Ignition Timing, Idle Speed, CO Content (Digifant II)

DIGIFANT II





Ignition Timing, CO Content, and Idle Speed Checking/Adjusting

Note: Check and adjust the basic engine setting in the following order:
- Ignition timing
- CO content
- Idle speed

Test and adjustment conditions:

- Engine oil temperature must be at least 80°C (176°F) and radiator cooling fan has operated at least once.
- All electrical consumers switched OFF (radiator cooling fan must not be running during checking or adjusting).
- Idle switch functioning properly.
- Idle stabilization system OK (the valve must vibrate and hum while engine is running).
- Switch ignition OFF.
- Connect VW 1367 engine tester.
- Connect SUN 105 CO Tester (or EPA approved equivalent) to CO tap tube using Special Tool 6006-0019 or equivalent (high temperature silicone connecting hose).

Note: Non-approved hoses may dramatically alter your readings.




Ignition timing

- Start the engine and raise speed to a minimum of 2100 RPM tour times, letting the throttle close each time.

Note: This clears the fault memory in the E.C.U. and cancels the hot-start idle increase function. This must be repeated each time the vehicle is stopped and re-started during the test procedure.

- Remove connector from coolant temperature sensor (Arrow).
- Increase engine speed to 2300 ± 50 RPM and check ignition timing.
- Specification:
Checking: 4° to 8° BTDC
Adjusting: 6° ± 1° BTDC

If adjustment is necessary:

- Loosen distributor and rotate until specification is correct.
- Tighten distributor clamp bolt to 25 Nm (18 ft-lbs.).

CO content

Note: Be sure to check the Emissions Label under the hood.

- Disconnect coolant temperature sensor.
- Raise dipstick slightly to allow for crankcase ventilation, then clamp crankcase breather hose near PCV valve shut.
- Adjust idle speed to 800 ± 50 RPM.

Idle CO Specification Chart:

- Check CO specification.

Idle CO Tolerance Chart:

- CO reading must fall within band on Checking Tolerance graph.

If CO reading does not fall within tolerance band:

- Remove tamper-proof plug from adjustment location on airflow sensor by drilling into plug with a 2.5 mm (0.098 in.) drill bit.
- Thread a 3 mm (0.137 in.) sheet metal screw into the drilled hole.
- Pull out screw (with plug) using pliers.



- Adjust CO as necessary by using a 5 mm hex wrench to turn adjusting screw in air flow sensor (2).
-Specification: adjust CO content according to Adjusting Specification graph.




Idle speed

- Remove clamp from crankcase breather hose and re-seat oil level dipstick.
- Set base idle speed.
- SpSpecification975 ± 50 RPM
- Reconnect coolant temperature sensor.
- Idle speed must drop to 800 ± 50 RPM
- CO% must go up to 0.7% ± 0.4% (at any altitude).

If OK,

- Install a new tamper-proof plug over CO adjustment screw (if removed).
- Disconnect test equipment.

If only the idle speed is not OK:

- Check idle switch and wiring.
- Check idle stabilization system.

If only the CO% is not OK:

- Check the oxygen sensor system.

If the idle speed and CO% are not OK:

- Check the coolant temperature sensor and wiring.