Mercedes of the S-class W202

1993-2000 of release

Repair and operation of the car

Mercedes W202
+ 1.2. General information
+ 2. Maintenance
+ 3. Engines
+ 4. Lubrication system
+ 5. Cooling system
+ 6. Heating, ventilation
+ 7. System of ignition
- 8. Fuel system
   + 8.1.1. Introduction
   - 8.2. System of injection of petrol engines Principle of work of PMS Principle of work of HFM
      8.2.2. Self-diagnosing of a condition of system of ignition and injection of fuel
      8.2.3. Air flowmeter
      8.2.4. Thermal sensor of cooling liquid
      8.2.5. The sensor of the soaked-up air
      8.2.6. System of vacuum pipelines
      8.2.7. The fuel distributor with valvate nozzles
      8.2.8. Valvate nozzles
      8.2.9. Oxygen sensor (lambda probe)
      8.2.10. Diagnostics of malfunctions of system of injection of gasoline
      8.2.11. What should be known to the owner of the car with the injector engine
      8.2.12. Turbo doctor
   + 8.3. System of injection and power supply of diesel engines
   + 8.4. System of production of exhaust gases
+ 9. Transmission
+ 10. Running gear
+ 11. Steering
+ 12. Brake system
+ 13. Body
+ 14. Electric equipment
+ 14.2. Electrical circuitries Principle of work of PMS


1,8 / 2,0 l engines

The scheme PMS – systems of injection of fuel (the 1,8 / 2,0 l engines)

36. The thermostat (only at type 124)
40. Membrane regulator of pressure
41. A membrane quencher of pressure (only at type 124)
55. Fuel filter
60. System of the modulating pressure of the membrane mechanism of the vacuum regulator of an advancing of ignition (only in the presence of an automatic box peredy)
75. Fuel tank
77. A tank with absorbent carbon
82. The pipeline under depression
156. Inlet gas pipeline
158. Catalyst
159. Final collector
A1r5. Indication of temperature of cooling liquid
B11/3. Thermal sensor of cooling liquid
B17. The thermal sensor of the soaked-up air
G3/2. Oxygen sensor
K3/1. System of partial heating of the inlet gas pipeline (only at type 124)
K27. Relay of the fuel pump
L5. Position sensor of a bent shaft
M3. Fuel pump
M16/6. Executive body of system of regulation of frequency of rotation of a shaft of the engine when idling
N3/6. Control unit engine (PMS)
N6. Control unit conditioner
N30. ABS control unit
R16/7. The leveling shtekkerny socket
R33. WITH - a potentiometer, only at cars without catalyst (abroad)
S2/1. Switch of ignition and starter
S16/1. Switch of blocking of inclusion of a starter and switch of headlights of a backing
T1/1. The coil of ignition 1 for cylinders 1 and 4
T1/2. The coil of ignition 2 for cylinders 2 and 3
W14. A weight point on the holder of the hydraulic block of the ABS system
X4/10. Connecting block
X11/14. The central plug for connection of the diagnostic stand
X12/3. The plug 30/15 of a connecting block without safety lock
Y62. Valvate nozzles


Instead of the thermostat (36) and the regeneration valve (51), the type of engines 202 (S-class) is equipped with the switching valve which directly is run by the PMS control device.

Fuel from the fuel tank is soaked up by the electric fuel pump and moves to valvate nozzles via the fuel filter and the distributive pipeline. Pressure regulator on the distributive pipeline supports to constants pressure in fuel system depending on depression in an inlet pipe. Valvate nozzles cope electric systems, and injection of fuel is carried out periodically, pushes in an inlet pipe in front of inlet valves. At the same time valvate nozzles cope poluposledovatelno, i.e. on each turn of a bent shaft at the same time alternately injects respectively two valvate nozzles. At malfunctions in system of ignition for protection of the catalyst the corresponding group is disconnected.

Air is sucked in by the engine via the air filter and the inlet gas pipeline. Depression in the inlet gas pipeline is registered a sensitive element and serves as criterion of amount of the let-in quantity. As depression depends on the provision of a butterfly valve (the provision of a pedal of an accelerator), the amount of the let-in air is criterion of the actual loading of the engine. Therefore this control system is called R-management where "Р" is the physical quantity of pressure.

The control system according to depression and this frequency of rotation of a shaft of the engine regulates injection time and by that amount of injectable fuel. At rather long opening of a valvate nozzle more fuel is injected. The additional sensor and executive links in extreme road situations care also about respectively the measured amounts of fuel.

The actuation device of system of injection of fuel regulates the frequency of rotation of a shaft of the engine in the idling mode by means of its control point adjustment which regulates amount of air in the idling mode around a butterfly valve. Thanks to it the constant frequency of rotation of a shaft of the engine in the idling mode is reached irrespective of whether direct additional consumers, such as the steering mechanism with the amplifier or the conditioner compressor are connected.

1. Multicontact plug (lateral face of the car)
2. The multicontact plug (on the party of the engine)
83. The pipeline to the inlet gas pipeline which is under depression
R16/7. The leveling plug for fuel coordination
X12/3. The plug 15 of a connecting block without safety lock

The control unit the engine (N3/6) is in a motor compartment on the left side.

The relay of the fuel pump (27) powers electricity the fuel pump. The safety scheme interrupts giving of current as soon as any more rotation frequency impulses do not arrive, for example, if the engine was stopped. The relay is located in a luggage carrier on the right side; 1 – rechargeable battery.

The oxygen sensor (lambda probe) measures the content of oxygen in a stream of exhaust gases and sends the corresponding signals of tension to the actuation device. After that the actuation device so regulates injectable amount of fuel that the fulfilled gases optimum are burned up on the catalyst.

The thermal sensor of the let-in air takes its temperature, the second thermal sensor on the case of the regulator of supply of cooling liquid changes temperature of the last.

The electromagnetic valve for aeration of the fuel tank is operated depending on power setting. The emitted vapors of fuel are caught by the filter with absorbent carbon and via the valve move on combustion. Therefore, thanks to the filter filled with absorbent carbon, fuel vapors mostly economically are used and do not get to the atmosphere.

On a flywheel (1) and on an inlet driving gear wheel of the camshaft inductive sensors (L5) are installed. They transfer information on the actual frequency of rotation of a shaft of the engine and a position of a bent shaft to the actuation device of system of injection of fuel.

The system of ignition has no moving elements of a design any more and therefore up to spark plugs it is not subject to wear. If in a motor compartment to disconnect (to pull together) the leveling shtekkerny socket, then it is possible to fuel more poor quality. If you refuel gasoline for cars with the high-forced engines again (octane number 96–98, not less than 95 ROZ), then again spread the leveling shtekkerny socket.