The throttle body contains the throttle plates which controls the amount of air flowing into the engine. The throttle plate is connected to the accelerator pedal via a cable on all models except the 5 Series with traction control. The 5 Series cars that have traction control have a system called EML, translated into English is Electronic Motor Load regulation.
EML is a system that controls the throttle not by cable, but by an electric servo motor. A sensor on the accelerator pedal feeds information about throttle position to the EML controller. The EML controller tells the servo motor on the throttle body how far to open the throttle plate. Because of the electronic control, there is no need for a separate cruise control actuator, for a transmission control cable or for a throttle cable. The only connection to the throttle body is a multi-pin electrical connector.
The procedure to perform the external safety path check requires a special BMW tool 12 7 010 or equivalent. Do not attempt any repairs on an EML related part without having access to the tool.
The only throttle body adjustments that can or should be done are on the S14 engines. The other engines are equipped with throttle bodies that need no adjustments. The S14 engine throttle body adjustments should be performed only if the throttle bodies were disassembled or damage occurred.
Special tools needed for these procedures include feeler gauges, dial indicators, dial indicator mounts, and vernier calipers. The settings are very precise and require familiarity with the tools being used.Axial Clearance
- The measurements used in this procedure are based on the ambient temperature being 68°F. (20°C.).
- Close the throttle plates. Check that the throttles move easily.
- Check that a 0.008 inch (0.2mm) feeler gauge can fit between throttle body housing and the snapring or throttle lever.
- Check for damage or warpage if the feeler gauge does not fit.
- Open the throttle plates to the full open position.
- Measure the distance from the top edge of the throttle plate to the top of the throttle bore. The measurement should be 0.854 inch (21.7mm).
- If the measurement is not correct, loosen the locknut on the screw mounted in the middle of each throttle housing, between the throttle bores. Move the screw to achieve the correct measurement. Do not change the length of the throttle linkages.
- If there is any deviation from the measurement, it should be evenly shared by each of the throttle housing.
- The throttle lever pushrods must be check and adjusted for length. On the S14 engine, the pushrod for cylinders 1 and 2 should be 3.937 inch (100mm) and the pushrod for cylinders 3 and 4 should be 3.822-3.854 inch (97.1-97.9mm).
- Install the pushrods and align the levers. Loosen and move the clamps to obtain alignment.
- Install a dial indicator on cylinder 3 and 4 throttle lever. Adjust the cylinders 1 and 2 pushrod until movement is noted on the dial indicator. The throttle levers are adjusted when they evenly hit the idle speed stop.
Checking External Safety Path
This procedure must be completed anytime a component of the EML throttle by wire system is removed or disconnected. It requires tool 12 7 010 or equivalent. Do not work on any EML component without having access to this tool.
- Turn the ignition switch to OFF . Unplug the EML connector. The EML connector is grouped with the DME engine connectors. The EML connector is next to the engine diagnostic connector, centered in the group of 3 circular connectors.
- Install the EML testing adapter 12 7 010 or equivalent to the EML connector inline. Make sure all connections are tight.
- Turn the knob on the tester to the left position and start the engine. Adjust the engine speed to 2500 rpm with the tester knob.
- Depress the brake pedal. The engine speed should drop immediately due to the overrun shutoff provision.
- If the engine speed does not drop immediately, check the EML system for faults. If the speed does drop immediately, the EML external safety path is functioning.
- Shut off the engine and remove the tester.
Removal & Installation
Except S14 Engine
- On the M20 engine drain the coolant to below the level of the throttle body.
- Turn the ignition switch to the OFF position.
- Remove the intake air duct from the throttle body. If equipped with EML, remove the multi-pin connector.
- Disconnect the throttle cable, the transmission cable and the cruise control cable. Mark and disconnect the vacuum lines and the air hoses. Move the idle speed control valve out of the way. Disconnect the coolant hoses on the M20 engine.
- Remove the mounting nuts and remove the throttle body.
- Clean the mating surfaces of the throttle body and the intake manifold. Install a new gasket and the throttle body. Torque the mounting nuts to 6.5-8.0 ft. lbs. (9-11 Nm).
- Connect the hoses, vacuum lines and air hoses to the throttle body. Replace the idle speed control valve.
- Connect the throttle cables or EML connector. Install the intake air duct.
- Turn the ignition switch to the OFF position.
- Remove the cap nuts holding the intake manifold to the throttle bodies. Disconnect the throttle cable and the air hoses. The crankcase breather hose will have to be cut off. Remove the intake manifold.
- Disconnect the harness from the throttle switch. Remove the fuel injector electrical plug plate from the injectors.
- Remove the vacuum hose from the fuel pressure regulator. Remove the 2 mounting bolts and remove the fuel rail complete with the fuel injectors.
- Disconnect the nut holding the throttle linkage. Remove the Torx®nuts holding the throttle bodies to the cylinder head. Remove the throttle bodies.
- Separate the throttle bodies if necessary.
- If any components on the throttle bodies or linkage have been disturbed, they will have to be adjusted for proper operation.
- The throttle body gaskets may be reused if there is no damage to the ridge around the gasket opening. Use a thin bead of silicon sealer around the opening ridge. Replace the gasket if there is any damage.
- Attach the throttle bodies and check the condition of the connecting pipe O-ring for damage. Replace if necessary.
- Install the throttle bodies to the cylinder head with the new or used gasket. Torque the mounting nuts to 6.5-8.0 ft. lbs. (9-11 Nm).
- Connect the throttle linkage with a new locknut. Replace the fuel injectors and fuel rail. Torque the mounting nuts to 6.5-8.0 ft. lbs. (9-11 Nm).
- Install the fuel injector electrical plug plate and the throttle switch connector.
- Check the intake manifold O-rings and replace if necessary. Install a new crankcase breather hose. Install the intake manifold, air hoses and throttle cable.