| General notes on injection |
| Ignition system: repairing |
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| The control unit for the fuel injection and ignition system is equipped with self-diagnosis. Before carrying out repairs and fault finding the fault memory of all control units must be interrogated using the automatic test sequence. This is necessary because there are several control units interconnected via the data bus. Also check vacuum hoses and connecting pipes (unmetered air). |
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| To fix the fuel hoses in the engine bay only use spring-type clamps. Screw-type clamps must not be used. |
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| Disconnecting and connecting the battery must only be done with the ignition switched off, otherwise the engine control unit could be damaged. |
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| For trouble-free operation of the electrical components a voltage of at least 11.5 V is necessary. |
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| Do not use sealants containing silicone. Particles of silicone drawn into the engine, will not be burnt in the engine and damage the Lambda probe. |
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| If the engine starts, runs for a short period and then stops, after fault finding, repairs or component tests, then the fault may lie with the immobilizer which is blocking the engine control unit. The fault memory must be interrogated and if necessary the control unit matched → Chapter. |
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| During some checks it is possible that the control unit will recognise and store a fault. Therefore after completing all checks and repairs, the fault memory must be interrogated and if necessary erased → Vehicle diagnosis, testing and information system VAS 5051, Fault memory: consulting and clearing. |
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| Vehicles with airbags are fitted with a crash fuel shut-off system. It reduces the risk of a vehicle burning in the event of a crash in that the fuel pump is switched off by the fuel pump relay. At the same time this device improves the starting of the engine. When the door is opened the fuel pump is activated for 2 seconds to build-up pressure in the fuel system. |
| Checking intake system for leaks (unmetered air) → Chapter. |
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