Federal
Making these checks and adjustments together is very important to both driveablity and emissions control. If the equipment necessary to accurately perform this work is not available, we suggest turning the job over to a local repair shop that has the needed test equipment. In a properly equipped shop, these checks and adjustments can be made quickly, accurately, and at resonable cost.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. Idle switch is functioning properly.
5. Idle stabilization system operating properly, the valve must vibrate and hum while the ignition is "ON".
6. The exhaust system must be free of leaks.
7. There must be no engine vacuum leaks.
8. The oxygen sensor must be operating properly.
TEST AND ADJUSTMENT SET-UP
1. Turn ignition switch "OFF".
2. Connect VW 1367 engine tester (or suitable timing light and tach.)
3. Connect an EPA approved CO tester to the CO tap tube using VW special tool #6006-0019 high temperature silicone connecting hose, (or equivalent).
NOTE: Non-approved connecting hoses may dramatically alter your readings.
IGNITION TIMING
1. START the engine and raise the engine speed to a minimum of 2100 rpm four (4) times, letting the throttle close each time, (make sure engine has reached operating temperature).
NOTE: This clears the fault memory in the Digifant II control unit and cancels the hot-start idle increase function. This procedure must be repeated each time the vehicle is stopped and re-started during the test procedure.
Coolant Temperature Sensor Connector:
2. Disconnect the harness connector from the blue engine coolant temperature sensor.
Ignition Timing Mark:
3. Increase the engine speed to 2300 ± 50 rpm and check the ignition timing. Specifications are:
Checking: 4° to 8° BTDC
Adjusting: 6° ± 1° BTDC
4. If adjustment is necessary, loosen the distributor clamp bolt and rotate the distributor until specification is correct.
5. Tighten the distributor clamp bolt to:
18 ft.lb. (25 Nm)
5. Reconnect the blue coolant temperature sensor.
CO CONTENT
Coolant Temperature Sensor Connector:
1. Disconnect the blue coolant temperature sensor.
2. Raise the dipstick slightly to allow for crankcase ventilation.
Crankcase Ventilation Hose:
3. Disconnect the crankcase ventilation hose from the emission control valve and plug the hose.
Idle CO And Idle Speed Adjustments:
4. Adjust the idle speed using the idle air bypass screw to:
800 ± 50 RPM
NOTE: This idle speed setting is used only for CO adjustment. The idle speed must be adjusted to a different specification after adjusting the CO volume.
5. Check the CO specification.
6. Record the CO value before adjusting.
Digifant II Idle CO Graph:
7. CO reading must fall within band on Checking Tolerance graph.
8. If CO reading does not fall within the tolerance band, proceed with adjustment.
9. Remove the tamper-proof plug from the CO adjustment screw location on air flow sensor by drilling into plug with a:
0.098 in. (2.5 mm) drill bit
10. Thread a sheet metal screw into the drilled hole using a:
0.137 in. (3 mm) sheet metal screw
11. Pull out the screw (with plug attached) using pliers.
12. Adjust the CO as necessary by adjusting the CO adjustment screw in the air flow sensor with a:
5 mm hex wrench
13. Adjust the CO content according to the Adjusting Specification graph.
IDLE SPEED
1. Remove the plug from the crankcase ventilation hose and connect the hose to the emission control valve.
2. Re-seat the oil level dipstick.
Idle Air Bypass Screw:
3. Adjust the idle speed using the idle air bypass screw. Adjust idle speed to:
975 ± 50 RPM
FINAL CHECK
1. Reconnect the harness connector to the blue coolant temperature sensor.
a. Idle speed must drop to:
800 ± 50 RPM
b. Idle CO must be:
0.7% ± 0.4% at any altitude
2. Install a new tamper-proof plug over the CO adjustment screw, if it was removed.
3. Disconnect the test equipment, and reinstall CO tap cap.
4. If only the idle speed is NOT OK:
a. Check the idle switch and wiring. [1]
b. Check the idle stabilization system. [1]
5. If only the idle CO% is NOT OK:
a. Check the oxygen sensor system. [1]
6. If the idle speed and idle CO% are NOT OK:
a. Check the coolant temperature sensor and wiring. [1]
[1] Refer to COMPUTERIZED ENGINE CONTROLS