Engine variant for E85 fuel
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Engine variant for E85 fuel
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Engine variant for E85 fuel
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The engine variants are adapted for driving on the E85 fuel type which is a mixture of ethanol and petrol. Ethanol is an environmentally-friendly fuel as it does not add new carbon dioxide to the cycle when combusted.
E85 is a mixture of 15% petrol and 85% ethanol. Ethanol has the formula C2H5OH and accordingly differs from petrol as it is
one
substance and not a mixture of several.
E85 has the following properties that distinguish it from pure petrol:
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Lambda 1 at 9.8:1 instead of 14.7:1.
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Worse evaporation at low temperature.
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Higher octane rating (104 RON).
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Colder exhaust due to greater fuel mass at Lambda 1.
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Better fuel-air mixture cooling during evaporation.
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More aggressive against certain metals and plastic/rubber.
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Lambda 1 at 9.8:1 instead of 14.7:1
The engine can be run on all fuel mixtures from pure petrol to pure E85. This means that T8 must learn the mixture to be able to calculate the correct injection quantity. The adaptation is conducted by examining the lambda control. If the vehicle is run on pure petrol and then refuelled full with E85, then the lambda control factor is increased because oxygen sensor 1 shows lean with the new leaner fuel. During E85 adaptation the lambda control factor is seen to increase, so we decrease the recalculation factor from 14.7 to a lower value, (minimum 9.8 with pure E85) and increase the injection times in this way until the lambda control works at around 0% again.
The E85 adaptation can be seen as a variant of the traditional multiplicative adaptation. The E85 adaptation does not take place continuously but only if refuelling has been detected.
It is therefore very important that the engine is run until it is warm (however at least 5 minutes) following refuelling with another fuel, so that an adaptation is completed. Driving should be calm (lambda controlled). If consideration is not made of this a subsequent cold start could be difficult due to incorrect adaptation.
Hard driving (not lambda controlled) directly after refuelling with another fuel could lead to engine damage as T8 would then adapt fuel quantity and ignition timing according to the incorrect fuel.
Adaptation takes place when one of the following as occurred:
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When refuelling has been detected in one of the following ways:
- The level in the tank is higher than when the ignition was last turned off.
- The level in the tank rises when the car has been stationary for more than 11/2 minute with ignition turned on.
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The level in the tank is below 8 litres and lambda control is outside +/- 10%.
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If the previous adaptation was discontinued before it was complete due to the ignition being turned off.
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Following loss off power supply +30 to T7
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Following clearing of certain diagnostic trouble codes.
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On command from Tech 2.
The adaptation value is saved in the flash memory for 15 minutes after the ignition has been turned off. This means that refuelling with another fuel followed directly by battery replacement within 15 minutes leads to incorrect adaptation values being used at the next start, which could lead to starting problems. However, after the engine has started running, an adaptation will take place as the +30 power supply has been lost.
Examples that lead to incorrect adaptation value:
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Driving too briefly following refuelling with another fuel (cold engine or less than 5 minutes with warm)
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Driving too hard following refuelling with another fuel (not lambda controlled)
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Replacement of tank contents (draining 20 litres of E85 and filling 20 litres petrol, e.g. in connection with pump or tank replacement)
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Fault in component, e.g. fuel level sensor, oxygen sensor 1 (before catalytic converter), mass air flow sensor or fuel pump
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Air leakage in the induction system
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Loss of +30 before adaptation or writing to flash memory has taken place
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SPS programming (overwriting flash memory) without re-entering the original value following programming
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Worse evaporation at low temperature
Starting characteristics in cold are limited by the E85 content in the fuel. Almost no ethanol is evaporated at temperatures below 40 °C. Starting at lower temperatures is made possible by means of the proportion of petrol in E85 (15%). When driving on pure E85 the car starts to become difficult to start at approx. -15 °C. Any restarts are normally without problem as ethanol does not form soot on, or acidicly degrade spark plugs as petrol does. At temperatures lower than -12 °C an engine block heater should be used when the car is parked for a longer period. A greater proportion of petrol in the tank is recommended during extreme cold and uncertainty over access to engine block heater sockets. A fuel driven engine block heater must not be installed in E85 cars. The starting fuel quantity and post-start enrichment is considerably greater with high adapted ethanol content. This means that engine oil dilution is greater than during operation on pure petrol. This is one of the reasons why the service interval for BioPower is shorter.
Due to ethanol's poor evaporation in the cold, misfiring may occur with a high engine load and cold engine. For this reason, an engine temperature dependent torque limitation has been added. The limitation is active at 50-85% ethanol in the fuel and an engine temperature lower than 50 °C.
Higher octane rating (104 RON)
Ethanol's favourable effect on the octane rating enables higher engine torque and output. Max. torque limitation in the T8 is steplessly dependent on adapted ethanol content.
This means that the car may seem sluggish after driving on E85 for a while and then changing over to petrol.
Faster combustion
Ethanol provides faster burn-through of the fuel-air mixture after the spark plug has ignited. This means later ignition is selected when the ethanol content is great. Similarly for torque limitation, the ignition timing depends on adapted ethanol content and is changed steplessly from the best angle at 0% ethanol to the best angle at 85% (pure E85).
Colder exhaust due to greater fuel quantity with Lambda 1
The effect of the greater fuel quantity is that the exhaust gases are colder. In turn, this means that the engine can be run on a high load without greater full load enrichment. In this way the same nozzle size and fuel pressure can be maintained despite longer nozzle times at lambda 1.
Better fuel-air mixture cooling during evaporation
This property of ethanol means that the fuel-air mixture is cooled efficiently during the injection which results in improved cylinder filling without needing higher boost pressure.
More aggressive against certain metals and plastic/rubber
Ethanol can be mixed with water and is aggressive towards certain metals including copper and brass. The specification of plastic and rubber must be adapted. Ethanol diffuses more easily through certain types of plastic than petrol does.
The fuel pump has stainless steel housing and carbon commutator. The fuel pressure regulator's diaphragm is in new ethanol resistant material. The bleeder hose to the intake manifold is also in different material. The MIU has been changed so that the tank sensor is pulsed. Continuous measuring would mean the tank sensor having considerably reduced service life due to corrosion.
Engine
The engine can be equipped with an electric engine block heater (option). The intake valves are produced in a new material, and all of the valve seats are also in a new material. The reason for this is that wear is considerably greater when running on ethanol. The spark plugs are harder, BKC7ESC-11. Platinum pins must not be used as the ionisation measurement is disrupted in combination with the ethanol fuel. The exhaust valves have been produced in nimonic material.
Fuel consumption
Consumption increases the greater the proportion of ethanol in the fuel. This is a natural consequence of the need for more ethanol than petrol for a certain air quantity in order to obtain Lambda 1, as well as that ethanol is less energy rich. When driving on pure E85 an increase of up to approximately 40% can be expected.
Service
The service interval is 15 000 km. Oil and filter changes are the principle components of this service. The shorter interval is due to the increased dilution of engine oil resulting from increased quantities of fuel required for starting. In Sweden, E85 contains a red colouring substance that gives a red coating to all engine parts that come into contact with the fuel. The engine oil also becomes redder due to the colouring substance. The interval for spark plug replacement is 30 000 km. The spark plugs face tougher wear when driving on fuel containing ethanol.
Tech 2
When contact has been established with T7, Tech 2 will identify the car as BioPower. A special menu entitled BioPower E85 can then be accessed.
After which, the following procedures are possible:
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Read adapted ethanol content.
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Enter new ethanol content.
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Perform self-adaptation of ethanol content.
Read adapted ethanol content before SPS or control module replacement and re-enter afterwards. Conclude with a self-adaptation. Perform a self-adaptation following repair of the fuel or engine management system. An air leakage or component fault may have caused an incorrect adaptation.
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Higher engine torque and output the greater the proportion of E85 in the tank.
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A greater proportion of E85 involves a greater need for an engine block heater in cold conditions.
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Torque limitation with cold engine and large proportion of E85.
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Shorter service intervals than the petrol variant.
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More frequent spark plug replacement and harder pins (not platinum pins).
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E85 must be handled with the same caution as petrol.
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The red colouring substance in E85 colours the engine oil.
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Spilled oil is treated normally.
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Use Tech 2 in order to correct incorrect adaptations in connection with service action, e.g. SPS, before delivery to the customer.
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Adaptation diagnostic trouble codes and misfiring diagnostic trouble codes could be the result of incorrect adaptation during unfavourable conditions.
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Do not mix up control modules, engine parts or fuel system components that are specially developed for BioPower with components for standard petrol engines or vice-versa.
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