Honda Accord

1998-1999 of release

Repair and operation of the car

VTEC system - the general information

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 an inscription of VTEC formed on a cover of a head of cylinders. All V6 engines used to a complete set of the considered models of cars are equipped with VTEC system.

Difference of the engines equipped with VTEC system from the basic version consists only in principle managements of phases of gas distribution and features of the device of the valvate mechanism.

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 a 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 VTEC system 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 a 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. Thus the good lower torque with high speed of reaction that defines excellent traction characteristics and high acceleration performance of the car develops. Primary cams thus function in the normal mode, creating turbulences of gas mixture in combustion chambers.

If there is a need for increase of 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 start opening 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. Thus both valves open on full height and with the maximum duration, providing increase of 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 blocking of VTEC

PERFORMANCE ORDER

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 from above on a casing of an oil filter (behind on the right wall of the power unit) and is best of all looked through through an arch of the right forward wheel.

2. Disunite the socket of an electrical wiring of the electromagnetic VTEC valve. Measure resistance between the plug of the socket and weight. The nominal rate makes 14 ÷ 30 Ohm, 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 existence of 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 demanded value makes about 12 V, otherwise it is necessary to check a wire on a site between the socket and RSM for existence of breaks or short circuit on weight.
5. Switch off ignition and make sure available conductivity between the plug of a brown-black wire of the socket of the sensor switch of pressure of oil and weight if conductivity is absent, check a brown-black wire for break on a site between the socket and a point of grounding.

6. Remove 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. Remove a casing of a transitional nozzle of an oil filter from the engine block. Check passability of the filtering element and a condition of sealing laying.

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

Yokes

PERFORMANCE ORDER

1. Bring the piston of the first cylinder into the provision 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 heads of cylinders (see the Section Removal and installation of covers of heads 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 (see an accompanying illustration). 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 VMT).

Proofreaders of valvate gaps

PERFORMANCE ORDER

1. Assemblies of four proofreaders are put in special pockets in each of heads of cylinders of the engine. Assemblies of yokes have to be removed for the purpose of ensuring access to proofreaders (see the Section Removal, check of a state and installation of assembly of yokes).

2. 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. Dismantle assemblies on components.

Components of the synchronizing assemblies of VTEC:

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 she did not burst and did not give. 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. Manually check freedom of movement of pistons. Replace defective details.

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, and only after it establish on an axis (see the Section Removal, check of a state and installation of assembly of yokes).