Ignition System: Adjustments

For best results, ignition timing, idle mixture (CO content), and base idle speed must be checked and adjusted simultaneously. Making these checks and adjustments together is very important in order to obtain satisfactory driveablity characteristics and emission levels.
Final adjustment to the idle speed should be made only after the idle mixture is adjusted to specification. Final adjustments to the idle mixture (CO content) should only be made after the ignition timing is adjusted to specification.
Do not attempt to perform this operation without the necessary equipment.
Check and adjust the basic engine settings in the following order:

1. Ignition timing
2. CO content
3. Idle speed
4. Final check of specifications

TEST AND ADJUSTMENT CONDITIONS

1. Engine oil temperature must be at least 176° F (80° C) and radiator cooling fan has operated at least once.
2. All electrical consumers switched "OFF" (radiator cooling fan must not be running during checking or adjusting).
3. A/C switched "OFF".
4. The exhaust system must be free of leaks.
5. There must be no engine vacuum leaks.
6. The oxygen sensor must be connected and operating properly.
7. No fuel pressure measuring equipment connected.
8. If injector lines were loosened or replaced, run the engine up to 3000 rpm several times and then allow to idle for at least 2 minutes before performing any adjustments.
9. Throttle cable adjustment must be OK.

TEST AND ADJUSTMENT SET-UP

1. Put vehicle in PARK or NEUTRAL set parking brake.
2. Turn ignition switch "OFF".

Checking Motronic Ignition:

3. Connect VAG 1367 engine tester using VAG 1367/8 inductive pickup, or suitable timing light and tach.
4. Connect an EPA approved CO tester to the CO tap using VW special tool #6006-0019 high temperature silicone connecting hose, or equivalent.

NOTE: Non-approved connecting hoses may dramatically alter your readings. Adaptor must be connected tightly to CO tap tube to prevent measuring errors.

5. Remove tamper proof plug from air flow sensor assembly.

Crankcase Ventilation Hoses Fox:

6. Disconnect crankcase ventilation hose (A) from the cylinder head cover. Disconnect wiring harness connectors from idle boost valves (B). Remove "T" fitting hose (C) from carbon canister. Place hoses so that only fresh air can be drawn in.
7. Ensure that ignition switch is turned "OFF".
8. Disconnect harness connector from differential pressure regulator.

Diaphragm Pressure Regulator Testing Connections:

9. Connect test adaptor VAG 1315A/1 (or equivalent) between differential pressure regulator and harness connector.
10. Switch suitable multimeter such as the Fluke 83 multimeter to 200 mA range.
11. Connect multimeter to test adaptor VAG 1315A/1 using jumper wires from VW 1594 adaptor kit.
12. Turn ignition switch "ON".
13. Control current must be displayed as positive polarity. If negative polarity is displayed, reverse multimeter test leads.
14. Turn the ignition switch "OFF".

TEST AND ADJUSTMENT PROCEDURE

Ignition Timing Mark:

IGNITION TIMING

1. START the engine and let it idle.
2. Check the ignition timing, checking value is:

4° to 8° BTDC

3. Adjust ignition timing if needed.
4. Loosen the distributor and rotate until specification is correct, adjusting value is:

6° ± 1° BTDC

5. Tighten the distributor bolts to:

18 ft.lb. (25 Nm)

CO CONTENT

1. Check the CO content before adjusting and record the value.
2. To accurately check CO content the idle must be:

800 to 1000 rpm

3. Check the differential pressure regulator control current, checking value is:

4 to 16 mA (must fluctuate)

CIS-E CO Adjustment Screw:

4. If adjustment is needed, adjust the differential pressure regulator control current using a long 3mm hex wrench in the CO adjusting screw, adjusting value is:

10 ± 1 mA (average)

5. If the control current does not fluctuate, check the oxygen sensor. Refer to COMPUTERIZED ENGINE CONTROLS.

CAUTION: During CO adjustment:
Do not push down on the wrench while adjusting.
Do not accelerate the engine while wrench is inserted in CO adjusting screw.
Remove the wrench after each adjustment and briefly raise the engine speed before reading the control current on the multimeter.

6. Observe the CO content, checking value is:

0.3% to 1.2%

IDLE SPEED

1. Check engine idle speed, checking value is:

800 to 1000 rpm

2. If idle speed is OK continue to FINAL CHECK.
3. If adjustment is needed, adjust idle speed using idle air bypass screw, adjusting value is:

900 ± 100 rpm

FINAL CHECK

1. Briefly accelerate the engine to heat oxygen sensor.
2. Allow the engine to idle a few seconds to stabilize readings.
3. Quickly observe and record the basic engine settings.
4. If after completing the entire TEST AND ADJUSTMENT PROCEDURE, all engine settings were within specifications and no adjustments were needed, idle readings should be:

Ignition timing: 4° to 8° BTDC
Differential pressure regulator current: 4 to 16 mA
CO content: 0.3% to 1.2%
Idle speed: 800 to 1000 rpm

5. If adjustments have been made, or the engine is being set to specifications, idle readings should be:

Ignition timing: 6° ± 1° BTDC
Differential pressure regulator current: 10 ± 1 mA
CO content: 0.75% ± 0.45%
Idle speed: 900 ± 100 rpm

6. If engine settings have changed after making adjustments, repeat the entire TEST AND ADJUSTMENT PROCEDURE described above until readings stay within specifications.
7. If specifications cannot be reached, a faulty component may exist and further testing is needed. Refer to COMPUTERIZED ENGINE CONTROLS.
8. Turn the ignition switch "OFF".
9. Remove the test equipment.
10. Reconnect any hoses that were disconnected during the testing, and reinstall the cap on the CO tap tube.
11. Install a new tamper proof plug for the CO adjustment screw in the air flow sensor housing (if removed).