Can anyone explain how this works?

I'm guessing that the valves open either more or less and possibly the duration varies too with engine RPM?

How is this accomplished?

 

well, the CVVTS I guess is what you meant, Continuous Variable Valve Timing System... and I would assume it works alot like V-tec in a Honda, there is a primary and secondary lobe on the cams one is for low RPM idle/torque and the other is for high RPM power. To be honest, I don't even know at what RPM it switches over on our cars, I really haven't bothered to look into that :\

TCS is traction control system, which on our car is called VDC or Vehicle Dynamic Control which cuts engine power when rear tires spin and applies breaking power to wheels that are losing grip (like with cornering). I usually leave this off, unless it is raining.

our "Viscious" LSD, or Limited Slip Differential, makes you spin both tires and not just 1 for better traction/grip. It releases so you can make turns without the inner tire "skipping" and the outer tire spinning. Ever made a tight turn going really slow in a 4WD truck?

 

Thanks.

It is the variable valve timing that I'm curious about. I guess that would be C V V T S. 350Zforum.com had it listed on their specification page incorrectly.

If there are two cam lobes (per valve), how does one take over from the other?

re: tight turn in a 4x4...yes, I know what you mean.

 

pretty sure it is CVVTS, or VVTCS, hell I forgot :P You were probably right on the name, CVTC (Continuous Variable Timing Control)... point is:

"It causes a vane, housed within the cam drive sprocket, to rotate to advance or retard the intake cam shaft timing to maximize the engine's efficiency and power output based on engine and driving-condition information it gets from the engine control monitor. Advancing the timing improves low to mid range torque, while retarding the timing improves higher RPM performance."

So, it doesn't change lift or duration, only the timing. On a Honda V-tec, it changes lift and duration using 2 lobes, the 2nd which activates at a certain RPM. Our doesn't use 2 lobs, it's all computer controlled with timing advancing or retarding.

 

I've read the service manual and didn't see anything about it ???

 

Nissan just controls timing with it's CVTC system:

Some cars use a device that can advance the valve timing. This does not keep the valves open longer; instead, it opens them later and closes them later. This is done by rotating the camshaft ahead a few degrees. If the intake valves normally open at 10 degrees before top dead center (TDC) and close at 190 degrees after TDC, the total duration is 200 degrees. The opening and closing times can be shifted using a mechanism that rotates the cam ahead a little as it spins. So the valve might open at 10 degrees after TDC and close at 210 degrees after TDC. Closing the valve 20 degrees later is good, but it would be better to be able to increase the duration that the intake valve is open.

Source: HowStuffWorks.com

 

from what i understand, only the cam timing on the intake is variable. all CVVTS does is either retard or advance the intake cam, depending on a few variables, such as engine speed, RPM, throttle position, etc. nismo has a product that will allow the timing to be adjusted even more, but the confusing thing is the product description says up to 55 degrees. i don't know what that all is about, sayin' as to how you only need a couple of degrees.

but don't confuse this with vtec. there aren't two sets of lobes on these cams. so there really is no switch over point for us, it's continuously adjusting (hence the "C"). hope that helps, and if i'm way off, please educate me.

n1cK!

 

I don't know but VTEC is mad tight yo. I wear my tennis visor upside down sideways and throw my automatic Accord in neutral and rev it when I pass by the hotties.

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

 

n1cK!

 

Thanks to all for replying........but I'm still wondering HOW is it done??

If the camshaft rotation is advanced or retarded.... mechanically or electronically...how?

From what I have read in the technical manual, the crankshaft drives a timing chain, which drives the camshafts. I do not see any opportunity for the engine to adjust camshaft advance.

 

See the section on " " (quotes) that is from a Nissan Technical manual, not sure exactly which one I got the info over the phone from my brother... quoted word for word. The computer tells this "vane, housed within the cam drive sprocket, to rotate..." this rotation is what advances/retards intake cam shaft timing. Notice, like perviously stated, it only says INTAKE cam shaft, so apparantly it doesn't change exhaust cam timing.

Computer or Mechanical? Well, apparantly a computer controlled, mechanical adjustment

 

Based on what you have found, I looked in my service manual and found this. Interestingly, nothing in the service manual explains or shows how it works. I could not find any mention of CVTCS or any mention of variable valve timing. I am curious about how the "Intake Valve Timing Control Solenoid Valve" is able to affect a "vane" in a sprocket...........must know how things work

 

I've heard oil pressure is used to do the advancing, but I can't confirm that. Also, I believe the engine in the aniversary edition 350z has timing control on both intake and exhaust.

--
Jeff

 

You're not looking in the correct place in your FSM. Look in the EC section under the DTC P0011/P0021 IVT Control.

 

Beautiful. Thanks for your help IceY2K1Max

I was wondering how Nissan was able to create such a strong V6.

The ingenuity in this design is simply amazing.

It looks like you were right xephiron when you said it is both Computer and Mechanical.

Thanks for your replies.

 

my check engine light came on after i had another motor installed {hydrlocked the old one} Had it check out and was told it might be the cam timing and that my engine is running to rich. should i be concerned and how would i have this fixed?

 

Actually, the new 300 hp engines in the Track and 35th models have it on both the intake and exhaust camshafts.

 

have you taken it to the dealer? if so, what did they say they would do? if not, if your car is not heavily modified, try to get some warranty work done. they may have to reflash the ecu, check your sensors, and retime the engine (if the cam timing is off).

n1cK!

 

this maybe a dumb question but if you change you cams out and sprokets does this mean your engine no longer uses this feature

if so what happens if your computer tell your engine to adjust but it can't.