Lets talk AVCS, boys.

So I got my built motor in today. I got the AVCS heads, so I need to figure out what to do with them to make them work. My personal issue with it, is that I do not run stock ECU and cannot run AVCS compatible ECU. I am runnign TEC III.

However, before I go into that, I want to figure out how AVCS works and how it does it.

Please provide as much info as possible.

 

Have you seen this? Courtesy of jon in[CT]

http://jon.in.ct.home.att.net/2004AVCS.pdf

 

I haven't looked at the AVCS on EJ20 but I have a wiring diagram of EJ25 AVCS motor.

AVCS has Solenoid and AVCS Camshaft Angle Sensor on each head.
The AVCS camshaft angle sensor is not replacing the usual camshaft angle sensor and the regular sensor is still there.

Total of 4 wires are going into ECU from AVCS mechanism.
(2 solenoids and 2 sensor.... 1 wire each goes to ECU)

AVCS is basically adjustable sprokets activated by solenoid so that the angle of the camshaft can be adjusted while the vehicle is running.
Same system as Toyota's VVTi or Nissan's NVCS

 

Well, yes, there is a sensor and a selenoid on each head. However, I do not think that the sensor actually does anything important.

Just like on the TGV's, the sensors simply tell the ECU that everything is "ok" and the advancing and retarding is happening according to the ECU instructions. It simply compares the crank and the main cam angle sensor outputs adds applied timing correction and reports to the ECU that the system is wokring. In case the mechanism is broken, the sensor will trigger a CE light telling ECU that something is wrong. What I am trying to say, that the sensors do not tell ECU what to do. They simply overlook the stuff. Thats my opinion based on the research I have done so far.

So, the main question is, what kind of signal does ECU send to the AVCS mechanism to do what it wants it to do? 0-12v? I pulled out a selenoid, which actually looks more like a variable valve and it has a number of oil passages that are opened and closed allowing various timing alterations.

Lets keep it going...

 

New developments...

I am putting my motor together at the moment and the AVCS valve/selenoid gets in the way of the front injector connectors. The injectors have to be rotated 180' to make it work, then the connectors have to be connected prior to bolting the fuel rail down. I am using VISHNU rails. I had to machine them a tad to make the connectors clear the rail itself.

I will post pics later.

Come on, people, lets talk this dealio.

Also,

I spoke to someone who just dynoed suby with a swapped JDM EJ20 w/ AVCS. AVCS was not connected and the car made gobs of top end power.

This means that if we were to leave the AVCS disconnected, the timing will not be at 0'.

I guess to have it dynamically advance and retard might be too much to ask. I am thinking to find a voltage that will advance/retard the timing just enough to have an overall gain and leave it at that.

 

seems like Nissan NVCS system is on-off thing and it is controlled by rpm. If AVCS is the same system, you can have TEC3 give the signal to AVCS at a certain rpm you choose and make it work.

Another option is.. eliminate the AVCS. If you just leave it with no wire, i think it's gonna stick with low rpm valve timing.
Replace the sprocket and adjust it right. Throw HKS cam shaft in too, hehe.

I'm still seraching for more info.
I hope AVCS is on-off thing.

 

in that case, i think it's easier to use traditional adjustable sproket.