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8.3. System of catching of fuel evaporations (EVAP) - the general information, check of a state and replacement of components

Check of serviceability of functioning of a control system of an adsorber purge on models of 2.4 l

1 — the Delivery camera of the inlet pipeline
2 — the throttle Case
3 — To combustion chambers
4 — From the air cleaner
5 — the Electromagnetic valve of management of a purge (is normally locked)
6 — the Union A
7 — the Union B

8 — the Valve of management of a purge
9 — the Control valve
10 — the Air cleaner
11 — the Air duct
12 — the Blowing-off hose
13 — the Flowmeter (MB991700)
14 — the Coal adsorber


General information

Changes of atmospheric pressure and temperature of air lead to differences of relative pressure in the fuel tank. If the tank had an untight design, then with an excessive pressure the air which is inside filled with fuel evaporations would come to light.

The EVAP system accumulates the fuel evaporations accumulating in the path of a power supply system having tight execution during the parking and provides a conclusion them to the inlet highway for burning in the course of normal functioning of the engine. Improvement of system is made continuously in process of toughening of requirements imposed to environment protection.

As the receiver accumulating fuel evaporations it is used filled with granules of absorbent carbon a tight container, - a coal adsorber. The ventilating cover, the container providing a possibility of a purge by fresh air is provided in the top part of an adsorber. The fuel evaporations deleted from an adsorber at a purge come to the inlet pipeline and burn down in the course of normal functioning of the engine.


The special operating valve (the purge valve) provides an adsorber purge in a definite time under the corresponding service conditions of the engine. The valve has normally closed design (it is closed in the absence of food), functions under control of PCM and at disconnection of a chain of grounding provides giving on a depression adsorber.

In the course of warming up of the engine, and also for some time after implementation of hot start of PCM holds a contour of grounding of the valve closed. The purge of an adsorber is made only on reaching temperature of cooling liquid of value about 49 °C. During the operation of the engine on single turnover of PCM can carry out periodic locking of the valve for the purpose of corrections of composition of air-fuel mix.

For safety the cover of a jellied mouth of the fuel tank is equipped with the two-sided safety valve via which alignment of internal pressure in a tank of rather atmospheric is in case of need made.

On EVAP equipped with system of onboard diagnostics of the second generation (OBD-II) system failures are registered in the form of codes in the processor memory. Monitoring is carried out by means of the differential sensor of pressure and the sensor of intensity of a purge tracing an expense of the gas stream brought out of an adsorber in the engine which is built in in the fuel tank. The description of the principles of functioning of the OBD systems and the list of codes of malfunctions are given below in this Chapter.

Check

 PERFORMANCE ORDER

Full diagnostics of the EVAP system is among the procedures lying outside qualification of the average amateur mechanic and its performance has to be entrusted to specialists of car service. It is necessary to notice that additional federal guarantees extend to components of system. Most often failures of the system of EVAP are connected with damages of a coal adsorber or connecting lines.

1. Violation of stability of turns of idling, decrease in efficiency of return of the engine, spontaneous stops of the last can be caused by failure of the control valve, damage of a coal adsorber or connecting hoses of the EVAP system, and also the wrong laying of the last. Check also a condition of a cover of a jellied mouth of the fuel tank.
2. Obvious losses of fuel, as well as emergence of a strong smell of the last during the parking can be caused by leakages of fuel pipes, or damage of the case of a coal adsorber, malfunction of the control valve, a detachment, or violation of passability of vaporizing lines, and also the wrong laying of the last.
3. Check a state, a route of laying and reliability of connection of all hoses of the EVAP system. Make necessary repair or replacement. The damaged components.
4. Examine the adsorber bottom on existence of signs of development of leaks, in case of need make replacement, - track correctness of connection of hoses.
5. Check passability of the filter and control valve. The air given under low pressure blow an adsorber, - air moves through the tube going from the fuel tank and has to come out freely through the other tubes brought to assembly. The faulty adsorber is subject to replacement (see below).


Control system of an adsorber purge

Models 1990 ÷ of 1993 of the issue, except 2.0 l of DOHC equipped with the engine with a turbo-supercharging (1990 ÷ 1992)

 PERFORMANCE ORDER

1. Disconnect the vacuum hose marked with red strips from the throttle case and connect to it the manual vacuum pump.

2. Zakuporte the open union on the throttle case.

3. Wait for cooling of cooling liquid up to the temperature below 60 °C and at the engine working at single turns create depression of 376 mm of mercury in depth on the valve., - it has to be kept by valvate assembly reliably. The same picture has to take place on single turns and after warming up of the engine over 70 °C.
4. Now lift the frequency of rotation of the engine to 3000 rpm and repeat check before the expiration of a 3-minute interval, - depression should not be created. During the operation of the engine on the raised turns within more than 3 minutes the possibility of creation of depression has to be restored in the absence of the fact of its deduction.

If check is made at height of more than 2200 m above sea level, or at a temperature of soaked up air over 50 °C, leakage of depression will have places constantly.

5. At negative results of the check described above it is necessary to make replacement of the operating valve.


The models 1990 ÷ of 1992 of the issue equipped with the engine of 2.0 l of DOHC with a turbo-supercharging

 PERFORMANCE ORDER

1. Disconnect a purge hose from an inlet air duct and a zakuporta the last.
2. Connect the manual vacuum pump to a hose.
3. Wait for cooling of cooling liquid up to the temperature below 60 °C and at the engine working at single turns create depression of 376 mm of mercury in depth on the valve., - it has to be kept by valvate assembly reliably. At increase in turns to 3000 in a minute tightness of the valve also should not be broken.
4. Now warm up the engine up to the temperature of cooling liquid over 70 °C and repeat check: on single turns depression has to be kept reliably by the valve, with a frequency of rotation of the engine of 3000 rpm within the first 3 minutes a possibility of creation on the valve demanded again (376 mm of mercury.) depression has to be absent, then it has to be created instantly in the absence of the fact of its deduction.

If check is made at height of more than 2200 m above sea level, or at a temperature of soaked up air over 50 °C, leakage of depression will have places constantly.

5. At negative results of the check described above it is necessary to make replacement of the operating valve.


Models since 1994 of the issue.

 PERFORMANCE ORDER

1 Connect a flowmeter of the MB991700 type between a blowing-off hose and a coal adsorber.
2. Include neutral transfer (RKPP), or transfer the selector lever to situation "P" (AT). Switch off everything onboard consumers of the electric power and warm up the engine up to the normal working temperature (80 ÷ 95 °C).
3. Let's the engine work on single turns within 3 ÷ 4 minutes, then several times squeeze out a pedal of a foot brake, reading out indications of the measuring instrument. The required value makes 20 cm/sec.
4. If the result of measurement appears below the stipulated value, repeat check at the vacuum hose disconnected from an adsorber, - in case of need remove the reason of blocking of the last. If the detachment of a hose does not lead to the required increase in intensity of a purge, check passability of the union of its connection on the adsorber case, try to replace also electromagnetic and executive valves of management of a purge.
5. If intensity of a purge corresponds to face value, replace a coal adsorber.


Valve of management of a purge

The models 1990 ÷ of 1993 of the issue equipped with the engine of 2.0 l with a turbo-supercharging


 PERFORMANCE ORDER

1 Remove the valve of management of a purge of a coal adsorber installed to the right of the battery.

2. Connect to the vacuum union on the valve the manual vacuum pump.

3. Check tightness of valvate assembly: the valve has to begin to pass the air given to the union of connection to an adsorber only during creation of depression on it about 203 mm of mercury in depth.
4. Now connect the pump to the pressure head union of the valve and create depression of 399 mm of mercury in depth., - the valve has to remain tight.
5. The faulty valve is subject to replacement.


Electromagnetic valve of a purge of an adsorber of the EVAP system

Models 1990 ÷ of 1993 of the issue, except 2.0 l of DOHC equipped with the engine with a turbo-supercharging (1990 ÷ 1992)

 PERFORMANCE ORDER

1. Mark and disconnect two vacuum hoses from the electromagnetic valve of management of a purge.
2. Disconnect an electrical wiring from the valve.

3. Connect the manual vacuum pump to the connection union marked with red strips vacuum a hose on valvate assembly.

4. Create depression on the valve and check tightness of assembly when giving of tension for it from the battery and without is as follows: in the first case depression should not keep, in the second - has to.

5. Measure resistance between plugs of the contact socket of the valve. The required value makes 36 ÷ 44 Ohm at 20 °C.

6. The faulty valve is subject to replacement.


The models 1990 ÷ of 1992 of the issue equipped with the engine of 2.0 l of DOHC with a turbo-supercharging

 PERFORMANCE ORDER

1. Mark and disconnect two vacuum hoses from the electromagnetic valve of management of a purge.
2. Disconnect an electrical wiring from the valve.
3. Connect the manual vacuum pump to the connection union marked with red strips of a vacuum hose on valvate assembly.
4. Create depression on the valve and check tightness of assembly when giving of tension for it from the battery and without is as follows: in the first case depression has to keep, in the second - no.
5. Measure resistance between plugs of the contact socket of the valve. The required value makes 36 ÷ 44 Ohm at 20 °C.
6. The faulty valve is subject to replacement.


Models since 1994 of the issue.

 PERFORMANCE ORDER

1. Mark and disconnect vacuum hoses from the electromagnetic valve of management of a purge.
2. Disconnect an electrical wiring from the valve.

3. Connect the manual vacuum pump to the union A on valvate assembly.

4. Create depression on the valve and check tightness of assembly when giving of tension for it from the battery and without is as follows: in the first case depression has to keep, in the second - no.

5. Measure resistance between plugs of the contact socket of the valve. The required value makes 25 ÷ 44 Ohm at 20 °C.

6. The faulty valve is subject to replacement.


Removal and installation of components

Coal adsorber

 PERFORMANCE ORDER

1. Disconnect a negative wire from the battery.

If the stereosystem established on the car is equipped with a security code before disconnecting the battery make sure that you have the correct combination for input of the audio system in action!

2. In case of need the car also install to a poddomkratta it on props. Remove the right forward wheel and a loker of protection of his arch.
3. Having previously carefully marked, disconnect all vacuum lines from an adsorber.

4. Turn out fixing bolts / release clamps and remove assembly of an adsorber from the car.

5. Installation is made upside-down.


Electromagnetic valves

 PERFORMANCE ORDER

1. Disconnect a negative wire from the battery.

If the stereosystem established on the car is equipped with a security code before disconnecting the battery make sure that you have the correct combination for input of the audio system in action!

2. Carefully mark and disconnect vacuum hoses and an electrical wiring from the electromagnetic valve of management of an adsorber purge.

3. Remove the valve assembled with a basic arm and take it from a motive compartment of the car.
4. Installation is made upside-down.