The throttle valve regulator is an electro-pneumatic regulator controlled by the carburetor control unit and, in accordance with this, regulates the position of the throttle valve in a certain range. The range of regulation extends from high idle speed to full throttle closing, that is, to shutdown in forced idle mode and to engine shutdown. The regulator pusher is adjacent to the throttle lever and can be moved under the influence of a vacuum membrane. Overcoming the resistance of the regulator return spring. The required operating pressure is regulated by 2 solenoid valves, one valve supplies the intake manifold vacuum and the other the atmospheric pressure. Depending on the state of the valves, determined by the control unit, the pressure applied to the membrane, and hence the position of the pusher, continuously changes.
As soon as the driver gives gas, the idle switch in front of the pusher closes and thus informs the control unit about the departure of the throttle lever from the pusher.
Withdrawal
Remove air filter (see section «Removal and installation of the air filter»).
Disconnect the vacuum hose and breather tube from the throttle valve control.
Disconnect the connector by first folding out the fixing bracket.
Disconnect the idle switch connector.
Loosen 3 nuts (arrows) and remove the throttle control.
Installation
Screw on the throttle valve adjuster, slightly tightening the screws with a torque of 3 Nm. and make basic adjustments.
Basic adjustment
Unscrew stop screw -1- for tappet from throttle lever and replace with a new screw.
Disconnect the temperature sensor connector and bridge the connector contacts with a piece of wire.
Apply a negative pressure of approx. 250 mbar via the connection -U- of the throttle valve control. The vacuum must be kept constant.
Turn on the ignition.
Screw in stop screw -1- for tappet until the special tool BMW 131110 can move between positive idle stop and positive idle stop screw with tension. In this case, the throttle control should not function. Finally, separate the screw head from the pusher stop screw -1-.
Connect the idle switch and throttle control connector and secure with the retaining clips.
Connect the vacuum hose and vent tube to the throttle control.
Install air filter (see section «Removal and installation of the air filter»).
Check idle speed and CO content. Setpoint see table in section «Ignition system».
Examination
The test is carried out in the removed state.
Leak test
Apply battery voltage to terminals 2 with auxiliary wires (+) and 3 (-): This opens the solenoid valve.
Connect an ohmmeter to terminals 4 and 7.
Apply vacuum to connection -U- of throttle valve control; in this case, the membrane retracts the pusher, overcoming the force of the spring. Raise the vacuum with a vacuum pump until the ohmmeter reading increases from 500 to 700 ohms.
Then remove the wire from terminal 3. This closes the valve.
Detach vacuum hose from connector -U-.
The ohmmeter reading must not change more than 200 0m within 1 minute, otherwise replace the throttle valve regulator.
Stroke and response time check
Apply a negative pressure of approx. 250 mbar via the connection -U- of the throttle valve control. The vacuum must be kept constant.
Apply battery voltage to terminals 2 (+) and 3 (-). In this case, the pusher must quickly retract within a maximum of 1 second.
Attention: Behind the fitting -U- there is a backstop bug that prevents the penetration of fuel vapors into the electric valve.
Disconnect the wire from terminal 3 and switch off the vacuum pump.
Measure distance -E- (drawing W-2009). In this case, do not operate the idle switch.
Apply ground to terminal 8. This allows air to enter the throttle valve and the push rod should pop out within a maximum of 1 second.
Measure the distance to the throttle body.
If the response time or stroke differs from the values given in the Carburetor Basic Data Sheet, replace the throttle control.
Checking the idle switch
Connect an ohmmeter to the idle speed switch connector. When you press the switch, the resistance should be 0, in the opposite state - infinity.
Throttle controller resistance test
Check the resistance of the vacuum valve by connecting an ohmmeter to terminals 2 and 3.
Check the air valve resistance by connecting an ohmmeter to terminals 2 and 8.
Check the total resistance of the potentiometer by connecting an ohmmeter to terminals 4 and 5.
Check the resistance of the engine by connecting an ohmmeter to terminals 4 and 7. After that, slowly sink the pusher; while the resistance should decrease. Measure the resistance with the plunger fully recessed.
If the resistance values deviate from the specified values, replace the throttle valve regulator. For set values, see table of basic carburetor technical data.