Controlling VVTi

[thechuckster]

Weird, i thought it was a PWM solenoid wired up much like this:
(from here: http://www.oldschool.co.nz/phpbb/vie...746089#p746089 )


and from page EG170 in this (Tundra 2UZ service manual extract)
http://www.tundrasolutions.com/forum...o-5-7-4.7l.pdf
it has just one pin (OC1 & OC2) for each CAM positioner.

Can you throw up a link/scan/pic of the diagram in the manual you are using?

[JustenGT8]

I'll grab the page tonight but page EG-184 suggest how it is controlled and also came across this VVV which reflects the PWM signal the manual presents. So does appear i made this more complicated then it actually is


I was doing a bit of reading and came across a pdf of how the VVT-i works on a 3UZ, it will also be applicable to the later 1UZs. While it uses the oil pressure it works the same as most other variable valve setups and should be no problem for a high end aftermarket ECU that supports VVT as it is not affected by oil pressure variation or anything funky that is 1UZ/3UZ specific. The pdf explains it all but in a nutshell it works by using a two way oil valve that is PWM (pulse width modulated) controlled, ~50% duty cycle means that the cam timing stays where it is (referred to as hold mode), >50% duty cycle advances the cam timing and <50% duty cycle retards the cam timing. The ECU commands the cam timing to a certain point (most likely a 3D lookup table of load vs RPM would be used) and uses a magnetic reluctor (similar setup to the crank trigger, only this cam sensor has only 3 “teeth”) in the middle of the intake cam to determine when it is at the desired position. So from that it it would seem most likely that it is controlled using a PID (proportional integral derivative) control routine in the ECU, something similar to what is already used for other tasks inside the ECU such as idle control and closed loop fueling.

[nuk1ear]

3 PIN vvti? My guess, the 3rd pin is just the shield being grounded at the ECU

[thechuckster]

You could probably setup a discrete vvti controller based on what's available online. I would do something like

On the ECU, use an aux output to provide a PWM or logic signal based on either:
- 3D map (rpm versus MAP) altering the PWM duty cycle as noted in the map
- 2D map (rpm) and altering the PWM duty as noted in the map
- logic switch (user defined setting for changing aux signal from low to high)

With your custom controller you:
- need rpm/tacho input (to know when engine off, cranking or running)
- what is cranking & idle rpm (for startup)
- needs to know whether getting PWM or logic signal
- needs to know what frequency to run PWM output at
- needs to know what frequency to expect a PWM input signal at
- needs to know what cam position each trigger is at (so you can set the upper/lower bounds of the 2D map and identify home or zero position)
- 2D map to correlate input PWM to cam position
- min and max cam position (if using a simple logic input)
- midpoint starting position (you make this variable if starting at 50% is problematic)
- limp setting (if no ECU signal or position sensor fubar, the default to this)
- error tolerance (ECU and sensor input)

On startup, the controller does what the factory setup does:
- on power up, solenoid set to 50% (midpoint) PWM
- wait til engine above cranking
- after idle established, locate home cam position and alter midpoint position PWM to suit
- if cannot locate home position, revert to limp PWM and indicate error

On running:
- if error indicated, re-check for home position after error tolerance period expires (reset if error persists)
- get input PWM signal, determine cam position, alter PWM output, check each CAM position, repeat


Other considerations:
- if your ECU is using one of the cam position signals to provide a home signal, then you would have to pass thru that signal to the ECU. On the upside, you could use the controller to condition a VR signal to a simple logic signal.
- needs some reset/error tolerance in case the controller resets mid-running (input and power conditioning would be a feature here) and how to monitor if the output side gets damaged (e.g. monitor output signal and report error if FET driver gets borked or the solenoid goes open circuit).

[JustenGT8]

Yeah looked like a good idea for 30 seconds Chuckster For one cam there is probably an of the shelf controller out there to do it? For 2 cams? Beyond my CBF level though either way

[Celica RA45]

just turn them on and turn off. run both wires to both solinoids, as they are only inlet cams on a v8 they move the same way ,just play around with them on the dyno to see whats the best

[JustenGT8]

just turn them on and turn off. run both wires to both solinoids, as they are only inlet cams on a v8 they move the same way ,just play around with them on the dyno to see whats the best

Yup, that is now the plan.

Don't suppose anyone has any solenoide plug connectors or know of a source? I scored a set of plugs for the COP but no luck yet for these.

[JustenGT8]

Here is the female end of the plug i need. Does it look like any other plug i could scrouge up the male end by any chance?

[trdee]

have you had a look on the ballenger motorsports website? they do a metric fucktonne of different plugs...

[JustenGT8]

have you had a look on the ballenger motorsports website? they do a metric fucktonne of different plugs...

Nope, never heard of them so thanks for the tip

Have found solenoides with plugs on Yahoo, but $200 landed, so will look around before biting that bullet.

[dumbass]

looks like something on the harnesses i got at home
i bet u could cut down the tabs on the side of that sensor and fit an auto trans 2 pin speed sensor plug
or even some vsv solenoid plugs
if u come over u can go thru my 80lt box of plugs hehehe

[trdee]

come over? from act to qld?

[JustenGT8]

This is where i kick myself for throwing out old plugs and odds and ends of loom over the years

[dumbass]

well u cant keep everything
i throw out about 10 to 20 looms every year as i cant be bothered putting up with time wasters on ebay
so i throw em out
think ive thrown out 2 1jzgte looms and afew 2jzge looms
and some more
only one wirth keeping is the 20v one as they r getting harder to get

but cut the tabs off and most toyota ones will fit

[JustenGT8]

It does look like with the removal of the tabs, many 2 pin plugs will fit.....i'll have a scrounge in the shed as i still have bits and pieces lying around.