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4.21. Functioning check, adjustment and replacement of the air valve of stabilization of idling

The air system of stabilization of idling provides maintenance of turns of idling within the range of 200 rpm, irrespective of change idling of load of the engine. For increase in turns of idling every time when their size falls lower than, about, 750 rpm, the electric valve which provides direct giving of a small amount of air bypassing the throttle valve is used. If turns of idling increase, about, higher than 950 rpm, the air valve of stabilization of turns of the course is closed and stops supply of additional air bypassing the throttle valve, that reducing idling turns.

The L-Jetronic systems it is equipped with the separate block of control of turns of idling (computer) located under the dashboard. The air valve of stabilization of idling has the adjusting screw. Early models are equipped with plastic valves, however, they also have adjustment for what it is necessary to disconnect a hose and to insert inside very thin screw-driver.

The early Motronic models are also equipped with the separate block of control of turns of idling (computer), located under the dashboard. The air valve of stabilization has the adjusting screw.

On the late Motronic systems the air valve of stabilization is operated from ECU and adjustment is not provided.

Preliminary check

Before performance of any checks of the air valve of stabilization of idling be convinced that the following conditions are satisfied:

Before any electric connections it is necessary to switch off ignition.

The air valve of stabilization of turns of idling at the included ignition continuously works. Start the engine and be convinced that the valve vibrates and slightly hoots.

L-Jetronic system

Check

 PERFORMANCE ORDER

  1. On the working engine disconnect the electric socket from the valve. Turns of idling have to increase, approximately, up to 2000 rpm.
  1. If turns of idling do not increase, kill the engine. Check an ohmmeter resistance between contacts of the valve. At ambient temperature about 20 °C resistance has to be from 9 to 10 Ohms.
  1. By means of two crossing points give tension of the rechargeable battery on the valve and be convinced that the valve is densely closed. At removal of tension the valve has to open.
  2. If the air valve of stabilization of idling does not maintain at least one of checks, then it should be replaced.
  3. If the vacuum valve of stabilization of idling maintains checks, check current of management.
  4. Disconnect the electric socket from the valve. Connect a crossing point one contact of the electric socket with one of contacts of the valve. Connect between other contact of the electric socket and the remained contact of the valve the ampermeter (with a range from 0 to 1000 мА). Start the engine and leave to idle. On the working engine current has to make size between 400 and 500 мА. If this size does not conform to requirements, adjust the valve (watch item 1).

Current of the stabilizer of idling changes between 400 and 1100 мА when the engine too cold if the cooler temperature sensor is faulty if adjustment of turns of idling is required if in the engine there is a leak of vacuum or if the additional electric equipment is switched on.

  1. If current is absent, send the control block idling turns for diagnostics to the dealer of BMW or other expert.

The block of control of the stabilizer of idling (located under the dashboard) can work with mistakes because of the electric socket which periodically connects and switches-off the valve. Before replacement of any parts carefully check the socket. Sometimes the new block of control will only temporarily fix a problem.

Adjustment

 PERFORMANCE ORDER

  1. At switched off ignition connect a tachometer according to the instruction of the manufacturer.
  2. Be convinced of correctness of installation of the moment of ignition (watch the Head Sistem of ignition).
  3. Connect the ampermeter to the valve (watch item 6).
  4. On the working engine current has to make 450-470 мА at 850-900 about / mines (manual transmission) or 460-480 мА at 850-900 rpm (automatic transmission).
  1. If current of management does not conform to requirements, rotate the adjusting screw that the size of current became correct.

On metal valves the adjusting screw is installed outside. On plastic valves the adjusting screw is located in and for access to it it is necessary to disconnect a hose from the valve.

Motronic systems

Check

In this system two types of air valves of stabilization of turns of idling are applied; early models are usually equipped two with the wire valve while late models are equipped with three-wire valves.


 PERFORMANCE ORDER

  1. Disconnect on the working engine from the valve the electric socket. Turns of idling have to increase up to 2000 rpm.
  2. If turns of idling did not increase:
    • The two-wire valve - give Two crossing points on the valve tension from the rechargeable battery and be convinced that it is dense to close the valve. At removal of tension the valve has to open. Also check valve resistance (see the drawing below). Resistance has to make about 9-10 Ohms.
    • The three-pro-water valve - Kill the engine and disconnect the electric socket from the valve. Check an ohmmeter resistance between two extreme contacts of the valve. It has to make about 40 Ohms.
  1. Check resistance between central and external contacts of the valve. They have to make about 20 Ohms.
  1. If the air valve of stabilization of idling does not pass any of checks, replace the valve.
  2. If the air valve of stabilization of idling undergoes all testing, then check current of management (the two-wire valve) or tension (the three-pro-water valve) as follows.
  3. At two-wire valves connect an ohmmeter (with a range from 0 to 1000 мА) as it is described in item 6. Start the engine and allow it to idle. On the working engine current has to be in limits 400-500 мА. Adjust the valve. if indications do not conform to requirements.

Current of the stabilizer will change from 400-1100 мА if the engine very cold if the cooler temperature sensor is faulty if in the engine there is a leak of vacuum or if the additional electric equipment is switched on.

  1. If there is no current, the idling control block (under the dashboard) it is necessary to send for check to the dealer of BMW or other expert.
  1. At three-wire valves check tension on the electric socket. At the included ignition at the central contact there has to be tension of the rechargeable battery. Between central and each of extreme contacts there has to be tension about 10 Century.
  1. If there is no tension, send the idling control block (early models) or ECU (late models) for check to the dealer of BMW or other expert.

Adjustment (only early models)

 PERFORMANCE ORDER

  1. At the switched-off ignition connect a tachometer according to the instruction of the manufacturer.
  2. Make sure that the moment of ignition is determined correctly (watch the Head Sistem of ignition).
  3. Connect the ampermeter to the valve as it is described in item 6.
  4. On the working engine current has to make 450-470 мА at 700-750 about / min.
  5. If current size wrong, rotate the adjusting screw, will not begin to meet requirements yet.

At rotation of the screw of the air valve clockwise current increases, against an hour hand - decreases.

Replacement

 PERFORMANCE ORDER

  1. Disconnect the electric socket and an arm from the air valve of stabilization of idling. Remove the valve, disconnect hoses.
  2. Installation back to removal.