Checking the pressure regulator
For accurate measurement of fuel pressure, a special pressure gauge VAG 1318 is used with additional parts, which allows you to measure control values. The idle pressure is 3.5 bar. If the vacuum hose is removed at the point indicated by the arrow, the pressure will rise to 4.0 bar. After the engine has stopped, the pressure must be at least 3.0 bar. However, the pressure may drop to 2.5 bar after 10 minutes.
Checking the injectors
To check the injectors, check the voltage supply and the injectors themselves. Requires an LED voltage probe.
Checking the voltage supply: for small motors, remove the motor cover (big part in the middle of the engine). To do this, turn the two quick couplings a quarter of a turn to the left with a screwdriver, unhook the cover and remove it. For other engines, remove the two fastening clips on the right side of the trim, unhook the trim on the left side and remove the trim. Pull the cover above the injectors upwards at the rear edge and then disengage it from the front.
Pull the plugs off the injectors. They are attached with wire fasteners.
Connect the LED voltage probe to the pins of the removed plug. If you now turn the engine with a starter (assistant), then the LED should flash. If this is not the case, then it can be assumed that the voltage supply is broken (probe may be defective).
Checking the injectors: first remove all plugs from the injectors. Connect an ohmmeter to both pins of the #1 injector plug. Resistance values should be 14-16 ohms (low power motors), or 11-13 Ohm (other engines).
If the resistance values are as above, the injectors can be removed. They must be removed together with the fuel distributor tube. Leave the plug connected at the injector and do not disconnect the fuel lines.
Place the injectors in 4 different measuring jars and have an assistant turn on the starter. The cone-shaped fuel jet leaving the injectors must be the same for all injectors.
Switch off the ignition, remove all plugs from the injectors and switch on the ignition again. Turn the ignition off again and then turn it on for another 5 seconds. No more than 2 drops of fuel should come out of each injector. If so, then the injectors are tight.
Removing the injectors
Remove cover (cover) engine as described earlier.
Pull off the vacuum hose (3) with fuel pressure regulator (1).
Temporarily remove the fuel tank cap (for pressure relief).
Fuel line connection (2) cover with a thick cloth and very slowly unscrew the connection with an open end wrench (holding the other side of the connection). If fuel spills out, it will soak into the rag.
Disconnect plugs from injectors (4, 5, 6 and 7). In doing so, push down the wire fasteners on the rear side.
For 1.8l engines, disconnect the plug from the Hall sender.
Unscrew the fuel distributor pipe from the fuel line (2 bolts) and lift the distributor tube together with the injectors up. The figure shows injectors with the connections already mentioned.
1 Fuel return line
7 Fuel supply line
3 Fuel distributor pipe
4 Fuel pressure regulator
5, 6, 7, 8 Injectors
To install the injector, remove the mounting bracket from the distributor tube and remove the injector from the tube.
Installation is carried out in the reverse order of removal, observing the following conditions:
Always replace O-rings. Under no circumstances should the plastic cap be removed from the injector in order to replace the front O-ring, it is pulled through the plastic cap. Lubricate the ring with clean engine oil.
Check that the mounting brackets are seated correctly.
Press the injectors vertically into the correct position on the distributor tube until they are fully seated and then secure them with the fastening brackets.
Install the fuel distributor pipe with the installed injectors into the fuel line and press evenly until it sits correctly.
Screw in the bolts, slowly press the fuel distributor pipe against the fuel line by hand and tighten the bolts to 1 Nm.
Checking the coolant temperature sensor
The sensor performs a dual task. First, it reports the engine coolant temperature and second, it connects to a remote thermometer on the instrument panel. Sensor (2) located on the back of the cylinder head. If an air conditioner is installed (engine 1.8 l). then the second temperature sensor (1) is located directly nearby.
To check, do the following:
- Disconnect the plug from the sensor in the coolant pipe at the rear of the cylinder head.
- Connect an ohmmeter to the two pins of the plug 1 and 3.
- With a cold engine and room temperature, the ohmmeter reading should be between 1.5 and 3.0 kΩ. If not, install a new sensor.
Checking the intake air temperature sensor
The sensor is installed only on turbocharged engines. Sensor (2) installed next to the throttle control unit (1).
Remove the plug from the sensor.
Connect an ohmmeter to both terminals of the sensor. With a cold engine and room temperature, the resistance should be 1.6-2.8 kOhm. Otherwise, replace the sensor.
Checking the air mass meter
Only the voltage supply to the air mass meter and the connection to the control box can be checked if there is not sufficient experience in electrical measurements. If the flow meter does not pass the described checks, then further checks must be carried out in a workshop. Flowmeters for "atmospheric" engine and turbo engine are different. On a naturally aspirated engine, the flow meter is mounted on the air filter; on a turbocharged engine, it is integrated into the air filter housing. An LED tester is required to test.
Disconnect plug from air mass meter.
Connect the probes of the LED probe between the contact "3" plug and "weight".
Air mass meter plug with 3 pins (non-turbo engine)
Air mass meter plug with 4 pins (turbocharged engine)
The assistant should turn on the starter (the engine will start). If the LED lights up, then voltage is applied to the flowmeter.
To check the connections of the control unit, turn off the ignition and remove the plug from the unit. Now you need to check the passage of current.
On the plug for the non-turbo engine, connect an ohmmeter between the pin (1) on the plug of the control unit and contact (2) air flow meter plug. In addition, measure the resistance (9) and contact (2). In both cases, there must be conductivity (Ohm).
Measurement of idle speed and CO content
Idle speed is adjusted automatically. With a warm engine and disconnected consumers, the revolutions are 820-90 rpm. The CO content in the exhaust gases cannot be measured by simple means, so you should contact a workshop for this.
Visitor comments