Almost all car manufactures, have got this system incorporated in their engines, under different nomenclatures.

Honda for instance, refers to its own as the VTEC system, while, Toyota (VVTi/), and Ford refers to theirs as VTC.

The nomenclatures are not a problem. They all perform the same functions, irrespective of vehicle manufactures.

Their major functions has always been improved fuel economy, and engine performance, by making use of the VTEC (or VVTi, or VTC), in adjusting the intake/exhaust valves of an engine.

HOW TO KNOW A FAULTY HONDA VTECH SYSTEM
1. Sudden loss of power during acceleration. The engine RPM won't go beyond 3000RPM, and above, because the VTEC system isn't kicking in.

2. Check engine light lits on the dashboard, with a P2646 trouble code retrieved.


WHAT CAN CAUSE THIS PROBLEM?
1. Low oil level, or dirty oil. Dead oils are embodiments of carbon deposits, and debris, from long duration of use.

2. Clogged VTEC system screens. For this Honda Accord, it has three strainers/screens of the VTEC system, where debris and dirt's easily clogs.

3. Using the wrong kind of engine oil viscosity recommended by Honda, or your manufacturer.
Some oils may not provide the necessary flow pressures(rates) needed by the VTEC system, in adjusting the timings.

4. Chamfered VTEC system wiring harnesses which maybe short-circuited,and/or unplugged connectors, which may lead to power problems to the VTEC switch.


HOW DO YOU FIX THE PROBLEM?
1. Check the level of the oil in the engine, and top up, if it's low.
Always replace engine oil and filter as at when due.
This would keep the valve train, and VTEC system super clean.

2. Visually check the VTEC system harnesses for short-circuit problems.
If the wires checked ok, the problem maybe coming from the VTEC system itself.

3. Time to take up some tools to work. Remove the VTEC components, and check for clogged screens.
Any trace of debris or dirt's on the screens, should be cleaned properly using carb cleaner, or replaced, since they are cheap

4. When replacing the screens, always apply little touch of sealant on the seals before mounting it.



CAUTION:
1. Do not reuse the VTEC components seals, if they already look brittle.
Reusing them would cause oil spills on the rear of the passenger side rear top cylinder.

2. Do not automatically replace a VTEC switch, just because your scanned result showed a rocker arm actuator fault.

3. At every cleaning of the VTEC system screens, always ensure you replace the engine oil and filter at the same time.

4. Always start with the simple things first, before replacing the VTEC switch itself. Things such as visually checking the VTEC wires before replacing the switch.

5. Do not agree to anyone telling you, it's an engine replacement scenario here.



Finally, here are some short videos I did on interpreting the life data of the VTEC system, while I was test driving the car.



https://www.youtube.com/watch?v=GG7M09RUqbA



https://www.youtube.com/watch?v=SnknVNFtl7g

Clogged VTEC system. Look at the screen clogged with debris and dirt's.

That's another one. This switch is located by the engine mount at the passenger side right.

VTEC system shown with their screens clogged.


https://www.youtube.com/watch?v=57KWhGydJFA

Very useful thread. Thank you TRYGO

TRYGO:
Almost all car manufactures, have got this system incorporated in their engines, under different nomenclatures.

Honda for instance, refers to its own as the VTEC system, while, Toyota (VVTi/), and Ford refers to theirs as VTC.

The nomenclatures are not a problem. They all perform the same functions, irrespective of vehicle manufactures.

Their major functions has always been improved fuel economy, and engine performance, by making use of the VTEC (or VVTi, or VTC), in adjusting the intake/exhaust valves of an engine.

HOW TO KNOW A FAULTY HONDA VTECH SYSTEM
1. Sudden loss of power during acceleration. The engine RPM won't go beyond 3000RPM, and above, because the VTEC system isn't kicking in.

2. Check engine light lits on the dashboard, with a P2646 trouble code retrieved.


WHAT CAN CAUSE THIS PROBLEM?
1. Low oil level, or dirty oil. Dead oils are embodiments of carbon deposits, and debris, from long duration of use.

2. Clogged VTEC system screens. For this Honda Accord, it has three strainers/screens of the VTEC system, where debris and dirt's easily clogs.

3. Using the wrong kind of engine oil viscosity recommended by Honda, or your manufacturer.
Some oils may not provide the necessary flow pressures(rates) needed by the VTEC system, in adjusting the timings.

4. Chamfered VTEC system wiring harnesses which maybe short-circuited,and/or unplugged connectors, which may lead to power problems to the VTEC switch.


HOW DO YOU FIX THE PROBLEM?
1. Check the level of the oil in the engine, and top up, if it's low.
Always replace engine oil and filter as at when due.
This would keep the valve train, and VTEC system super clean.

2. Visually check the VTEC system harnesses for short-circuit problems.
If the wires checked ok, the problem maybe coming from the VTEC system itself.

3. Time to take up some tools to work. Remove the VTEC components, and check for clogged screens.
Any trace of debris or dirt's on the screens, should be cleaned properly using carb cleaner, or replaced, since they are cheap

4. When replacing the screens, always apply little touch of sealant on the seals before mounting it.



CAUTION:
1. Do not reuse the VTEC components seals, if they already look brittle.
Reusing them would cause oil spills on the rear of the passenger side rear top cylinder.

2. Do not automatically replace a VTEC switch, just because your scanned result showed a rocker arm actuator fault.

3. At every cleaning of the VTEC system screens, always ensure you replace the engine oil and filter at the same time.

4. Always start with the simple things first, before replacing the VTEC switch itself. Things such as visually checking the VTEC wires before replacing the switch.

5. Do not agree to anyone telling you, it's an engine replacement scenario here.



Finally, here are some short videos I did on interpreting the life data of the VTEC system, while I was test driving the car.



https://www.youtube.com/watch?v=GG7M09RUqbA



https://www.youtube.com/watch?v=SnknVNFtl7g

Hello boss. I'm currently having this issue right now, my technician want too change the rocker arm pressure after scanning. But u said not too change the rocker arm pressure just bcus it shows on the computer.. I wish I know a good technician that good handle or service the vtec for me in Ado-Ekiti