Idle Adjusting
NoteIdle speed, ignition timing and OXS-duty cycle (CO value) must be checked and adjusted together.
^ The oxygen sensor must remain connected during testing or adjustment
Testing and adjustment conditions
^ engine oil temperature min. 80~C (176~F)
^ electrical consumers turned off (including radiator fan)
^ A/C off
^ fuel pressure measuring equipment not connected
^ if fuel lines were disconnected or replaced, bring up idle speed to 3000 rpm several times and let engine idle for at least 2 minutes
^ there must be no leaks in exhaust system
^ oxygen regulation OK
- clamp hose (1) of idle speed boost valve together tightly
- pull off crankcase breather hoses and place so that only fresh air can enter
^ hose (2) from intake manifold
^ hose (3) from air filter
^ remove "T" connection (4) from carbon canister at intake air boot
^ turn "T" piece 90~ and insert blank side with 1.5 mm (0.059 in.) restrictor into hole in intake air boot
Note
If car is not equipped with this type of connector, use part #026-133-382D or equivalent plug with 1.5 mm (0.059 in.) orifice.
Idle speed/ignition timing/OXS-duty cycle (CO value), checking/adjusting
Work sequence
- connect duty cycle meter VW 1367 or Siemens 451 for measuring ignition timing and rpm
- run engine at idle
- check ignition timing, and adjust if necessary
^ speed under 1000 RPM
^ checking specification: 4 - 8~ BTDC
^ Adjusting specification: 6 +/- 1~ BTDC
- check idle speed, if necessary adjust with idle adjusting screw (5)
^ checking specification: 800 - 1000 RPM adjusting specification: 900 +/- 30 RPM
CAUTION
Inductive pickup (on VW 1367) must NOT be connected.
- remove cap from CO measuring pipe and connect CO test equipment hose
CAUTION
Hose must fit tightly on measuring pipe, so that there are no exhaust leaks.