Audi A4

since 1994 of release

Repair and car operation



A4 Audi
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ exhaust System
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and absorption channels
- Injection system
   + System of injection of Motronic
   - System of injection of MPI and MPFI
      Additional functions
      Knots of system of injection
      Functioning
      Adjustment with the help a lambda probe
      Violations in work and self-diagnostics
      Self-help
      Visual control
      Check of knots
      Dismantle of separate details
      Butterfly valve cable
      Inlet collector
      Idling adjustment
      Check of exhaust gases
      The help at malfunctions
+ Coupling
+ Transmission and main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
+ Electrotechnical equipment
+ ignition System
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ body Details
+ Salon
Search of malfunctions
Technical characteristics





Check of knots

In the following sections checks of elements of system of injection, possible with use of amateur means are described.

Injection valves

If there is a suspicion that one of valves of injection does not function, you can easily find out it by means of the light-emitting diode indicator of tension and an exact ohmmeter.

 PERFORMANCE ORDER

  1. Dismantle an engine cover.
  2. Disconnect sockets of valves of injection.
  3. In the beginning tension check: connect the light-emitting diode indicator of tension (not a control lamp) to socket contacts. Start the engine: the light-emitting diode in the indicator of tension should flash, if is not present, tension does not move or the control unit connecting weight, is faulty. This check cannot be carried out the measuring device.
  4. Resistance check: disconnect sockets of valves of injection, connect an ohmmeter to both contacts of the valve: if the engine cold, the device shows 13,5–17 Ohm.
  5. If the size is not tolerant, replace the valve (if measurement was carried out precisely).
  6. Tightness check: dismantle a distributive tube of fuel together with injection valves.
  7. Sockets of valves of injection are disconnected, топливопроводы remain connected.
  8. Let your assistant several times will turn the engine a starter in order that earned the fuel pump and there was a pressure of fuel.
  9. Observe injection valves: each of them should let out at most 1-2 drops of fuel in a minute. Otherwise replace the corresponding valve.
  10. Irrespective of it it is possible to check a stream of injection and amount of fuel injected by the valve if it is necessary because of violations in operation of the engine.

Butterfly valve potentiometer

 PERFORMANCE ORDER

  1. Disconnect the socket of a potentiometer of a butterfly valve.
  2. By exact ohmmeter measure resistance between potentiometer contacts.

Provision of a butterfly valve
Measurement between contacts
Nominal size (kiloohm)
Has no value
1 and 2
1,5–2,6
Idling
2 and 3
0,75–1,3
Full gas
2 and 3
at most 3,6

Having disconnected the socket (1), it is possible to measure tension giving on valves of injection (2) by means of the light-emitting diode indicator of tension. When the engine is turned by a starter, light-emitting diodes in the indicator of tension should flash. If is not present, tension does not move.

Measuring instrument of weight of air

Only MPI

On the right: in the photo are shown a measuring instrument of weight of air (1) engine with working volume of 2,8 l and the three-polar socket (2).

At the left: the scheme of an arrangement of contacts of the three-polar socket is used for check of a measuring instrument of weight of air.


 PERFORMANCE ORDER

  1. Measurements are made at a butterfly valve in the situation "idling" and «full gas» at the idle engine.
  2. The following nominal sizes should be received:
  3. Shift back a rubber tip on the socket of a measuring instrument of weight of air, the socket remains connected.
  4. Connect the exact voltmeter to socket contacts behind how it is described below:
  5. Measurement 1: connect measuring wires to contacts «2» and «3».
  6. Include ignition.
  7. The voltmeter should show 12–14 V.Esli is not present, defect in tension giving.
  8. Check a safety lock 32 if it is necessary, check a wire from a safety lock 32 to contact «3» sockets of a measuring instrument of weight of air.
  9. Or check connection from weight of the engine to contact «2».
  10. Measurement 2: connect measuring wires to contacts «1» and «2».
  11. Include ignition.
  12. The voltmeter should show 0,3–1,1 Century.
  13. Start the engine (the wire remains connected). Switch off everything consumers, the fan of a radiator should not work
  14. l Consistently force to hesitate engine turns between idling and 4000 rpm.
  15. The voltmeter should show (depending on number of turns) from 1,5 to at most 3,4 V.Esli is not present, the measuring instrument of weight of air is faulty. Replace it.

Valve of stabilization of idling

Only MPI

With working volume of 2,8 l the valve of stabilization of idling is in the engine on the right on a butterfly valve branch pipe.

 PERFORMANCE ORDER

  1. Disconnect the socket of the valve of stabilization of idling and connect an exact ohmmeter to both contacts of the socket of the valve.
  2. The measuring device should show 7–11 Ohm, otherwise the valve is faulty.
  3. Deeper check of working capacity: dismantle the valve of stabilization of idling; the socket remains connected.
  4. Rotor in air pass of the valve put in situation "is open" or closed" (do not use for this purpose the metal tool).
  5. Include ignition and observe a rotor: it should fluctuate approximately on the average situation.
  6. Check ease of a course of a rotor: it should move at the expense of tolchkoobrazny movement of the dismantled valve.
  7. Besides, on it there should not be jags or attritions.

Valve of stabilization of idling

Only MPFI

In the photo the valve of stabilization of idling (shooter) in the engine with working volume of 2,6 l is shown.


The valve of stabilization of idling (1) with working volume of 2,8 l is in the six-cylinder engine near a regulator of pressure of fuel (2) as you can see in this photo.


 Attention! The valve of stabilization of idling of the engine with working volume of 2,6 l cannot be dismantled in a house workshop as right after installation so-called main adjustment of system of injection should be carried out that it is possible to make only by means of the device for reading of malfunctions of V.A.G 1551 in Audi workshop.

If the socket on the valve of stabilization of idling is disconnected within 1/2 hours after the last switching off of the engine, malfunction «defect of the valve of stabilization of idling» will be kept in memory of the computer (that, maybe, was not made before).

In this valve the winding is checked only:

 PERFORMANCE ORDER

  1. Disconnect the socket on the valve of stabilization of idling.
  2. By exact ohmmeter measure resistance between socket "1" and "4" contacts, and also «2» and «3» valves.
  3. If the valve in working condition, the device has to show 45–60 Ohm, otherwise the valve it is necessary to consider defective.
  4. By own efforts it is impossible to carry out other checks.
  5. If the workshop replaces the valve, at once carries out the mentioned main adjustment.

The sensor of temperature of cooling liquid of system of ignition/injection

At the left: behind on the engine screwed up in a tube of supply of cooling liquid there is a combined sensor of temperature of cooling liquid (1) system of ignition/injection and the temperature indicator. Here the socket (2) is disconnected for sensor check. Socket "1" and "3" contacts belong to system of injection.

On the right: the chart shows, at what temperature what size of resistance this sensor should show.


 Attention! If the socket on the sensor of temperature of cooling liquid in the engine with working volume of 2,6 l is disconnected within 1/2 hours after the last switching off of the engine, malfunction «defect of the sensor of temperature of cooling liquid» will be kept in memory of the computer (that, maybe, was not made before).

General provision: the reason can be in the sensor of temperature of cooling liquid if in certain ranges of temperature there are shortcomings of operation of the engine. Check:

 PERFORMANCE ORDER

  1. Disconnect the socket on the sensor of temperature of cooling liquid.
  2. Measure by an ohmmeter resistance between contacts of the socket "1" and "3" of the sensor.
  3. The measured resistance is compared depending on engine temperature to the chart of nominal size below. If the size is at considerable distance out of curves, replace the temperature sensor.
  4. In summary here it is necessary to call two more rough sizes of resistance: at temperature of cooling liquid of 20 °C the ohmmeter should show about 2,5 kiloohms, at 80 °C – about 330 Ohm.

The sensor of temperature of soaked-up air

Only MPFI

On the right: the sensor of temperature of soaked-up air (3) is only in the engine with working volume of 2,6 l. It is on the right behind on the engine near the valve of stabilization of idling (1) and a regulator of pressure of fuel (2).

At the left: on this chart the size of resistance of the sensor depending on temperature of soaked-up air is shown.


 Attention! If the socket on the sensor of temperature of soaked-up air is disconnected within 1,5 hours after the last switching off of the engine, malfunction «defect of the sensor of temperature of soaked-up air» will be kept in memory of the computer (that, maybe, was not made before).


 PERFORMANCE ORDER

  1. Disconnect the socket of the sensor of temperature of soaked-up air.
  2. Measure by an exact ohmmeter resistance between two contacts of the socket of the sensor.
  3. Compare the measured resistance depending on engine temperature to nominal size in the chart below. If the size is at considerable distance out of curves, replace the temperature sensor.
  4. In summary here the rough size of resistance is specified: at 20 °C (room temperature, the engine cold) the device should show about 6,3 kiloohms.