Fuel Injection System - Throttle Valve Check/Adjust (GROUP 24, NO. 85-01)
Publication date: 1985-05-31Reference number: GROUP 24, NO. 85-01
FUEL INJECTION SYSTEM - THROTTLE VALVE CHECK/ADJUST
TECHNICAL SERVICE BULLETIN
FUEL INJECTION SYSTEM - IDLE SPEED SPECIFICATIONS - THROTTLE VALVE SWITCH - VACUUM HOSE LAYOUT - HEATER, CRANKCASE VENTILATION
Model(s): 1985 Volkswagen Vanagon
Group: 24 - Multiport Fuel Injection
Bulletin No.: 85-01
Part Identifier: N/A
Date: May 31, 1985
SERVICE INFORMATION
| Application/ Model Year | Idle Stab. Control Unit Identification/Test Connections | Idle Speed Rpm |
|---|---|---|
| California & Canada1983-85 | green, 251 906 083 control unit by-passed control unit connected | 850 +/- 50 900 +/- 50 |
| 49 States 1983-84 | green, 251 906 083 control unit by-passed control unit connected | 850 +/- 50 900 +/- 50 |
| 49 States 1985 | black, 321 906 083 control unit by-passed control unit connected | 750 +/- 80 800 +/- 50 |
THROTTLE VALVE SWITCH
FUNCTION
With throttle valve "closed", switch signals control unit about the following:
- Idle injection quantity
- Switching off injection during deceleration
When throttle valve "open", switch signals control unit about the following:
- Full throttle injection quantity
THROTTLE VALVE SWITCH, CHECKING/ADJUSTING
Connect ohmmeter across terminals of unplugged switch connector 1. See Fig 1 .
- Ohmmeter must read 0 ohms only when throttle lever is at idle stop and full throttle stop.
- Check switch-on point of throttle switch as follows.
Open throttle valve and slowly close.
Measure switch-on point with feeler gauge between idle stop and idle adjusting screw.
- Must be 0.05-0.10 mm (0.002-0.004 in) before idle stop (gap a). See Fig 1 .
IF MEASUREMENT NOT OK
Correct by adjusting position of switch. Loosen screw 2 and adjust screw 3. See Fig 1 .
- Gap "a" too large. Engine surges with lean condition.
- Gap "a" too small. With cold engine, stalling at full throttle acceleration. With engine warm, no deceleration fuel shut-off.
CONTROL UNIT AND WIRING, CHECKING
WORK SEQUENCE
Switch ignition ON.
Using voltmeter, check voltage present across terminals of connector 2. See Fig 2 .
If voltage reading is NOT OK
Check for open circuit in wiring.
If wiring is OK
Replace control unit.
DECELERATION FUEL SHUT-OFF, CHECKING
TEST CONDITIONS
- Temp. sensor II minimum 60°C (140°F) with resistance reading less than 550 ohms.
WORK SEQUENCE
Using end of tool VW 1490, bridge terminals of connector "2". See Fig 3 .
Accelerate engine slightly.
- Engine rpm must fluctuate (deceleration fuel shut-off system operates).
If rpm DOES NOT fluctuate
Replace control unit.
FULL THROTTLE ENRICHMENT, CHECKING
TEST CONDITIONS
- Temp. sensor II minimum 60°C (140°F).
- CO tester and tachometer connected.
Start engine and let idle approx. two minutes.
Slowly accelerate engine until 4000 rpm is reached.
- CO must read 0.3 - 1.1% Vol.
Using end of tool VW 1490, bridge terminals of connector 2. See Fig 3 .
- CO reading must increase above 1.5% Vol.
If CO readings NOT OK
Replace control unit.
THROTTLE VALVE SWITCH, REMOVING/INSTALLING
WORK SEQUENCE
Remove throttle body.
Remove switch 4 following numerical sequence of components 1 through 5. See Fig 4 .
Install components in reverse order.
Perform basic adjustments as follows.
THROTTLE VALVE, BASIC ADJUSTMENT
WORK SEQUENCE
Turn adjusting screw (arrow) out until gap exists between stop and screw.
Turn screw in until it touches stop.
Turn screw clockwise additional 1/2 turn. See Fig 5 .
Check idle speed and CO; adjust if necessary.
VACUUM HOSE LAY-OUT
Refer to Fig 6 .
HEATER, CRANKCASE VENTILATION (CANADA ONLY)
WORK SEQUENCE
Install with stamped on heater pointing toward vacuum source and electrical connector 3 angled approx. 60° to right. See Fig 7 .
CHECKING
Switch ignition ON.
Using voltmeter, check voltage across terminals of connector 4.
Unplug connector 4 from heater connector 3. See Fig 7 .
- Must be approx. battery voltage.
Using ohmmeter, check resistance across terminals of connector 3. See Fig 7 .
- Must be 7-14 ohms at approx. 25°C (77°F).