Renault Megane, Scenic

Since 1996 of release

Repair and car operation

System of preheat of the diesel engine

The description

ENGINE F8Q 620

The system consists of the candles of heat screwed in vortical chambers, the block of the management established on a partition in an impellent compartment, and the gauge of temperature of the cooling liquid, the thermostat attached to a casing.

Candles накаливания eat from the block of management which also copes the electromagnetic valve of fast idling (on models with air conditioner) and the valve recycling the fulfilled gases (address to an accompanying illustration).

In need of preheat it begins at the moment of inclusion of ignition and partially proceeds till the moment of full warming up of the engine as follows.
At ignition inclusion the control lamp on the instrument panel lights up and a food on candles накаливания, dependent on temperature of a cooling liquid moves. (If the gauge of temperature of a cooling liquid is defective, candles automatically запитываются for 14 seconds). In the second phase after the control lamp will go out, power supplies giving on candles накаливания within 8 seconds proceeds, or the engine will not be started yet. Candles накаливания eat continuously while the starter works.
After the engine start, all candles накаливания receive a current even 10 seconds. Further food giving depends on temperature of a cooling liquid and engine loading. Heat temporarily stops, if the management block receives a signal of "maximum load" from the microswitch on the fuel pump, and renews, if microswitch contacts are disconnected again. Heat is disconnected completely when the temperature of a cooling liquid reaches 65°С, or in 30 seconds if the gauge of temperature of a cooling liquid is defective.

ENGINES F8Q WITH ТУРБОКОМПРЕССОРОМ

The preheat system copes the same block ECU which supervises the injection moment, fast idling and рециркуляцию the fulfilled gases. The block operates the relay of candles накаливания, and is located in an impellent compartment.
At ignition inclusion the control lamp on the instrument panel lights up and a food on candles накаливания, dependent on temperature of a cooling liquid and height above sea level (the management block contains the height gauge) moves. After deenergizing of a control lamp, food giving on candles накаливания within 8 seconds proceeds, or the engine will not be started yet. Candles накаливания eat continuously while the starter works.
After the engine start, all candles накаливания receive a current even 10 seconds. Further food giving depends on temperature of a cooling liquid, turns and engine loading. Heat temporarily stops, if the management block receives a signal of "maximum load" from a potentiometer of the lever of gas on the fuel pump; also renews, if loading again decreases. Heat is disconnected completely when the temperature of a cooling liquid reaches 65°С, or in 190 seconds.

ENGINES F9Q

The preheat system copes block ECU of system of the injection, established in the right forward part of an impellent compartment, about the fuel filter.
At ignition inclusion the control lamp on the instrument panel lights up and a food on candles накаливания, dependent on temperature of a cooling liquid moves. (If the gauge of temperature of a cooling liquid is defective, candles automatically запитываются for 14 seconds. After the control lamp will go out, power supplies giving on candles накаливания within 8 seconds proceeds, or the engine will not be started yet. Candles накаливания eat continuously while the starter works, but not longer 20 seconds and while temperature of a cooling liquid - more low 60°С.
After the engine start, all candles накаливания receive a food depending on temperature of a cooling liquid and engine turns. Heat stops temporarily if engine turns are exceeded by 2500 rpm, and absolutely if the temperature of a cooling liquid exceeds some certain value.

CHECK

1. At malfunction occurrence in system, serviceability check finally is reduced to replacement by obviously serviceable blocks, but some preliminary checks it is possible to execute as follows. 2. Attach the voltmeter or a control lamp pressure 12В between feeding cable of a candle накаливания and the earth (the engine or a car body). 3. Ask the assistant to include ignition and be convinced that pressure of a food moves on candles накаливания. Notice time during which the control lamp, and a total time during which pressure before system switching-off moves will burn. Switch off ignition. 4. At temperature in an impellent compartment 20°С average time should be the following: the control lamp should burn within 5-6 seconds and after it will go out, a food on candles should move still during 4 - 5 seconds (if the starter is not included). The control lamp will longer burn at smaller temperature, and on the contrary. 5. If there is no food in general, the relay or the connected electroconducting are faulty. 6. To define a defective candle накаливания, disconnect a power cable of a food and attach a wire piece to the central clip of a candle накаливания. Be cautious, do not drop a nut and a washer. 7. Check up resistance between each plug of a candle накаливания and the earth. Resistance of a serviceable candle накаливания very low (it is less than 1 Ohm) and if the tester shows high resistance, накаливания is necessary to replace a candle. 8. If the ampermeter is accessible, it is possible to measure a current consumed by each candle накаливания. After initial splash till 15-20 And, the candle should consume a current nearby 10А. If the candle consumes much more a smaller current, it is probable it is defective. 9. For final check, a candle накаливания it is possible to remove and examine as Removal, survey and installation of candles накаливания is described in Section.

ENGINE F8Q 620

The block of management of preheat - engine F8Q 620

Socket And + the accumulator: a constant food Socket In 1 — a Food candles накаливания 1 and 3 2 — a Food candles накаливания 2 and 4 Socket With А1/S2 — The Electromagnetic valve of management of pressurisation А2/РС — The Signal from the microswitch on the gas lever А3/CTN — The Signal from the gauge of temperature of a cooling liquid	In 1 / + АРС — a positive food Operated ignition В2/DEM — A starter Signal В3/Tem — Management of a control lamp of heating (through the earth) С1/S1 — It is not used С2/-Bat — Weight С3/Clim — The management Mechanism the electromagnetic valve of turns of fast idling during preheat

CHECK

1. If malfunction of the block of management the subsequent actions depend on what of following signs are present is suspected: a) the Control lamp of heat on the instrument panel does not work. b) the Control lamp of heat is lighted for short time. Absence of a mode of fast idling when the engine is not heated-up (models with air conditioner). d) the Engine сбоит (it is difficultly started from a cold condition, unstably works after start. 2. If the control lamp of heat does not burn, disconnect a socket From"the management block. Close a socket of a control lamp (contact В3/Tem) with the earth, using a safety lock 2А (address to an illustration above). Include ignition. If the safety lock fuses, means in electroconducting of a control lamp in the instrument panel there is a short circuit, and it is necessary for eliminating. If the safety lock does not fuse, but the lamp does not light up, means the lamp has fused, or its electroconducting is defective. 3. Then check up giving of a positive food of the accumulator (+ВАТ) on a socket "And", giving of management by ignition (В1 / + Ars) on a socket "With" and the accumulator earth (С2/-Bat) on a socket "With". If everything is all right, but the problem remained, replace the block of management with preheat. 4. If the control lamp of heat lights up quickly only at the moment of inclusion, disconnect a socket "In" and again include ignition. If the control lamp lights up now also pressure is present on socket exits "In", check up a chain of candles накаливания (address to paragraphs above). If malfunction in a chain is not found out, check up candles накаливания (address to Section Removal, survey and installation of candles накаливания). If the control lamp lights up, but on socket exits "In" there is no pressure, replace the block of management with preheat. If the control lamp lights up only for seconds, check up giving of a positive food of the accumulator on a socket "And". 5. If there is no mode of fast idling when the engine is not heated-up, include air conditioner. If fast idling works now, check up a socket From"the block of management of preheat. Check up, that there was no electroconducting breakage between contact С3/Clim of a socket"With"and contact of 1 socket of the electromagnetic valve. If breakage is not present, replace the block of management with preheat (be convinced that the control lamp is serviceable). If the mode of fast idling does not join even at operation of the valve of fast idling, restore a chain between the vacuum pump, the electromagnetic valve and the vacuum motor. If the valve does not open, check up pressure between two contacts of its socket. In the presence of pressure 12В, replace the electromagnetic valve, preliminary having checked up a socket condition. If no pressure is present, check up a chain between contact 2 sockets of the valve and the earth. 6. If the engine сбоит (it is difficultly started, roughly works in an idling mode, etc.), check up the main feed circuit of the block of management of preheat (a socket "And"), giving of a positive food operated ignition (a socket "With") and the earth on contact С2/-Bat of a socket "With". Check up also a current in a socket of the fuel pump. 7. Check up resistance of the gauge of temperature of a cooling liquid (address to Specifications). Check up adjustment and functioning of the microswitch of preheat (address to Section Adjustment, check, removal and installation of the microswitch of heat). 8. If after these checks the engine on former сбоит, address to the expert in diesel engines.

ENGINES F8Q WITH ТУРБОКОМПРЕССОРОМ AND F9Q

CHECK

28 For check of system of heat the special device (Renault XR25) which joins in diagnostic муфту is required. By means of this device it is possible quickly and to define easily a malfunction site in system, reading out the codes of the malfunction which have been written down in memory of the computer.