Audi 80/Avant (B4)

since 1991-1995 of release

Repair and car operation

Audi 80/Avant
+ Technical specification
+ Engines
+ System of production of the fulfilled gases
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and airintaking channels
+ injection System
+ Coupling
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrosystem
- Ignition system
   Various systems of ignition
   Principle of work of ignition
   Executive body
   System "brain"
   Impulses for the control unit
   Regulation on a detonation
   Security measures at work with ignition system
   Repair of system of ignition
   Diagnostics of system of ignition
   Ignition distributor
   Sensor of detonation combustion
   Elements of a high voltage
   Replacement of spark plugs
   Spark plugs
   Check of the moment of ignition
+ Lighting
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
+ Specifications

Replacement of spark plugs

The plan of servicing provides each 30 000 km replacement of spark plugs. This interval is represented to us real and to prolong it it is not necessary. It is necessary to watch closely serviceability of system of ignition, especially on the cars equipped with catalytic converter, – we already spoke about it. But nevertheless it is necessary to look at the removed candles attentively: it is specified below, about what to you can tell a deposit on a spark plug.

By the way, if you removed candles for control in an interval between replacements: hands they are better be not to cleaning. It will damage an insulating layer of an average electrode of a spark plug (стеатит). However between electrodes you can check a gap.

Removal of spark plugs


  1. To pull together tips of spark plugs from contact probes of candles. Not to pull wires!
  2. To turn out spark plugs and to put according to sequence of cylinders that on a condition of a candle it was possible to draw conclusions on a condition of the corresponding cylinder.
  3. If candles are difficult turned out, do not apply force, differently the carving in a head from an easy alloy can break.
  4. Warm up the engine and now turn out candles.
  5. At installation it is impossible to roll cold candles in the hot engine, then they will need to be turned out.
  6. Spark plugs it is necessary to tighten the moment of 20 N • m. If near at hand there is no dinamometrichesky wrench:
  7. To screw a candle to a prileganiye of a sealing ring – in this case it it is impossible to turn more neither a hand, nor a candle key without the use of force.
  8. Now, if you established new candles, tighten a candle key still approximately on a turn quarter.
  9. If you put already used candles, will be enough if you turn a candle key approximately on 15 °.

 Helps: in order that it is easier to screw and subsequently to turn out a candle, you can put a little graphite from a soft pencil on a carving or a little copper greasing. Oil or usual plastic greasing lead to a spark plug prikipaniye in a carving of a head of the block of cylinders.

The defective carving of a spark plug is at all a reason for despair! The workshop will put in this case the special carving plug (for example Heli-Coil insert).

Deposit on candles

Spark plugs in a sense this word are witnesses of combustion in the engine. Appearance of spark plugs allows to define (deposit), whether the engine optimum works. Previously it is necessary to warm up thoroughly the engine on a country road or the highway. Control after a short distance can lead to the wrong conclusions. Look at a tip of a cone of an insulator with an average electrode and lateral electrodes.

  • The tip of a cone of an insulator has gray or brownish color: well adjusted system of injection, the engine works economically.
  • Strong deposits: additives in engine oil or fuel, or the raised consumption of oil can be the reason. Probably, it is necessary to change oil or fuel brand.
  • Black sazheobrazny deposits: the spark plug because of frequent trips on short distances does not reach self-cleaning temperature, the wrong kalilny number.
  • The tip of a cone of an insulator has brown color: too early moment of ignition, does not function electronic regulation of the moment of ignition or the sensor of detonation combustion.
  • Traces of oplavleniye on an average and lateral electrodes: the kalilny ignition caused by deposits in the chamber of combustion, peregrety nozzles, the wrong moment of the ignition which has been brought down by the moment of ignition, the faulty sensor of detonation combustion or an engine overheat.
  • The insulator cone is broken, in an initial stage is distinguishable as a thin crack: detonating combustion because of the bad fuel, incorrectly adjusted ignition, the brought-down moment of ignition, the faulty sensor of the detonation combustion, insufficient cooling of the engine or mix pauperization because of hit of unrecorded air.
  • Oil layer on electrodes and an internal surface of a spark plug: the damaged piston rings, directing valves or maslosjemny caps of valves.
  • If on a surface of a spark plug there are no specified signs, however the engine is all the same slowly started or works with interruptions, the reason nevertheless can be covered in candles. Invisible cracks in a ceramic insulator can be filled during cold start with being condensed fuel because of what there is a leakage of a spark. Candles can refuse at operation though the spark is visible when the candle is removed.

Gap between electrodes

The fuel and air mix, and also products of combustion have korrizionny impact on metal electrodes of spark plugs. And the high voltage at a proskakivaniye of a spark pulls out parts of metal because of what in operation the gap between electrodes increases. The following indicators of a gap between electrodes of spark plugs are admissible:

  • 4-and 5-cylinder engines: 0,7 — 0,9 mm
  • 6-cylinder engines: 0,9 — 1,1 mm

At the three-electrode candles which were applied in Audi 80 the igniting spark can «choose to itself» respectively the shortest spark interval. Therefore hardly it is required to turn in an electrode in addition.