Honda Accord

of release

Repair and operation of the car

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The VTEC system - the general information and check of a condition of components

General information

The VTEC system is developed by specialists of the Honda company for the purpose of a possibility of dynamic management of installation of phases of gas distribution and extent of opening of valves. The engines equipped with this system are marked by the inscription VTEC formed on a cover of a head of cylinders. The corresponding number of a series of the engine (F23A1 or F23A4) is beaten out on the party of the block turned to a radiator.

Difference of the engines equipped with the VTEC system from the basic version consists only the principle of management of phases of gas distribution and features of the device of the valvate mechanism. The design of the reduced engine block set, the scheme of the organization of lubrication systems and cooling remain the same, is equal as the list, the device and arrangements of hinged units.

The onboard processor of a control system of the engine of the equipped VTEC models is capable to correct the moments of operation and extent of opening of inlet valves due to use of cams of the camshaft of various size and a form. Depending on the data arriving from the information sensor, the processor, either includes, or disconnects system.

The order of functioning of the VTEC systems of both types is defined by the following initial parameters:

a) Frequency of rotation of the engine (rpm);
b) Speed of the movement of the car (miles/h);
c) Output signal of the sensor of provision of a butterfly valve (TPS);
d) The current load of the engine determined by indications of the sensor of absolute pressure in the inlet pipeline (MAR);
e) Temperature of cooling liquid.

The camshaft is equipped with three cams of the drive of each of the inlet valves of the engine differing from each other in a form of a profile and height of rise by which duration and size of opening of the corresponding valves are defined.

At small turns of the engine secondary inlet valves work from own cams of the camshaft having very small rise and a peaked form (i.e. valves, in comparison with primary, are slightly opened only slightly and very much for a while), holding the sprayed fuel from consolidation in a head of cylinders. At the same time the good lower torque with high speed of reaction develops that defines excellent traction characteristics and high acceleration performance of the car. Primary cams at the same time function in the normal mode, creating turbulences of gas mixture in combustion chambers.

If there is a need for increase in return of the engine, secondary yokes are blocked through intermediate with primary special synchronizing pistons. The synchronizing pistons have the hydraulic drive with electronic control. When blocking yokes both inlet valves begin to open in the identical mode, and degree and duration of their opening are defined by a form of a cam of an intermediate yoke and have the increased value.

Secondary yokes cease to contact to own cams up to that moment as the system will not be disconnected. At the same time both valves open on full height and with the maximum duration, providing increase in turns and return of the engine.

Check of a condition of components

Check of some of the VTEC components demands removal of assembly of yokes (see the Section Removal, check of a state and installation of assembly of yokes).

Electromagnetic valve of management of VTEC blocking

PERFORMANCE ORDER

The refusal of functioning of the electromagnetic VTEC valve leads to record in memory of the block of self-diagnostics of a code of malfunction and to operation of a control lamp "Check the engine" (see the Head Engine management).

Malfunction of the electromagnetic valve or its filter is the most frequent cause of infringement of functioning of VTEC. Regular performance of change of motive oil and the filter will allow to avoid annoying refusals.

1. The electromagnetic valve of management of blocking of VTEC is located on the right in a back part of a head of cylinders (from a back partition of a motive compartment).

2. Check existence of conductivity between the socket of the electromagnetic valve and mass of a body. Resistance of 14 ÷ 30 Ohms has to take place; otherwise the electromagnetic VTEC valve is subject to replacement.

3. At the switched-off ignition disconnect the electrical wiring plait socket from the sensor switch of pressure of VTEC and check conductivity between two plugs of the sensor switch on the electromagnetic VTEC valve. Conductivity has to take place, otherwise replace the sensor switch.

4. Include ignition and measure tension between the plug of a blue-black wire of the sensor switch of pressure and weight. The required value makes about 12 V, otherwise it is necessary to check a wire on the site between the socket and RSM for existence of breaks or short circuit on weight.
5. Without switching off ignition, measure tension between pressure sensor switch electrical wiring plait socket plugs. Tension in 12 V has to take place, otherwise it is necessary to eliminate break of a brown-black wire.

6. Separate the electromagnetic valve and manually check freedom of movement of its plunger. At installation of the valve into place do not forget to replace sealing laying.

7. Completely remove assembly of the electromagnetic valve from a head of cylinders and check a condition of sealing laying and passability of the filter. Clean assembly and establish it into place, previously having replaced sealing laying.

Violation of passability of the mesh filter is the most probable cause of refusals of functioning of the VTEC system.

Yokes

PERFORMANCE ORDER

1. Bring the piston of the first cylinder into the provision of VMT of the end of a step of compression (see the Section Reduction of the Piston of the First Cylinder in the provision of the top dead point (TDP)). Uncover a head of cylinders (see the Section Removal and installation of a cover of a head of cylinders).

2. Press a finger on an intermediate yoke of a set of inlet valves of the first cylinder, - it has to move irrespective of primary and secondary yokes of assembly. Working in the same order, check serviceability of functioning of yokes of inlet valves of the remained cylinders (the corresponding pistons are transferred to provisions of VMT).

Proofreaders of valvate gaps

PERFORMANCE ORDER

1. Assemblies of four proofreaders are put in special pockets in a head of cylinders of the engine.
2. Separately take from a head of cylinders each of proofreaders.
3. Check serviceability of functioning of proofreaders by push-up of plungers a finger. The plunger has to start with an easy resistance, gradually increasing it in process of deepening, otherwise replace defective assembly.

The synchronizing assemblies

PERFORMANCE ORDER

1. After removal and dismantle of assemblies of yokes (see the Section Removal, check of a state and installation of assembly of yokes), take also components of the synchronizing knots (see below).
Components of the synchronizing VTEC assemblies:

a) Yoke of the drive of primary valve (primary yoke);
b) Yoke of the drive of the secondary valve (secondary yoke);
c) Intermediate yoke;
d) The synchronizing piston A;
e) The synchronizing piston B;
f) Distributive piston.
2. Check a condition of a distributive spring. Make sure that it did not burst and did not sink. In case of need make replacement.

3. Check all other components (yokes and the synchronizing pistons) for existence of signs of wear, attritions, zadir, traces of an overheat and other defects. Replace defective parts. Take an oil dispersion jet from the third holder of the camshaft, clean it and establish on the place (engines without VTEC).

4. Assembly is made as it should be, the return to an order of dismantle of components.

Gather components of assemblies of each of cylinders, fasten them with a rubber bandage, only after it establish on an axis (see the Section Removal, check of a state and installation of assembly of yokes).