Volkswagen Golf/Jetta/Cabriole 1990-1999

General Information

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CIS-E FUEL INJECTION



The CIS-E Motronic system is the latest development of the electronically controlled mechanical Continuous Injection System (CIS). This system uses injectors, fuel pump and air flow sensor that are similar to those on earlier systems. The fuel distributor is equipped with an electronically controlled differential pressure regulator. This is operated by the ECU to control the fuel pressure in the lower chamber of the fuel distributor, which controls air/fuel mixture.

The ECU is now equipped with an adaptive learning program which allows it to learn and remember the normal operating range of the mixture control output signal. This gives the system the capability to compensate for changes in altitude, slight vacuum leaks or other changes due to things such as engine wear. Cold engine driveability and emissions are improved. The new ECU also is capable of cold start enrichment without the use of a thermo-time switch. The Fox still uses the thermo-time switch on CIS equipped vehicles.

The fuel injector pressure has been increased for better fuel atomization and residual pressure. The threads on the new injectors are different so they cannot be interchanged with older units. Some of the other components used on the CIS-E system are similar to those used on the fully electronic engine management systems. Some of the testing procedures are the same but the parts are not necessarily interchangeable.

MOTRONIC AND MOTRONIC 2.9 MULTIPORT FUEL INJECTION (MFI) SYSTEMS



Motronic and Motronic 2.9 systems are developments of the electronically controlled Multiport Fuel Injection (MFI) system. The two systems are almost identical. The engine control module (ECM) monitors engine intake air quantity using the Mass Air Flow (MAF) sensor. This is a true mass air measurement system. Using input from the MAE and other sensors, the ECM can calculate the length of time the injectors should be opened, and also controls the ignition system timing.

The ECM is equipped with an adaptive learning program which allows it to learn and remember the normal operating range of the mixture control output signal. This allows the system to compensate for changes in altitude, slight vacuum leaks or other changes due to other things such as engine wear. Cold engine driveability and emissions are improved.

The ECM is also equipped with a fault memory. If the sensor signal or output solenoid feedback signal is outside preprogrammed parameters, the ECM will store a fault code representing the fault and sensor involved. The ECM will also illuminate the Malfunction Indicator Lamp (MIL) to inform the vehicle operator that the vehicle requires service.



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Fig. CIS-E fuel system components-Volkswagen CIS-E

MONO-MOTRONIC THROTTLE BODY FUEL INJECTION (TBI) SYSTEM



The Mono-Motronic system is development of the electronically controlled Throttle Body Fuel Injection (TBI) system. Based on outputs from the Throttle Position (TP), Engine Coolant Temperature (ECT) and Intake Air Temperature/Fuel Injector Temperature (IAT/FIT) sensors, the Engine Control Module (ECM) can infer intake air flow by air temperature and throttle position. This is a speed-density type control system. The ECM calculates the length of time the injector(s) should be opened, and with input from other sensors, also controls ignition timing.

The ECM is equipped with an adaptive learning program which allows it to learn and remember the normal operating range of the mixture control output signal. This allows the system to compensate for changes in altitude, slight vacuum leaks or other changes due to other things such as engine wear. Cold engine driveability and emissions are improved. The ECM is also equipped with a fault memory. If the sensor signal or output solenoid feedback signal is outside preprogrammed parameters, the ECM will store a fault code representing the fault and sensor involved. The ECM will also illuminate the Malfunction Indicator Lamp (MIL) to inform the vehicle operator that the vehicle requires service.

DIGIFANT MULTIPORT FUEL INJECTION (MFI) SYSTEM



The Digifant Motronic system is development of the electronically controlled Multiport Fuel Injection (MFI) system. This system is quite similar on all models, but there is one significant difference among the three engines, intake air flow is measured using one of two systems. The 1 .8L NA engine is equipped with a Vane Air Flow (VAF) sensor. This is a true mass air measurement system. The 1.8L SC and 2.5L NA engines use a Manifold Absolute Pressure (MAP) sensor.

Along with output from the Intake Air Temperature (IAT) sensor, the ECM can infer intake air flow by air temperature and pressure. This is a speed-density type control system. Using either measurement system, the ECM calculates the length of time the injectors should be opened, and with input from other sensors, also controls ignition timing.

The ECM is equipped with an adaptive learning program which allows it to learn and remember the normal operating range of the mixture control output signal. This allows the system to compensate for changes in altitude, slight vacuum leaks or other changes due to other things such as engine wear. Cold engine driveability and emissions are improved.

The ECM is also equipped with a fault memory. If the sensor signal or output solenoid feedback signal is outside preprogrammed parameters, the ECM will store a fault code representing the fault and sensor involved. The ECM will also illuminate the Malfunction Indicator Lamp (MIL) to inform the vehicle operator that the vehicle requires service. Some vehicles equipped with both the Digifant Motronic system and California specification emissions equipment also have the capability of flashing diagnostic codes.



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Fig. CIS-E fuel control system-Volkswagen CIS-E

Service Precautions


Do not disconnect the battery or the control unit before reading the fault codes. On the Motronic system, fault code memory is erased when power is interrupted.
 
Make sure the ignition switch is OFF before disconnecting any wiring.
 
Before removing or installing a control unit, disconnect the negative battery cable. The unit receives power through the main connector at all times and will be permanently damaged if improperly powered up or down.
 
Keep all parts and harnesses dry during service. Protect the control unit and all solid-state components from rough handling or extremes of temperature.
 

 
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