C3. Ignition System Interference

To check

Ignition system interference can occur on 4-cylinder cars equipped with the Motronic engine management system. The "ticking" sound is heard at its loudest when the engine is idling and diminishes with increasing engine rpm.

Procedure

The fault can be rectified by fitting interference suppression kit 49 00 015 (CA=30567189) (4 grounding braids) as described below:

Braid 1, between engine block and cross-member

1. Remove the air intake resonating chamber.





2. Fit the grounding braid between left-hand side of the engine block and the strut tower brace, as shown.

3. Secure the braid to the throttle cable by means of a cable tie. The braid should be slack between the engine and the cable tie to allow for engine movement.

4. Refit the resonating chamber.

Braid 2, between A/C pipe and left-hand part of subframe

1. Raise the car.





2. Drill a hole with a 3.5 mm (5/32 in.) bit in the left-hand part of the subframe about 100 mm (4 in.) from the bend at the front, see illustration.

3. Secure one end of the braid by means of a sheet metal screw.

4. Seal with anti-corrosion agent.





5. Run the braid along the subframe and fasten it under the A/C pipe's plastic clamp.

6. Fit the hose clamp in place at the A/C pipe's joint on the compressor side.

7. Run the braid between the A/C pipes and position it round the bright-polished metal nut (compressor side).

8. Pull it tight and fasten it securely with the hose clamp.

9. Secure the loose end of the braid to the gearbox's grounding point. Make sure that the braid has sufficient slack to take up movements of the engine.

Braid 3, between engine block and right-hand part of subframe





1. Drill a hole with a 3.5 mm (5/32 in.) bit in the right-hand part of the subframe about 100 mm (4 in.) from the bend at the front, see illustration.

2. Secure one end of the braid by means of a sheet metal screw.

3. Seal with anti-corrosion agent.

4. Pull up the braid and fasten the other end with the screw securing the clamp for the oxygen sensor's lead.

5. Secure the braid with a cable tie round the compressor bracket's mounting lug. Make sure it has sufficient slack to take up the movements of the engine.

Braid 4, between catalytic converter and subframe





1. Drill a 3.5 mm (5/32 in.) hole in the rear part of the subframe, see illustration.

2. Fasten the braid in place.

Seal with anti-corrosion agent.

3. Fasten the other end to the exhaust pipe clamp next to the catalytic converter by means of the nut supplied.

4. Lower the car to the floor.