Note: Wiring diagrams can be found later in the book, in chapter of the same name.
Checking injection nozzles
Disable the ignition system according to the scheme described in chapter «Ignition system».
To check whether gasoline is entering the injection system, loosen the bolts on the fuel supply line.
Don't forget a rag, because in most cases gasoline will splatter from the fuel line. Otherwise, ask the assistant to work as a starter.
If fuel is coming in, then the supply is in order. Therefore, in the second place it is necessary to check the nozzles themselves.
Remove nozzle, description see later in this chapter. To do this, the upper part of the intake manifold must first be removed.
Keep a container or rag ready to collect fuel.
Remove the large air duct between the ECM and throttle body to gain access to the check valve.
Remove fuse 17 in the fuse box (chapter «Body electrical system»).
Using a piece of wire (auxiliary cable), connect «plus» battery pack with rear contact fuse box (in the direction of travel). The fuel pump should work.
Slightly raise the valve on the distributor by hand. Now the nozzle should inject gasoline cone-shaped. Otherwise:
Raise the stop valve once until it stops. Repeat check.
In the same way, it is possible to check the difference in the amount of injected fuel between the individual cylinders. However, this method is suitable only for lack of a better one.
Direct all four or five injectors respectively to four or five measuring containers, without bending the fuel line hoses.
Raise a little (about 2 cm) stop valve.
The assistant must support the said jumper until 20 cm3 is collected in the first container (ml) fuel.
Left: starting fuel valve (2) with connection plug (1) in a 5-cylinder engine.
Right: starting fuel valve (arrow) in a 4-cylinder engine.
In the illustration on the left you see an air mixture corrector with a shut-off valve (4), air nozzle (3), air filter (2) with inlet hose removed (1).
The illustration on the left shows the correct position of the check valve with air nozzle. It should be exactly a = 1.9 mm below the upper edge of the narrow cylindrical part of the air nozzle. Adjust if necessary by slightly bending the spring (presented in the figure in the form «snakes»). Note: Newer air mass meters have an adjusting bolt instead of a spring. In this case, the position of the shut-off valve is adjusted by said bolt.
Compare the amount of injected fuel. The difference should not be more than 2.5 cm3.
In case of large deviations, swap the injectors with the highest and lowest values. Repeat measurement.
If deviations «moved» along with the injectors, then it is time to replace the injectors with the corresponding deviations.
If you received the previous measurement results for cylinders with deviations, then it is possible that the fuel line to the injector is narrowed or the dispenser is faulty.
Injector leak test: if the fuel pump is turned off after two minutes of operation with the shut-off valve raised (remove jumper), no fuel should come out of the injectors.
Checking the starting fuel valve
Disable the ignition system according to the scheme described in chapter «Ignition system».
Remove the starting fuel valve, remove the wire end, leave the fuel line tube connected.
Operate the starter a little so that the fuel pump can build up pressure.
Lower the nozzle into the container, connect two auxiliary wires to the valve contacts.
Connect the free ends of the wires to the battery terminals - one with «+», another with «-».
The valve should now spray gasoline conically.
Leak test: Remove auxiliary wires.
Operate the starter a little more to pressurize the fuel pump
Wipe valve clean. Within a minute, the flow of gasoline should not be observed.
Checking the fuel dispenser
Run the engine or starter for a short time to build up full fuel pressure.
Remove cover and air filter element.
Remove the large air duct between the air mixture adjuster and the throttle body.
The shut-off valve is now visible, which must be fully pulled up. This process should be carried out all the time with the same effort.
There should be no resistance when pressing the stop valve quickly. Otherwise, the air mass meter must be replaced.
If the shut-off valve can only be pulled out with great difficulty, but it drops very easily, then the control piston is stuck in the fuel dispenser. Replace fuel dispenser.
Idling stabilization control valve (arrow) 4-cylinder engine is located behind the cylinder head cover (pic. left). The idle control valve for the 5-cylinder engine is located on the right front near the cylinder head (pic. on right).
Checking the air mass meter
Warm up engine to operating temperature or run hot engine for about 10 seconds before checking.
After loosening the clamps, remove the air intake sleeve between the corrector of the composition of the combustible mixture and the throttle body
Check the shut-off valve: it must be on the side facing the injection pipe, 1.9 mm below the upper edge of the narrow cylindrical part of the air nozzle, at most 3 mm deeper (see picture top left).
If the valve is not positioned correctly, it can be pulled up and corrected by bending the mounting wire bracket at the bottom of the air flow meter channel. Never bend the spring!
Check now if the check valve is touching the walls.
If so, loosen the central fixing screw and re-center the valve.
After this adjustment, it is necessary to recheck the idling and the CO content.
Idle speed stabilization test
Switch on the ignition, touch the control valve with your hand: a working vibration should be felt, otherwise either the control valve or the control unit of the KE-III-Jetronic injection system is faulty.
Check control valve: Remove plugs. Measure the resistance between the plug contacts of the control valve: it should be negligible. Meaning «infinity» means a winding break - a defect in the distribution valve.
If the control valve is in order, then the source of the malfunction can be assumed to be a broken wiring or a faulty control unit. Check and replace if necessary.
Connect an LED voltmeter to both poles of the free end of the wire.
Turn on the ignition.
The voltmeter should light up, in which case the power supply from the KE-III-Jetronic injection system control unit is OK.
Checking the throttle angle sensor (models with manual transmission)
Ohmmeter contacts cannot be connected directly to sensors, one of which is located below the throttle body. Therefore, only the plug connection accessible from above is separated. Measure the resistance in the sensor wire.
Idle signal switch: connect an ohmmeter to pins 1 and 2 of the plug.
Throttle in idle position: 0 ohm reading. Slightly open the throttle: the indicator should go to 8 ohms.
Full load signal switch: Connect an ohmmeter to pins 2 and 3.
Throttle in full load position: 0 ohm reading. Slightly close the throttle: the indicator should go to ∞ Ohm.
Models with 5-cylinder engine and automatic transmission (throttle potentiometer test)
Disconnect the three-pole plug of the throttle valve potentiometer,
To check, connect an ohmmeter to pins 1 and 2:
The indicator should be 1.5-2.6 kOhm.
Now connect an ohmmeter to pins 2 and 3:
The indicator should be 0.75-1.3 kOhm.
Open throttle slowly, ohmmeter connected.
The resistance should rise to a maximum of 3.6 kΩ.
Note: The throttle valve potentiometer can be adjusted. However, after this it is necessary to «basic adjustment» automatic transmission is a workshop business.
Left: 4-cylinder throttle body with air intake sleeve removed.
1 - gas thrust eccentric;
2 - throttle valve;
3 - throttle angle sensor.
Right: The plug connection for the throttle angle sensor is located in the 4-cylinder engine on the left side of the intake duct (arrow).
With the air intake hose removed in a 5-cylinder engine, both throttle valves can be seen in the throttle body (3 and 4). On top of the node is a system of drive rods (2), which first opens one, and when you further press the accelerator pedal, the second throttle. Position (1) displays the idle signal switch.
Right: for removing injection nozzles (4 cylinder engine) unscrew the fixing screws (3 and 4), remove the injector fasteners (holders) (1 and 2), take out the injection nozzles.
Checking engine temperature sensors
The vehicle with a 5-cylinder engine and KE-III-Jetronic injection system is equipped with a dual temperature sensor for the injection system and a fully electronic ignition system. Measurements for these sensors are made from each of both contacts to «mass» (cylinder block). In a 4-cylinder engine, measurements are taken between both contacts.
4-cylinder engine: Connect an ohmmeter to both plug contacts of the temperature sensor.
5-cylinder engine: connect an ohmmeter to one of the two terminals and to «mass».
For everyone: the resulting resistance value depends on the temperature.
You can check from the diagram on the next page if the measured values of the sensors are in the correct range.
Lambda control test (4 cylinder engine)
Checking the power supply of the lambda probe: disconnect the plug connection of the lambda probe.
Connect a voltmeter at the cable of the control unit to both plug contacts.
Start the engine: if voltage is present, then the power supply of the lambda probe is in order. Otherwise, check the wiring.
Checking the heating of the lambda probe: connect an ohmmeter lead of the lambda probe to both plug contacts.
With proper heating, the readings should be 3-15 ohms. In case of other indications, the lambda probe should be replaced.
Checking the lambda probe signal: disconnect the wire, connect a voltmeter between the wiring to the control unit and ground (corps).
Turn on the ignition. The indicator should be 400-700 mV.
Otherwise, check the wiring.
To test the probe, connect an ohmmeter between «weight» motor and probe signal wire.
Normalized reading ∞ Ohm. Otherwise, the probe is defective.
Lambda control test (5-cylinder engine)
Although checking the functioning of the lambda control can be done relatively easily, however, it requires a matching wire and an ammeter, which is available to many electronics enthusiasts. Or you can check with a gas analyzer to determine the CO content. The following is a description of the test:
Warm up the engine.
Remove the pressure regulator plug, connect the measuring adapter you made from two suitable plugs and a piece of wire, connecting the wiring and the pressure regulator.
Separate one of the matching wires and bring it to the measuring device (mA range).
Start the engine and leave it to idle.
Write down the result.
Pull out the dipstick.
The diagram shows the resistance value of the coolant temperature sensor as a function of temperature. (See the following figure)
The current in the control circuit must increase.
Otherwise, one of the components of the lambda control is faulty.
In this case, try to separate the plug connection to the lambda probe and hold the green wire to the control unit for about 20 s for «mass».
If now the current in the control circuit changes, then the KE-lll-Jetronic injection system control unit is in order, but the lambda probe is faulty - replace.
If nothing happens, then the injection system control unit is faulty.
Note: The basic prerequisite for a functioning lambda control is a correct basic idle setting, which means that the CO content is correct, otherwise the control will always be at one end of the standard range. The same conditions are created if the mixture is greatly depleted of unaccounted for air.
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