Volkswagen Golf/Jetta 2 manual

Carburettor (1.6 & 1.8 litre engines) - adjustments
Fuel and exhaust systems - carburettor models / Carburettor (1.6 & 1.8 litre engines) - adjustments


Note: Accurate adjustment of the carburettor is only possible if adjustment of the ignition timing, dwell angle and spark plug gaps is correct. Incorrect valve clearances can also effect carburettor adjustment Pierburg/Solex 2E2
1 The adjustment procedures for the 2E2 carburettor closely follow those described for the 2E3 carburettor. The following checks and adjustments are additional to, or differ from, those given.

Part throttle channel heater unit 2 To check this unit, connect a test lamp between the unit wiring plug and battery positive terminal. Earth the unit. If the test bulb fails to light, the unit is defective and must be renewed.

Choke valve gap (wide open kick) 3 Remove the automatic choke cover and fit a rubber band to the operating pin, so that the choke valve is held in the closed position.

4 Hold the primary throttle valve open 45∞. To do this, temporarily insert a 10 mm nut between the fast idling adjustment screw and the vacuum unit plunger.

5 Using a twist drill, check that the gap between the choke valve and carburettor wall is 6.3 ± 0.3 mm. If not, bend the choke operating lever as required (see illustration).

17.5 Checking choke valve gap
17.5 Checking choke valve gap

Using drill of correct diameter as a gauge (arrowed) Note dimension x (10.0 mm)

6 After making an adjustment, check and adjust the choke pull-down unit as follows.

Choke pull down unit
7 This unit can be checked in the same manner as that for the choke pull down unit on the 2E3 carburettor but note that the resistance felt must be over the final 5.0 mm of travel.

8 Note also that from February 1987, the choke pull-down unit is both temperature and time-controlled by a thermotime valve. When the valve is open (starting a cold engine) the vacuum to the pull-down unit is reduced, and the choke valve will open by a small amount.

After between one and six seconds (depending on ambient temperature), the valve heats up (to approximately 20 to 30∞C) and closes. This allows more vacuum to reach the pull-down unit and the choke valve will open by a larger amount. The choke is of course fully released by the heat of the engine coolant and the electric heater acting on the automatic choke bi-metallic spring.

Accelerator pump
9 To make this check, the carburettor must be removed and you will need a vacuum pump and an M8 x 20 mm bolt.

10 Detach the vacuum hoses from the three/four point unit then connect up the vacuum pump to the three/four point unit at УAФ (see illustration). Plug connection B (and C on four point unit). Apply vacuum with the pump to hold the diaphragm pushrod in the overrun/cut-off position and to give a clearance between the fast idle speed and diaphragm pushrod.

17.10 Accelerator pump check preparation
17.10 Accelerator pump check preparation

A Vacuum pump connection B Plug vacuum connection (3-point unit) C Plug vacuum connection (4-point unit)

11 Pivot the warm-up lever up to the point where the throttle valve control pin has clearance and insert the M8 x 20 mm bolt to hold the warm-up lever in this position (see illustration).

17.11 Accelerator pump adjustment check showing warm-up lever (A) lever (B)
17.11 Accelerator pump adjustment check showing warm-up lever (A) lever (B) and bolt (C)

12 Hold the carburettor over a funnel and measuring glass then slowly open the throttle valve lever fully five times allowing at least 3 seconds per stroke. Divide the total quantity by five and check the resultant injection capacity against that specified.

13 If adjustment is necessary, loosen screw A and rotate the cam plate B in the required direction to increase or decrease the injection capacity (see illustration). On completion, retighten the screw and seal in position with locking compound.

17.13 Loosen screw (A) and turn cam plate (B) in direction required to adjust
17.13 Loosen screw (A) and turn cam plate (B) in direction required to adjust accelerator pump injection capacity

14 The accelerator pump injection capacity can also be checked with the carburettor in the vehicle but as specialised equipment is required, this is a task best entrusted to your VW dealer.

Throttle valve
15 For the basic Stage ll valve adjustment, proceed as described in Section 16, paragraphs 6 and 7 whilst referring to the accompanying illustration (see illustration).

17.15 Lock lever clearance with throttle valves closed
17.15 Lock lever clearance with throttle valves closed

Three/four point unit - vacuum pump method
16 Detach the vacuum hoses from the unit and attach a vacuum pump to connection У1Ф (see illustration). Apply vacuum to pull the diaphragm pushrod to the idle point and then measure the amount of rod protrusion, which must be as specified.

17.16 Three or four point unit check preparation
17.16 Three or four point unit check preparation

Pushrod to idle point a = 8.5 mm 1 Vacuum connection
2 and 3 Plug these connections

17 To check the overrun cut-off point, plug off the vacuum connection 3, then apply increased vacuum with the vacuum pump.

This should cause the diaphragm pushrod to move to the overrun/cut-off point. Measure the rod protrusion (a) which should now be 1.0 mm. The pushrod should hold at this position for one minute.

18 If rod protrusion is incorrect, or will not hold for the specified period, then the diaphragm or three/four point unit are probably leaking and in need of renewal.

Three/four point unit - engine vacuum method
19 Run the engine to normal operating temperature then switch it off. Remove the air cleaner and close the vacuum line from the carburettor to the temperature regulator.

20 With the engine stopped, check the diaphragm pushrod (A) (see illustration) is fully extended to approximately 14.5 mm.

17.20 Three/four point unit with pushrod (A) and cold idling adjusting screw
17.20 Three/four point unit with pushrod (A) and cold idling adjusting screw (B) in idling position

21 Start the engine and let it idle. The diaphragm pushrod must now be extended approximately 8.5 mm (three-point unit), or 9.5 mm (four-point unit), and must just contact the fast idle adjustment screw.

22 On models with air conditioning, switch on the air conditioner with the blower on maximum speed. The diaphragm pushrod dimension should be approximately 12.0 mm.

23 To check the overrun cut-off point, run the engine at idle speed.

24 On the four-point unit, disconnect and plug the pink-coloured hose at the control valve.

25 Using a screwdriver, hold the primary throttle valve fully closed to prevent it moving to the overrun cut-off point.

26 Disconnect the plug from the idling/overrun control valve, then check that the diaphragm pushrod dimension is approximately 1.5 mm.

27 To check the unit for leaks, first, on the three-point unit only, pinch the hose between the unit and Y-piece.

28 Stop the engine by disconnecting the coil terminal 15, and check that the diaphragm rod remains in the overrun/cut-off position for a minimum of five seconds.

29 Reconnect the coil wiring, control valve plug and hose where applicable. Refit the air cleaner.

Stage ll vacuum control unit 30 This device is fitted to 1.6 litre manual gearbox models and 1.8 automatic gearbox models from August 1984 on. Its function is to delay the Stage ll opening slightly whilst the coolant temperature is below 18∞C. It achieves this by venting the vacuum hose via the thermo-pneumatic valve and the resistor (see illustration).

17.30 Stage II vacuum unit control
17.30 Stage II vacuum unit control

1 Thermo-pneumatic valve 2 Restrictor
3 Straight connection hose

31 Check that the straight hose at connection 3 on the thermo-pneumatic valve is not blocked and check the valve itself by blowing through it. It should be open at 18∞C and close when the temperature rises above 28∞C.

Idle/overrun control valve 32 Entrust this operation to your VW dealer as specialised testing equipment is necessary.

Temperature time valve
33 Entrust this operation to your VW dealer as specialised testing equipment is necessary.

Slow running and fast idle 34 To check and adjust the slow running setting, proceed as described in Section 15, paragraphs 7 to 13 inclusive whilst noting the following differences:
a) Before making any adjustments, ensure that the three/four point unit pushrod is in the idling position with the cold idling adjusting screw touching the pushrod b) If adjustment is necessary, turn the idling speed control valve and CO adjustment screw (see illustrations), as necessary.

c) Access to the CO adjustment screw is gained by prising out the tamperproof plug. If the CO content is difficult to adjust, remove the adjustment screw and clean its point, then refit and adjust it

17.34a Idling speed control valve (A)
17.34a Idling speed control valve (A)

17.34b Mixture (CO) adjustment screw (A)
17.34b Mixture (CO) adjustment screw (A)

35 On automatic transmission models, the increased idling speed can be checked and adjusted as follows. In addition to those preliminary requirements necessary when checking the idle speed slow running setting, the hand brake must be fully applied and chocks placed against the wheels.

36 When the engine is started, turn on the fresh air blower (fully), switch on the headlights (high beam) and the heated rear window. Get an assistant to sit in the vehicle and depress the foot brake then select D. Check that the four point unit diaphragm rod is in the increased idling position, the fast idle adjuster screw rests against the diaphragm rod and the engine increased idle speed is not under that specified. Adjust if necessary by altering the regulator valve setting (see illustration).

17.36 Engine speed regulator valve (1)
17.36 Engine speed regulator valve (1)

37 On models fitted with air conditioning, the procedure for checking the increased idling speed is similar to that for automatic transmission models except that it is also necessary to switch on the air conditioner and have the control set at maximum cooling at the highest blower speed. The increased idle speed must be as specified and if adjustment is required, alter the regulator valve setting accordingly.

38 With the slow/increased running idle speed adjustment complete, the fast idle speed can be checked and, if necessary, adjusted. Check that the engine is still at its normal operating temperature.

39 Detach the Y-piece from the vacuum hose and plug the hose (see illustration). Connect a tachometer to the engine. Start and run the engine and check that the fast idle speed is as specified. If not, turn the adjustment screw on the linkage as necessary (see illustration). On completion of adjustment, apply sealant to the screw threads to lock it in position, unplug and reconnect the Y-piece to the vacuum hose and check that the slow running (idle) speed is as specified.

17.39a Disconnect and plug vacuum hose (1) to check/adjust engine fast idle
17.39a Disconnect and plug vacuum hose (1) to check/adjust engine fast idle speed adjustment

17.39b Fast idle adjustment screw (A)
17.39b Fast idle adjustment screw (A)


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