Cleaning and Checking the Injectors
Cleaning And Checking The Injectors
Background
Complaints about poor starting, idling and acceleration performance have in most cases proved to be due to clogged injectors.
These deposits are caused by unstable petrol components (e.g. olefins) and an insufficiency of suitable solvents combined with corrosion-inhibiting agents.
The deposits give rise to an uneven injection pattern, which in its turn is the cause of uneven fuel distribution in the combustion chambers. This results in uneven and incomplete combustion. The solution to the above problems is to remove the carbon and fuel deposits from the injectors. We therefore recommend the use of "Liquid Fuel Injector Cleaner" solvent in combination with "Saab Injector Cleaner/Tester" equipment for cleaning and checking the injectors.
WARNING
- The mixture of solvent and fuel that is used for cleaning the injectors is highly volatile and inflammable. It is also applied under pressure, which makes it even more advisable to exercise the utmost caution when using it.
- Carry out the work of cleaning the injectors at a safe distance from other work where sparks or a naked flame occur (welding).
- If possible, keep a fire extinguisher near at hand.
- Use approved ventilation/extraction equipment or work outdoors.
- Wear protective gloves and goggles.
Equipment for cleaning injectors:
1a Saab Injector Cleaner/Tester 83 94 264
1b Adapter 83 94 280*)
1c Adapter 83 94 298*)
1d Test box*)
2 Liquid Fuel Injector Cleaner 83 94 272
3 Cable with switch 83 93 886
4 Locking hose-clamp pliers
*) included in 83 94 264
Saab injector Cleaner/Tester:
1 Container
2 Pressure gauge
3 Pushbutton valve
4 Safety valve
5 Pump
Before starting any work
Carry out the work in the following order:
A Cleaning
B Checking
If a check shows that one or more injectors still do not work satisfactorily, repeat the cleaning process and then check them again.
If, in spite of this, an injector still shows too great a difference in performance as compared to the others, it should be changed.
Note: To be sure of a change in flow capacity, it is recommended that checking be carried out before cleaning is started.
Cleaning
1 Disconnect the fuel line from the fuel rail. Fit adapter 83 94 280 with fuel line to the fuel rail.
2 Connect the pressure container's fitting to the adapter and make sure that the valve in the fitting is open.
M1988- cars with a catalytic converter and M1989- cars without a catalytic converter:
Remove the bracket for the dipstick tube and bend aside the tube before fitting the adapter.
-M1987 cars with a catalytic converter and -M1988 cars without a catalytic converter:
Fit adapter 83 94 298 between the fuel line and the fuel rail.
3 Remove fuses 14 and 22.
Start the fuel pump by connecting cable 83 93 886 between the live (battery) side of the holder for fuse 22 and the non-live side of the holder for fuse 14.
Set the switch to the "ON" position.
4 Press the pushbutton on the valve in the container's fitting, causing fuel to flow into the container.
Fill the container with fuel until it is level with the top of the vertical white tube at the bottom of the container. Stop the fuel pump by setting the switch to "OFF".
WARNING: Liquid Fuel Injector Cleaner is a solvent which could be harmful if inhaled and contact with it may also give rise to skin irritation. It is therefore advisable to work only in a well ventilated area and wear protective gloves and goggles.
5 Pour three graduations (ounces) of Liquid Fuel Injector Cleaner solvent, part No.83 94272, into the lid of the container. Pour the solvent into the container.
Mix petrol and solvent by carefully sloshing the mixture around in the container.
6 Make sure that the fuel-solvent mixture does not enter the car's fuel tank, as it could cause damage to the fuel lines and fuel tank. Restrict the fuel return line from the fuel pressure regulator, using a pair of locking pliers or similar. It is important that the jaws of the pliers are rounded so that the fuel line is not damaged.
7 Tighten the lid/pump on the pressure container and pump up the pressure to 1.9 bar (28 psi).
8 Start the car and run the engine at about 3,000 rpm for 20 minutes. Compensate for the pressure drop as it occurs by pumping up the pressure in the container so that it is in the vicinity of 1.9 bar (28 psi).
9 After 20 minutes, switch off the engine and close the valve on the pressure line's fitting with adapter.
10 Release the pressure in the container by pulling the ring of the safety valve.
11 Press the pushbutton valve on the pressure container so that any fuel remaining in the line can run down into the container.
12 Open the return line again by removing the locking pliers.
13 Fit the fuses back in their holders and start the engine. Run it at about 2,000 rpm for 5 minutes, causing all the residual solvent to disappear.
Checking
1 Remove fuses 22 and 14.
2 Open the valve on the pressure line's fitting with adapter. Start the fuel pump by connecting cable 83 93 886 between the live (battery) side of the holder for fuse 22 and the non-live side of the holder for fuse 14.
Set the switch to ON.
3 Press the pushbutton valve on the container for a few seconds, allowing fuel to run out of the system so that any air bubbles will be removed. Stop the pump by setting the switch to OFF.
4 Connect the text box's battery clips to the battery, red clip to positive, black clip to negative. Then unplug all the injector connectors and plug the test box's connector into injector No.1.
Make sure that the lid/pump is fitted on the pressure container.
5 Observe the pressure gauge and increase the pressure by restarting the fuel pump. Set the switch to ON.
Set the switch to OFF and note the reading on the pressure gauge, e.g. 2.2 bar (32 psi). Press the button on the test box to activate injector No.1 for 0.5 seconds. When the injector opens, the pressure will drop and the pressure gauge will show a new fixed reading, e.g. 0.7 bar (10 psi), which should be noted.
Deduct the last reading from the first one, i.e. 2.2 - 0.7 = 1.5 bar (32 - 10 = 22 psi), and note the difference (pressure drop) for injector No.1.
6 Then plug the test box's connector into injectors 2, 3 and 4 one by one and repeat the procedure described in point 1 for each injector. The pressure drop should be the same for all injectors, the maximum permissible difference between them being 0.2 bar (3 psi). If the pressure drop for one or more of the injectors differs by more than this, points 1-13 must be repeated once again.
If variations in pressure drop are excessive after this, the injector or injectors displaying too great a difference should be changed.
7 Release the pressure in the container by pulling the safety valve's ring and then drain the line by pressing the pushbutton valve on the container.
8 Hold a cloth round the adapter fitting and remove the adapter.
Connect the fuel line.
9 Remove the test box connections from injector and battery. Plug all the connectors into the injectors.
10 Fit fuses 22 and 14 back in place.
11 Start the engine and check the fuel system for leaks.