The system does not require any maintenance other than checking the idle speed and periodically replacing the fuel and air filters. The most basic adjustments are described below, all other work should be left to injection system specialists or VW representatives. Adjustment of idle speed and CO content in exhaust gases is described in chapter "Engine adjustment".
Air flow sensor
The air flow sensor plate must be concentric in the housing diffuser. Visually check the position of the plate, if necessary, loosen the central screw and slide the plate to the desired position. Tighten the screw.
The operation of the plate arm and control plunger can be checked as follows:
Turn on the starter for about 10 seconds. Pry up the sensor plate with a screwdriver (pic. F:30) - throughout its entire stroke, the lever must provide the same resistance. There should be no resistance when moving the lever quickly down, otherwise replace the air flow sensor.
If the lever moves up with difficulty, then this indicates a jamming of the regulating plunger. Inspect, clean and repair the plunger and sensor and replace if necessary.
Check the initial position of the air flow sensor plate at normal engine operating temperature after the starter is turned on for 10-15 seconds. The top edge of the plate should be at the same level, or no more than 0.5 mm below the beginning of the narrow part of the diffuser (pic. F:31). If adjustment is needed, lift the transducer plate and squeeze or slightly straighten the wire bracket under the plate (pic. F:32). Do not bend the flat spring at the plate stop.
Check idle speed and CO content in exhaust gases (see chapter "Engine adjustment").
Fuel distributor
Difficulty starting the engine may be due to contamination, corrosion, or sticking of the pressure control valve plunger in the fuel rail. To repair the valve, a repair kit is available that contains all the necessary seals and parts.
Before removing the valve, depressurize the system by disconnecting the high pressure pipe from the engine warm-up control on the side of the engine block, near the dipstick. The high pressure pipe has a large coupling. When loosening the bolt, cover the joint with a rag to prevent fuel splashing.
Unscrew the pressure control valve from the fuel distributor and remove its parts, remembering their relative position (pic. F:33). Keep and reinstall the shims under the valve plug and spring as their thickness is factory set and should not be changed.
Clean the parts and assemble the assembly using new o-rings (shown by arrows in the figure). Tighten the valve plug to the torque specified in section "Technical data". Connect the high pressure hose to the engine warm-up control.
Injectors
The injectors - one for each cylinder - are tightly inserted into the intake ports from the rear (in relation to the car) side of the cylinder head.
The K-Jetronic system is a continuous fuel injection system, meaning all four injectors constantly inject fuel into the intake ports of the cylinder head. To check the injector, pull it out of the hole in the cylinder head, start the engine and let it run on three cylinders. The jet of fuel sprayed from the injector nozzle must have a symmetrical conical shape. Otherwise, the needle or the atomizer spring inside the injector is damaged and the injector must be replaced.
The injectors must not be dismantled, cleaned or repaired.
Before installing the injector, inspect the rubber o-ring and replace it if necessary. Moisten the seal and injector with fuel, insert it into the cylinder head and make sure that it is fully inserted into the hole.
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