Pressure regulator
An appropriate pressure gauge is required to measure pressure (V.A.G 1318) with stopcock and adapter.
Nominal value at idle approx. 3.5 bar; in the vacuum hose removed from the pressure regulator, about 4 bar.
The minimum maintained pressure immediately after turning off the engine is at least 3 bar; after 10 minutes about 2.5 bar.
Checking injection valves
The connector is disconnected here (1) injection valve (2). The voltage indicator with LED checks the voltage supply to the injection valves.
1. Checking the voltage supply: remove the lining of the engine compartment with a displacement of 1.6 liters (chapter Body parts); for a 1.8 liter engine, first pull the cover above the injection valves upwards at the rear edge, then remove it from the front.
2. Disconnect the injection valve connectors. To do this, press the wire clamps on their reverse side.
3. Connect a voltage indicator with LED to the contacts of the disconnected connector.
4. Have a helper turn the engine over with the starter.
5. The voltage indicator LED should flash, otherwise the defect is in the wire connected to the injection valves, or in the Motronic control unit itself.
6. Injection valve check: Disconnect all injection valve connectors.
7. Connect an ohmmeter to both pins of the first injection valve.
8. Rated value: 14-16W (engine 1.6 l) and 11–13 W (engine 1.8 l).
9. Deeper check (jet type and tightness):
10. Remove the injection valves together with the distributor tube - see chapter above. But the wire connectors remain connected and the fuel lines are screwed on.
11. Close the holes in the injection valves with suitable plugs.
12. Dip injection valves into four measuring cups.
13. Let your assistant crank the engine with the starter for a few seconds: the injection jet should be the same for all valves. Then the picture of the type of jet is in order.
14. Disconnect all injection valve connectors.
15. Turn off the ignition and then turn it on for about 5 seconds: no more than 2 drops should come out of each valve. In this case, the valves are sealed.
For turbo engine, intake air temperature sensor (2) located on the intake manifold behind the throttle control assembly (1).
This 1.8 liter air-conditioned engine has two temperature sensors on a flange behind the cylinder head. Numeric «1» the air conditioner sensor is indicated. Numeric «2» – Ignition/injection system sensor and temperature indicator.
For an engine with a displacement of 1.6 liters, the temperature sensor is in the same place.
The figure shows the placement of the sensor pins.
The figure shows a fresh air flow meter flanged to the air filter of naturally aspirated engines with a displacement of 1.6 and 1.8 liters.
- 1 - hot-wire conductive plate support;
- 2 - passage for air.
The pinout information of the 3-pole connector is used to test the fresh air flow meter in naturally aspirated 1.6L and 1.8L engines.
On the 1.8l turbo engine, the fresh air flow meter is integrated into the air filter housing. connector (2) available from above.
The pin assignment information of the 4-pole connector is used when testing the 1.8L turbo engine fresh air flow meter.
Checking the coolant temperature sensor
The coolant temperature sensor is a dual function device that provides information to the ignition/injection system with one pair of contacts and the combined instrument panel with the other pair of contacts. Here we check the assembly associated with the ignition / injection system.
1. Disconnect the sensor connector in the coolant supply pipe behind the cylinder head.
2. Connect an ohmmeter to the contacts «1» And «3» sensor connector.
3. Read the resistance value when the engine is cold and at room temperature (around 20°C).
4. Rated value: 1.5-3.0 kΩ.
5. If the nominal value is obtained, the sensor is OK.
Checking the intake air temperature sensor
1. Disconnect the connector on the sensor.
2. Connect an ohmmeter to the sensor connector pins.
3. Read the resistance value when the engine is cold and at room temperature.
4. Rated value: 1.6-2.8 kΩ.
5. If the nominal value is obtained, the sensor is OK.
Fresh air flow meter
On your own, you can check the voltage supply to the fresh air flow meter and the passage of the signal through the wires to the control unit. If both are in order, then with a defect in this node (poll the computer) The fresh air flow meter is considered faulty:
1. Disconnect the connector on the fresh air flow meter.
2. Look at the numbering of the contact tabs in the figure.
3. Voltage test: For 74KW and 92KW motor, connect a diode test lamp between the terminal «3» on the three-pole connector of the connected wire and «weight» (engine block).
4. For a 110 kW turbo engine, connect a diode test lamp between the terminal «3» on the four-pole connector of the connected wire and ground (engine block).
5. Have your helper turn the engine over with the starter (the engine might even start): the LED should flash, in which case the voltage is applied.
6. Checking the signal path: turn off the ignition. Disconnect the connector «A» on the control unit.
7. Using an ohmmeter, check the conductivity of the wires:
8. With 74KW and 92KW motors from pin «1» on the connector of the control unit «A» to contact «2» on the three-pole connector of the fresh air flow meter. In addition, from the pin «9» on the connector of the control unit «A» to contact «3» on the three-pole connector of the fresh air flow meter.
9. With 110KW turbo motor from pin «1» on the connector of the control unit «A» to contact «4» on the four-pole connector of the fresh air flow meter. In addition, from the pin «9» on the connector of the control unit «A» to contact «2» on the four-pole connector of the fresh air flow meter.
Removing injection valves
1. Remove the lining of the engine compartment of the engine with a displacement of 1.6 liters (chapter Body parts); with the 1.8 l engine, first pull the trim up at the rear edge, then remove it from the front.
2. Disconnect the vacuum hose from the fuel pressure regulator.
3. Briefly open the fuel tank cap to relieve pressure.
4. Loosen the screw connection of the fuel supply line. Be careful! Residual pressure! When opening the pipeline, cover it with a rag. Let the escaping fuel drip onto the rag.
5. Dismantle the recirculating petrol pipeline.
6. Disconnect the injection valve connectors. To do this, wring out the wire clamps on their reverse side.
7. For engines with a displacement of 1.8 liters, disconnect the Hall sensor connector.
8. Unscrew both fixing bolts of a distributive tube of fuel.
9. Remove the fuel distributor pipe together with the injection valves.
10. If you need to dismantle one injection valve, then remove the mounting clamp and remove the valve from the distribution tube.
11. During installation, make sure that the O-rings and rubber O-rings are replaced.
12. When replacing the rubber O-ring, under no circumstances wring out the plastic cap on the valve.
13. Lubricate all rubber parts with oil before installation. Insert the valves together with the distribution tube.
Plug connectors at the rear left in the engine compartment in an engine with a working volume of 1.6 liters
- 1 - lambda probe connector (black);
- 2 - knock sensor connector (green);
- 3 - plug connector engine speed sensor (grey).
Connectors at the rear left in the engine compartment in an engine with a working volume of 1.8 liters
- 1 - lambda probe connector (black);
- 2 - plug connector engine speed sensor (grey);
- 3 - knock sensor connector I (green);
- 4 - knock sensor connector II (blue).
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