Attention: In the presence of the Digifant system, the supply voltage and resistance for all valve injectors are checked at a common connector. With the Simos system, the test is carried out for each injector separately. The tightness of the injectors and the shape of the fuel jet are checked in the same way in both cases. Removal of valve injectors of the Simos system is carried out in accordance with drawing 24-0389 (see below).
Valve injectors do not inject all the amount of fuel at the same time, which means that in one revolution of the crankshaft half of the fuel required to complete the working cycle is injected.
The nozzle injects fuel in the form of a cone-shaped jet and closes tightly after injection. Leaky injectors make it difficult to start a hot engine. Defects in the injectors cause spontaneous operation of the engine after the ignition is turned off and lead to its stop.
AFT engine: remove the upper part of the intake manifold.
Checking the supply voltage and resistance
Digifant: Disconnect plug -1- for injectors.
Simos: Disconnect the injection valve plug.
Connect a test lamp on semiconductor diodes to the plug. Ask an assistant to turn on the starter. The LED should flash.
Attention: The ABF motor has a 5-pin plug. Contact 5 (against the locking bracket) is connected to ground, pins 1-4 are connected to individual valve injectors. Connect a test lamp in series between pin 5 and pins 1-4
If the LED does not blink, then the reason may be a malfunction of the Hall sensor, a wire break, or the control unit itself. Carry out an electrical check of the injection system, see below.
Switch off the ignition.
Digifant: measure the total resistance of all valve injectors at connector -2-. The prescribed resistance value is 3.7-5.0 ohms.
Note: If the measured value does not correspond to the prescribed value, it can be concluded, depending on the measured value, how many valve injectors are defective. With a defect in one injector, the measured value should be 5.0-6.7 Ohm: with a defect in two injectors - 7.5-10.0 Ohm; with a defect in three nozzles - 15.0-20.0 Ohm.
ABF motor: measure the resistance in series between pin 5 and pins 1-4. The prescribed resistance value is 15.0-20.0 ohms.
If the resistance at connector -2- is greater than 5 ohms, remove the wire guide from the fuel distributor bracket and, as with AFT/ADY/AGG engines, perform an individual injector test.
AFT/ADY/AGG engines: connect a test lamp between the contacts of a separate valve injector. The prescribed resistance value is respectively 15.0-20.0 ohms.
Replace valve nozzle if necessary.
Checking the jet shape and tightness (Digifant/Simos)
Disconnect the high voltage wire from the ignition coil at the ignition distributor and connect it to ground, if necessary, use an auxiliary wire.
Remove the intake air hose together with the idle speed stabilization valve, and the bracket and crankcase breather pressure control valve. First release and slide back the fastening clamps.
Disconnect plug -1- from wire guide.
Disconnect the wire guide -2- from the holders of the fuel distributor (arrows).
Remove bolts -3- and -4- for fuel distributor.
Unscrew the throttle valve pipe from the intake manifold, to do this, loosen 4 bolts with turnkey sockets at the flange.
Remove valve injectors complete with fuel distributor and wire guide from the exhaust manifold. Valve nozzles are only inserted and can be easily removed.
Insert valve nozzles into a suitable measuring vessel.
Disconnect the blue plug from the temperature sensor at the coolant connection.
Between the contacts of the plug from the temperature sensor, connect a resistance of 15 ohms.
Connect the plug -1- of the injector to the wire guide block -2-.
Ask an assistant to turn on the starter for a few seconds and at the same time compare the shape of the fuel jets of valve injectors. The jets of fuel from all nozzles must have the same conical shape.
Switch off the ignition.
Disconnect plugs from valve injectors.
Turn on the ignition for about 5 seconds, do not turn on the starter. No more than two drops of fuel should come out of the injector nozzles within one minute.
Install valve injectors.
Attention: When installing the injectors, make sure that the O-rings are not damaged.
Check rings for damage, replace rings if necessary. Moisten the O-rings with fuel before installing.
Install the fuel distributor, wire guide and intake hoses in reverse order. Secure the hoses with clamps tightened with screws.
Screw the throttle valve to the intake manifold, remembering to install the gasket. Tighten the 4 hexagon socket head screws crosswise to 20 Nm.
Connect the high voltage wire to the ignition coil.
AFT engine: Install upper intake manifold.
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