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6.4. Information sensors

For additional information on an arrangement and diagnostics of the information sensors described in this Section address Heads the Power supply system and System of ignition.

Cooler temperature sensor

General description

The cooler temperature sensor (it is shown by an arrow) is usually located near temperature measuring instrument, near the regulator of pressure of fuel and represents a thermistor (the resistor which resistance changes according to temperature). Change of resistance defines power failure on the sensor. At low temperatures sensor resistance high. At temperature increase resistance falls. Refusals in a sensor chain in most cases happen because of weakening of contact of a wire or its short circuit; if problems with wires are not observed, check the sensor as it is described below.

Check

 PERFORMANCE ORDER

  1. When checking the sensor, first of all measure its resistance in a cold state (usually from 2100 to 2900 Ohms).
  1. Further start the engine and warm up it up to the normal working temperature. Resistance has to be lower (usually than from 270 to 400 Ohms).

If restrictive access to the sensor of temperature complicates connection to its contacts of electric probes, remove the sensor as it is described below, and make check in the container with the heated water imitating operating conditions.


Before this procedure wait for full cooling of the engine.

Replacement

 PERFORMANCE ORDER

  1. For removal of the sensor press a spring stopper, disconnect the electric socket, then carefully turn out the sensor. Be ready to an effluence of a small amount of a cooler; for reduction of an effluence prepare the new sensor and establish it as soon as possible.

Handle with the cooler sensor very with care. Damage of this sensor will influence work of all system of injection of fuel.


Before removal of the sensor can be required to merge a small amount of a cooler from a radiator.

  1. Before installation of the sensor be convinced that its carving pure and apply on it a small amount of a compound.
  2. Installation back to removal.

Sensor of concentration of oxygen

General description

Usually sensors of oxygen are installed on cars with the catalytic converter. The majority of sensors of oxygen are located in an exhaust pipe behind a final collector. On model 535 the sensor of oxygen is installed in the catalytic converter. The electric socket of the sensor for simplification of access is turned towards the forward panel (left side).


The oxygen sensor (it is shown by an arrow) is usually located in an exhaust pipe behind a final collector, traces concentration of oxygen in exhaust gases.

Oxygen in exhaust gases interacts with the sensor of oxygen and creates tension changing from 0.1 B (high concentration of oxygen, poor mix) to 0.9 B (low concentration of oxygen, rich mix). ECU constantly monitors this change of tension to define a ratio of oxygen and fuel in mix. ECU, operating duration of an impulse of opening of fuel injectors (opening time) changes the air relation / fuel mix. Fuel mix from 14.7 parts of air and 1 part of fuel is ideal mix for minimization of toxicity of the fulfilled gases, allowing the catalytic converter to work with the greatest efficiency. This relation 14.7 to 1 ECU and the sensor of oxygen try to support all the time.

The sensor of oxygen does not develop any tension if its temperature is lower than the normal worker about 320 °C. During this initial stage of warming up of ECU works in the mode of "an open contour" (that is, without information from the sensor).

When the engine gets warm up to the normal working temperature and/or worked within two or more minutes and if the sensor of oxygen develops constant tension below 0:45 In at 1500 rpm or big turns, memory of codes of refusals of ECU becomes more active.

If there is a problem with the sensor of oxygen or its chain, ECU works in the mode of "an open contour", that is it operates supply of fuel according to the programmed value of codes of refusals instead of information of the oxygen sensor.

The correct operation of the sensor of oxygen depends on four conditions:

  1. Electric - the Low voltage developed by the sensor depends on high-quality, pure contacts which it is necessary to check every time at suspicion or detection of misoperation of the sensor.
  2. Intake of external air - the Design of the sensor provides intake of air in an internal part of the sensor. Every time at removal of the sensor be convinced that air channels are not corked.
  3. The correct working temperature - ECU does not react to temperature sensor signals until it gets warm, approximately, to 320 °C. This factor has to be considered at assessment of operability of the sensor.
  4. Unleaded fuel - Use of unleaded fuel is essential to the correct operation of the sensor. Make sure that you apply such fuel.

In addition to the conditions given above special attention should be paid on service of the sensor.

Check

 PERFORMANCE ORDER

  1. Warm up the engine and leave it to idle. Disconnect the electric socket from the oxygen sensor and connect to output contact of the sensor the positive probe of the voltmeter (address the following table), and the negative probe - to the case. The oxygen sensor, being warmed up (to 320 °C), develops very small signal of tension. Usually tension of a signal is ranging from 0.1 to 1.0 B).

Versions of sockets of sensors of oxygen from a cable. For procedures of checks use the corresponding contacts of the sensor (there are three various four-wire sockets of sensors of oxygen - do not mix them).


Electric sockets of the majority of sensors of oxygen are located in a back part of the engine near the forward panel. Find a big rubber cover with a thick cable. On early models 535i the socket of a chain of the heater of the sensor of oxygen is under the car. Find a small protective cover. These models have to have own sensor of oxygen that access to it was analogous with other models. About additional information consult at the dealer.

  1. Tracing tension, increase, and then reduce engine turns.
  2. At increase in turns tension has to increase up to 0.5 - 1.0 Century. At decrease in turns tension has to decrease up to 0 - 0.4 Century.
  3. If it is applied, examine the oxygen sensor heater (models with multiwire sensors). At the included ignition disconnect the electric socket of the sensor of oxygen and connect to the contacts specified in the table (see below), the voltmeter. Between contacts there has to be battery tension (approximately, 12 V).
  4. If indications wrong, check the oxygen sensor heater relay (watch the Head Sistem of onboard electric equipment). If information on the relay is inaccessible, determine an exact arrangement of the relay of the heater of the sensor of oxygen by the management for the owner of the car. On the relay tension of the rechargeable battery has to arrive.
  5. If the sensor of oxygen does not undergo at least one of this testing, replace the sensor.

Replacement

Due to that: that the sensor is installed in a final collector, the converter or a pipe which contract when cooling, the sensor of oxygen can appear very difficult to turn out on the cold engine. Instead of risking to damage the sensor (if you plan to use it in other collector or a pipe again), start the engine and let's work minute or two, then muffle it. Do not burn when performing the following procedure.


 PERFORMANCE ORDER

  1. Disconnect a negative wire of the rechargeable battery.

If the radio receiver on your car is equipped with system of protection against stealing, before shutdown of the rechargeable battery be convinced that the correct code of activization is known. Before a detachment of a wire apply for information to the Section System of Protection of the Audio System from theft and language of an instrument guard.


If after connection of the battery on the display of the dashboard the message in other language appears, for the procedure of installation of language address the Section System of Protection of the Audio System from theft and language of an instrument guard.

  1. Lift the car and install it on supports.
  2. Disconnect the electric socket from the sensor.
  3. Carefully unscrew the sensor.

Excessive the effort can damage a carving.

  1. For simplification of the subsequent removal it is necessary to apply a high-temperature anticorrosive compound on a carving of the sensor. The carving of the new sensor is already covered with such compound, but if the old sensor acts and installed, then apply a compound on a carving.
  2. Install the sensor and hardly tighten it.
  3. Attach the electric socket of a cable of the sensor to the main cable of the engine.
  4. Lower the car and connect the battery.
Oxygen sensor type Output signal of the sensor Power supply of the heater (12 V)
Not warmed up (single-wire) black wire () no
Warmed-up (three-pro-water) contact 1 () contacts 3 () and 2 (-)
Warmed-up (four-pro-water) contact 2 () contacts 4 () and 3 (-)

Sensor of provision of a throttle (TPS)

General description

The sensor of provision of a throttle (TPS) is located on the end of a shaft of a throttle in the throttle case. Tracing the output tension of TPS, ECU can define on the basis of knowledge of an angle of rotation of the valve of a throttle fuel supply (set by the driver). In this TPS system works as the switch, than as a potentiometer to a large extent. One group of contacts of the switch of the valve of a throttle is closed (connection of contacts) only idling. The second group of contacts becomes isolated at full opening of a throttle. Between these provisions both groups of contacts are opened (there is no connection). The spoiled or weakened TPS can cause unstable injection of fuel and unstable turns of idling as ECU will decide that the throttle moves.

All models (except early models 535i with automatic transmission) have the integrated switch of idling and a full throttle; the separate switch of idling indicates a closed position of a throttle while TPS is used for designation of a full open throttle. On models 535i with automatic transmission of TPS it is connected directly to the control unit of automatic transmission. At completely open throttle the control unit of transmission sends a signal of an open throttle to Motronic control block.

All models, except early 535i with automatic transmission

Check

TPS of the L-Jetronic system is located under the inlet pipeline (contacts are shown).

 PERFORMANCE ORDER

  1. Disconnect the electric socket from TPS and connect the 2 and 18 ohmmeter to contacts. Check short circuit between contacts 2 and 18 at the closed throttle (the late Motronic system is shown).
  1. Slightly slightly open a hand a throttle. Slowly release a throttle that to a stopper there were 0.2 - 0.6 mm. The ohmmeter has to show short circuit.
  1. Check resistance between contacts 3 and 18 at an open throttle. There has to be a short circuit within 8-12 degrees from completely open situation. If indications wrong, adjust TPS.
  1. If all indications of resistance correct and TPS is correctly adjusted, check power supply of the sensor (5 V) and if necessary see wires between the sensor and ECU (watch the Head Sistem of onboard electric equipment).

Adjustment

 PERFORMANCE ORDER

  1. If adjustment does not conform to requirements (item 1-2), weaken TPS screws and turn the sensor in the correct situation. Follow the procedure of check of TPS given above and, having finished adjustment, tighten screws.
  2. Double-check TPS; if indications correct, attach the TPS cable socket.

Early models 535i with automatic transmission

Check

 PERFORMANCE ORDER

  1. At first check TPS short circuit. For check of short circuit perform procedures of item 1-2.
  2. Further check the switch of provision of idling. Disconnect the socket of a cable of the switch of provision of idling and connect the 1 and 2 ohmmeter to contacts. There has to be a short circuit. Slightly slightly open a throttle and measure resistance. Short circuit should not be.

The switch of provision of idling and TPS on early models 535i with automatic transmission.

  1. Check correctness of signals of output tension of TPS at the closed throttle and the included ignition. Connect the voltmeter probe to contact 3 (a black wire) from the back party of the TPS socket and check tension concerning the case. There have to be 5 V. Takzhe, check tension between contact 3 (a black wire) and contact 1 (a brown wire). Here too there have to be 5 Century.
  2. Check tension between contact 2 (a yellow wire) and contact 1 (a brown wire) and slowly open a throttle. Tension has to increase constantly from 0.7 B (the throttle is closed) to 4.8 B (the throttle is completely open).

Adjustment

 PERFORMANCE ORDER

  1. First, measure the stabilized tension. At the included ignition and completely closed throttle measure tension between contact 3 (a black wire) and contact 1 (a brown wire). It has to make about 5 Century.
  2. Further, weaken screws of fastening of the sensor and connect between contact 2 (a yellow wire) and contact 3 (a black wire) the voltmeter. At completely open throttle rotate the switch until tension does not become on 0.20 - 0.24 In less the stabilized tension.

Measurement of such little changes of tension will require the digital voltmeter.

  1. Double-check TPS; if indications correct, attach the electric socket to TPS. Expediently paint or a compound for fixing of carvings to stop TPS screws.

Air stream measuring instrument

General description

The measuring instrument of a stream of air is located in an inlet air duct. The measuring instrument of a stream of air measures amount of the air coming to the engine. ECU uses this information for management of fuel supply. A large amount of air means acceleration while the small amount of air means delay or idling. Concerning all diagnostic checks and procedures of replacement for the measuring instrument of a stream of air address the Head the Power supply system.

Ignition moment sensors

The ignition moment in the Motronic systems copes in the electronic way and is not subject to adjustment. At start the sensor of provision of a bent shaft transmits a signal to ECU and the initial point of the moment of ignition is defined by it. When the engine works, the ignition moment continuously changes depending on various entrance signals in ECU. Turns of the engine are defined by the RPM meter. In the early Motronic systems the reperny sensor and the RPM meter are installed over a flywheel on a coupling case. In the late Motronic systems there is a uniform sensor (the sensor of impulses) installed over a pulley of a bent shaft. This sensor works as the RPM meter and as the situation sensor. Apply for additional information to the Head Sistema of ignition.

Some models are equipped with the VMT sensor in a forward part of the engine. This sensor belongs to the block of service testing of BMW and is not a part of system of ignition of Motronic.