Deceleration Fuel Shutoff

Deceleration fuel shutoff can be checked by activating the idle switch while the engine speed is greater than a specified rpm. Decel fuel shut-off switches on when the engine speed greater than about 2150rpm and the idle switch is closed.

1. Ensure engine is at normal operating temperature (engine oil temperature 176°F minimum) and idle and full throttle switches are operating properly.
2. Start the engine and allow to idle.. Actuate the throttle switch while raising the engine speed to between 2150 and 4000 RPM.
3. Engine speed must fluctuate (engine surges and deceleration fuel shutoff switches on).
4. If engine speed does not fluctuate, proceed as follows:

a. Disconnect engine coolant temperature sensor connector, then bridge terminals of connector using bridge side of tool VW 1490 or equivalent.
b. If engine surges, replace coolant temperature sensor.
c. If engine does not surge, reconnect coolant temperature sensor and check wiring to temperature sensor and/or throttle switches.
d. If the wiring is sound, replace the Digifant II control unit.