Ignition Timing: Adjustments

Adjusting Timing
(breakerless distributors)

You should adjust the ignition timing whenever the distributor has been removed and reinstalled or after installing a replacement Hall sending unit. Incorrect timing can cause decreased fuel economy and excessive exhaust emissions.

1. On vehicles with manual transmissions, use a special wrench (VW Tool US 4463) to remove the plastic plug from the timing check hole at the top of the transaxle's flywheel bellhousing.

Note: You must remove the entire plug by unscrewing it with a wrench that fits the hexagonal recess. You will not see the timing marks if you snap out only the small central plug which is tor the temporary insertion of a computer analysis sensor.

Fig 4-7:

Fig. 4-7. Tachometer correctly attached to breakerless distributor 1000 Ohm and 12,000 Ohm resistors can be obtained from a radio supply store.
Use 3 square mm (14 or 12 gauge) wire, and insulate resistors and connections with electrical tape.
2. Connect a tachometer as indicated in Fig. 4-7. Then, following the instrument manufacturer's instructions, install a stroboscopic timing light.
3. Start the engine and allow it to warm up until the oil temperature is at least 80°C (176° F). If the idle speed of a fuel injection engine sold outside California (no digital idle stabilizer) is not between 850 and 1000 rpm, adjust the idle.

Fig 4-8:

Fig. 4-8. Plugs (arrow) for digital idle stabilizer detached from stabilizer and connected to one another.
4. On engines with digital idle stabilizers, stop the engine. Then detach both plugs from the digital idle stabilizer and connect the plugs together as indicated in Fig. 4-8. (These plugs are present on some other vehicles, but they are connected together at the factory.)

5. On engines with carburetors, disconnect the vacuum retard hose only from the ignition distributor's vacuum unit and plug the hose. Locations
On 1984 models, clamp the idle bypass hose.
6. Start the engine and allow it to idle. Then check the idle speed. On 1980 through 1984 fuel injection models, except 1980 through 1982 California models, the idle speed should be between 850 and 1000 rpm; on 1980 through 1982 California models with fuel injection, the idle speed should be between 880 and 1000 rpm; on 1980 carburetor models, the idle speed should be between 800 and 1000 rpm. If not, adjust the idle speed.

Fig 4-9:

Fig. 4-9. The 7.5° BTDC mark on flywheel of 1980 carburetor engine correctly aligned with pointer in timing check hole. On 1982 through 1984 carburetor engines, set timing at 2° BTDC as marked.

Fig 4-10:

Fig. 4-10. The 6° BTDC mark on flywheel correctly aligned with pointer in timing check hole: applicable to all 1983 and 1984 U.S. cars with fuel injection engines and manual transmissions, and to 1983 Pickup Trucks sold in California with fuel injection engines and manual transmissions.

Fig 4-11:

Fig. 4-11. The 3° ATDC mark on flywheel correctly aligned with pointer in timing check hole on fuel injection engine used with manual transmission (except 1983 Pickup Trucks sold in California and 1983 and 1984 cars sold in the U.S., including California).

Fig 4-12:

Fig. 4-12. The 3° ATDC mark on drive plate of fuel injection engine used with automatic transmissions correctly aligned with pointer in large hole in bellhousing.
7. Aim the timing light at the timing check hole in the bellhousing. Illuminated by the timing light, the timing mark should appear stationary adjacent to the pointer in the hole. Time models with carburetors as indicated in Fig. 4-9. Time 1983 and 1984 cars sold in the U.S. with manual transmissions and 1983 Pickup Trucks sold in California with manual transmissions as indicated in Fig. 4-10. Time all other U.S. and Canadian models as indicated in Fig. 4-11 (manual transmission) or Fig. 4-12 (automatic transmission).

Fig 4-13:

Fig. 4-13. Flywheel with timing scale used on some 1983 and 1984 U.S. built models. Each mark equals 2°. Arrow indicated 6° BTDC.

Note Some 1983 and 1984 U.S. built Rabbits and 1983 Pickup Trucks have flywheels with timing scales (Fig. 4-13) instead of single timing marks. Some 1984 Rabbits with fuel injection and 5-speed transmission have an incorrect timing mark at 3° ATDC. Make a new mark at 6° BTDC (Fig. 4-10), 12 mm (0.47 in.) left of TDC.

8. If the timing mark is not correctly aligned with the pointer, loosen the ignition distributor's hold-down bolt. Then, with the engine idling between 800 and 1000 rpm, hand-turn the distributor housing clockwise or counterclockwise until the mark is aligned with the pointer.
9. Where applicable, reconnect the vacuum retard hose. The idle speed should drop by about 200 rpm into the idle speed adjusting range.
10. Stop the engine. On engines with digital idle stabilizers, disconnect the plugs from one another and reconnect them to the digital idle stabilizer.
11. On vehicles with digital idle stabilizers, restart the engine. Accelerate it to about 2000 rpm and then allow the engine to return to an idle. With the digital idle stabilizer connected, the rpm should stabilize between 850 and 950 rpm (1980 engines with carburetors), between 880 and 1000 rpm (1980 through 1982 engines with fuel injection), or between 850 and 1000 rpm (1983 and 1984 engines with fuel injection).
12. If necessary, stop the engine. Then disconnect the tachometer and the timing light.