VTEC Operation
 

Accord 05V6 J30A-4
I am interested in the sequence of VTEC operations when the intake valves switch to high duration and lift.
Is oil pressure is applied through the Primary rocker arm and timing pistonto drive Synchronizing pistons A and B to lock the Primary and Secondary rocker arms to the Mid rocker arm?
Is the timing spring located in the Secondary rocker arm to drive the Synchronizing pistons back into normal position afteroil pressure release?
If not, what is the sequence?

RE: VTEC Operation
 

Hopefully this helps since I don't know the answer to that off the top of my head....


http://www.madabout-kitcars.com/kitcar/kb.php?aid=212

RE: VTEC Operation
 

http://auto.howstuffworks.com/question229.htm

RE: VTEC Operation
 

A little off topic but my Accord has a slight sputter at 2200 RPMs when accelerating. I assume its the VTEC as thats the approximate RPM range that it kicks in. Is it normal to have this little hesitation?

RE: VTEC Operation
 

I'm not very familiar with the 2007's but the v-tec on almost all honda's doesn't kick in until about 4,000-4,500 RPM's....

RE: VTEC Operation
 

The Q wasn't about output of VTEC.
Nor about when it activates.
Specifics of the sequence of events.

RE: VTEC Operation
 

I may not be talking about the right thing then. It it my understanding that on the new iVTEC engines, the engine runs on 3 valves per cylinder under 2200 RPM's and above that, it opens all 4.

RE: VTEC Operation
 

Here's my explanation based on available net information:

"A synchronizing piston connects/disconnects the three intake rocker arms. Hydraulic pressure against a timing piston moves the synchronizing piston A and B one direction, while a stopper piston and return spring moves the synchronizing piston back when hydraulic pressure is reduced."
Stopper piston is the same as Haynes description of Timing piston. The Timing Spring is behind theTiming piston.
Looking at the front cyl bank, the Primary intake valve and rocker arm is on the right side of the three rocker arms.
The Secondary intake valve and rocker arm is on the left side. It contains the Timing piston and Springto powerthe piston return to normal operation.
The Mid rocker arm is about one third again as large as either P or S.
In addition the system contains a Spool Valve and a Lost Motion Assembly.
The Spool Valve is an accumulator of oil pressure and volume for the hydraulic actuating sequence. Triggered by a solenoid likely timed off of the Camshaft Position Sensor.
The Lost Motion Assembly loads the Mid rocker arm toprecisely line up the three intake rocker arm bores.
Just before or during the beginning of the Compression stroke, intake valves closed, if PCM parameters are met for high output, the oil pump loads the Spool Valve, the Lost Motion Assy is activated and the Spool Valve solenoid is activated forcing oil through the Pivot Shaft into the Primary rocker arm driving the Synchronizing pins to lock P and S rocker arms to the Mid rocker arm.
Whendemand is normal, oil pressure is cut off, and the Timing piston is driven by the Timing Spring toreturn the Synchronising pistons to their normal position.
Must beprecise and reliable or rocker arms and pistons will contact.
I'm assuming the sequence is by cylinder.
It is also possible that the Secondary rocker arm is the oil pressure port to the sequence.
If anyone has seen the rocker arms disassembled, the Spring location would verify the rocker arm. Also the rocker assembly porting oil to the pistons would have a groove and the Pivot shaft holes to match.

RE: VTEC Operation
 

@MacLeod

I'll try to figure this out next time I take the car for a spin. Then again, I have AT so I dunno if that'll be much help to you. And I think the fourth valve kicks in around 2700-3000 RPM. When I floor it, it's normal accerlation up to around that range then the RPM meter goes off to around 5000+ RPM easy.

RE: VTEC Operation
 

duh

RE: VTEC Operation
 

The Q wasn't about RPM activation.

RE: VTEC Operation
 

The schematic of the valving was of some help.
If the Rocker arm assembly is rotated clockwise 120 degrees,it would represent the view over the front cyl headbank.
The drawing of the pressure sequence is crude and inaccurate.
Yellow shows oil flowing down the Pivot shaft and intoa rocker arm.
The rocker arms P & S are shown as a top (overhead) view looking down.
What appears to be holes in earsare valve adjustment screws.
Trust that wasn't out of a Honda manual.
Surprising that operational details of the system aren't widely known.

RE: VTEC Operation
 

I'll be sure to let Honda know you don't approve of their training modules from the interactive online university.
Sorry to bother you with the disagreeable information! I'll have to make a note of that in the future;
NOTE TO SELF; Post no info for RodgerB34 unlessI feel the need to be slammed and flamed.

There ya go all fixed now

RE: VTEC Operation
 

There aren't many car companies that release actual engineering information to the public. Including dealer service techs.

RE: VTEC Operation
 

Why would you want to reveal a secret to anyone in the first place anyways? ;)

RE: VTEC Operation
 

Had nothing to do with you
Take it anyway you like bro.

Honda doesn't reveal it's secrets?
LOL.
You don't think that GM/Ford/Chrysler and all competitors haven't reverse engineered their product?
Get real.

RE: VTEC Operation
 

Chery will be imported to the USA by Chrysler in a few years.
You can bet it will incorporate everyengineering technique feasiblefrom Toyota, Honda, VW, GM.
Some systems are patented.
Like Toyota split system hybrid in Ford Escape.
Others are not.
And those that are can be engineered around by a legal process that results in the same function different process.
Hence reverse engineering for the keys.

RE: VTEC Operation
 

I noted that theDIY VTEC drawing is correctly depicted.
For the rear bank.
It does showoil hydraulic pressureentering the Primary rocker arm, activating the Synchronization Piston A and B.
The Timing piston and Spring are in the Secondary rocker arm.
A remaining piece of the puzzle is the Power Shaft configuration.
Is it an open tube or segmented for each set of rocker arms?
My guess would be segmented for each set for independent timing.