Well, this is an issue that has been discussed a lot and people offer different solutions:

using the Toyota filter,
changing oil regularly,
grounding the solenoid control wire,
rebuilding/replacing the assembly.

But after having read through many faqs, I am yet to find a simple shcematic diagram that shows exactly how the thing works. Can someone please explain this to me (and others who are wondering) ? It will definitely help me make a decision on which solution to choose.

thanks !
Ninjarider

 

This link doesn't show you how it works, but it does show what it does or suppost to do http://www.v6performance.net/forums/...highlight=VTEC Its written by our very own board member SteVTEC

 

Seems like the cam phasing improves low rpm power and cam changing improves high rpm power. I was aware of the way the two technologies work, but I wasn't aware of their effects, which brings me to ask:

1. why does cam changing improve high end power and cam phasing low end power ?

2. honda's site does a brilliant job of explaining EXACTLY how the compoents work in their VTEC cam changing system, but i'm yet to see any schematic of the components which facilitate Maxima's cam phasing NVCS system. I know there's a solenoid which allows oil through, but that's about it. The TSB from Nissan wasn't too helpful although it did have a cross-section of the solenoid assembly. I'm sure someone here can explain this with the help of a diagram. Please help ! I'm sure the diagram will help a LOT of folks.

thanks,
Ninjarider.

 

Its just a mechanical timing advance for the first half of the rpm range. They turn off during the second half of the rpm range for the natural torque peak to kick in. Simple as that.

The problem lies in turning them off, thats the job of the huge spring thats in the assembly, the spring goes bad with age and needs to be replaced with a beefier one in the rebuild kit.

 

Read the TSB in the FAQ's on rebuilding the VTC and there is a diagram of the operation. There is a split helical gear that engages the body of the VTC, and the rotation is translated to the intake cam. The return spring in the body brings the assembly back to its starting position. So there is only timming advance during the low rpm range, the FSM will give the exact conditions as to when they are on and off.

 

I read that cam advance is OFF during idle, ON just above idle revs, then OFF again past about 4000 rpm.

I have vtc tick so I grounded mine, so does this put the advance permanently ON or OFF ??

 

According to Matts current dyno, he lost power at higher rpms with them grounded. That would lead me to believe that they are on perm. BUT why does that keep them from ticking?

Also, according to the link above, during light loads on acceleration below VTC switchover point, the VTC sprockets aren't advanced (on).

Disclaimer: Im no expert on VTC's, I'm just now starting to find out how they function.

 

"I have vtc tick so I grounded mine, so does this put the advance permanently ON or OFF ??"
-ON, advanced, thats why a lot of people say their idle is real rough afte grounding them.



"BUT why does that keep them from ticking?"
-When they are grounded and turned on, the spring is fully compressed, hence no tick.


"Also, according to the link above, during light loads on acceleration below VTC switchover point, the VTC sprockets aren't advanced (on)."
-Correct, its in the FSM, only under very light loads the vtc's stay off.