR DIAGNOSIS.
When using premium fuel there is a guarantee, that for example faults due to unmetered air or a defective hot film mass air flow sensor are not learned (understood) as a proportion of Ethanol.
