W/ One Knock Sensor
NOTE: Idle speed, ignition timing and CO are interrelated and must be checked and adjusted together.THE FOLLOWING CONDITIONS MUST BE OBTAINED BEFORE ADJUSTING AND CHECKING THE IDLE CO% CONTENT AND IDLE SPEED.
1. Engine oil temperature must be at a minimum 176°F. (80°C.).
2. All electrical consumers must be switched off.
3. Radiator cooling fan must not cycle during checking and adjusting.
4. Air conditioning must be switched off.
5. Fuel Injection pressure testing gauge assembly must not be connected to the injection system.
6. If fuel injection lines were loosened or replaced, raise engine to 3000 RPM's several times to clear air from lines, before any adjustments are made
7. Exhaust system must be tight and free of leakage.
8. Oxygen sensor control system must be operating correctly.
9. Throttle valve in idle position.
10. Throttle valve switch OK.
11. Coolant thermo-switch OK.
Charcoal Canister Tee.:
12. Remove cap from charcoal canister tee.
Crankcase Breather Hose:
13. Remove crankcase breather hose at valve cover and plug with cap from charcoal canister tee.
14. Remove cap from CO test tube and connect hose from exhaust gas analyzer.
NOTE: Hose must fit securely over CO tap tube so there is no exhaust leakage.
Multimeter And VW 1315 A/2 Adapter:
15. Disconnect idle stabilizer valve harness connector and insert test adaptor VW 1315 A/2 or equivalent between idle stabilizer valve and harness connector.
16. Connect multimeter to the test adapter and set meter to the 2 amp range.
IDLE SPEED
1. Start engine and check idle speed, Idle should be:
Manual transmission 800 +/- 50 RPM
Automatic transmission 720 +/- 50 RPM
Idle Speed Adjusting Screw:
2. Adjust idle speed, if out of specification, by turning idle speed adjusting screw at throttle housing.
3. After idle speed adjustment, check idle stabilizer mA reading on multimeter, should be:
Idle stabilizer mA reading 430 +/- 20 fluctuating
NOTE: For more information on testing the Idle Stabilizer system, refer to Computers and Control Systems.
AIR/FUEL (CO%)
Adapter Connection For Checking OXS Duty Cycle:
1. Connect test adapter US 1112 to test connector, then connect test leads from multimeter to adapter. Depress % button on multimeter, start engine and let idle.
2. Observe OXS duty cycle, should read:
OXS duty cycle 25 to 65%
3. Observe CO content on Exhaust Gas Analyzer, should read:
CO content (OXS sensor connected) 0.3 to 1.2%
NOTE: If CO content is greater than 1.2% volume, but duty cycle is between 25 and 65% check the following:
a. Ignition system, repair as necessary.
b. Leaks in exhaust system, repair as necessary.
c. Defective fuel distributor, repair as necessary.
CO Adjustment Screw:
3. If CO% is out of specification, the adjustment plug must be removed from the top of the air flow sensor housing.
4. Switch off ignition, remove intake air boot from the air flow sensor.
5. Lightly center punch CO adjustment plug, drill 3/32" (2.5mm) hole in center of plug approximately 5/64" (4.0mm) deep.
NOTE: Do not hit CO plug with force or drive plug through air flow sensor housing.
6. Remove plug by screwing a sheet metal screw into hole and using pliers pull plug out, reinstall air boot.
Tool P377 Adjusting Duty Cycle:
7. Start engine and allow to idle, using tee wrench P377 or equivalent adjust the duty cycle by turning the CO adjusting screw. Adjusting specification are:
Duty cycle specification 50% +/- 8% fluctuating
NOTE: Do not push the adjustment wrench downward during adjustment, remove the wrench after each adjustment, then increase engine speed and allow to stabilize, then check CO value.
8. Recheck idle RPM, adjust if necessary.
9. Reconnect the hoses for the crankcase ventilation system and charcoal canister system. Then attach connector to the idle stabilizer and cap for CO test tube. Install new plug for adjustment screw opening.
IGNITION TIMING
Ignition timing is determined by the control unit map and feedback signals and is not adjustable. If ignition timing is out of specification, refer to Computers and Control Systems.
Timing specification: TDC
BASIC IGNITION TIMING
Flywheel Timing Mark:
1. Turn crankshaft to TDC using suitable tool.
Cam Sprocket And Valve Cover Alignment:
2. Align mark on camshaft sprocket with upper edge of valve cover gasket.
3. Remove the distributor cap, rotor, and dust shield.
4. Remove shear bolt and tab at distributor hold down clamp, by drilling and tapping the bolt out. Loosen distributor clamp.
Trigger Wheel And Distributor Housing Alignment:
5. Rotate distributor until marks on trigger wheel and distributor housing align. Tighten distributor clamp.