Celica Forums General Discussion Exterior Possible solution to VVTL-iVVT-i control...

Check out the following site. it has some nice diagrams on how the valvetrain in our engines work. My goal is to start a thread to brainstorm on how to control the variable timing and lift in our engines...

here's the URL to the page with the info:
http://www.billzilla.org/vvtvtec3.htm


There are two ways of attacking this problem:

a: go through the ECU, either by reprogramming it, or adding a piggyback controller of some sort to alter the ecu's signals.

b: go through the OCV (oil control valve) directly, and altering when it engages. This part is the equivalent of the VTEC's electronic solenoid. This would be an easier way to control it.

it should be noted that it is entirely possible to make an aftermarket OCV that works differently from stock, so it can get the desired results.

Any ideas or insights you have on this would be awesome. maybe if we put our heads together, we can make some horsepower!

sounds good man, let me know what you find out, not really my area, but anything that will help go a little faster! check out my post about the trd supercharger as well... might have a way to make it work for the gt

Found even more info... I snagged this from another site...
If you don't want to read all the docs, skip down to the 2nd set of "-----------------"

VVTi and Variable Lift:
-------------------------------------------
Toyota Celica's state-of-the-art 1.8 litre 2ZZ-GE engine has intelligent variable valve timing and intelligent variable lift (VVTL-i).
The variable valve timing and variable lift technology gives Celica a combination of driveability, fuel efficiency, low emissions and high performance.
Toyota's intelligent infinitely variable valve timing system is more advanced than the binary systems in some German luxury vehicles and Japanese small cars.
VVTi is a flow-down from the Lexus luxury car program and the Prius hybrid vehicle.
Celica has the latest-generation TMC-developed vane-type VVTi control, which is used on Prius, Lexus IS200 and Echo.
Intelligent variable valve timing will go into widespread use on Toyota vehicles.
VVTi provides continual variations of the intake valve timing, to provide ideal valve timing (and hence ideal engine characteristics) for the full range of driving conditions.
High Lift, Long Duration: Toyota's variable valve lift system operates on the inlet and exhaust valves. The Toyota 2ZZ-GE engine switches to the high-lift camshaft settings at 6000rpm. The high-lift cam lobes increase intake lift by 54 percent to 11.2 mm and exhaust lift by 38 percent to 10.0mm.
The high-lift cam profiles have the effect of increasing valve-opening duration, and therefore the range of inlet timing variation.
Valve overlap can vary between 4 degrees (full-retard inlet setting and low-speed lift settings) and 94 degrees (full advance inlet and high- speed lift settings).
A valve overlap of 94 degrees would normally be associated with full race engines.
For comparison, superseded Celica's 5S-FE engine had six degrees of valve overlap and the sports two-litre 3S-GE engine in the first front-drive Celica model had 14 degrees of overlap.
Inlet camshaft timing is varied according to engine revolutions, throttle position, inlet camshaft angle, engine coolant temperature and intake air volume.
Variable Timing Activation:
Toyota Celica's VVTi is a computer controlled and oil-pressure activated push-push type system, using the engine oil.
The engine ECU can command the system to advance or retard the inlet camshaft timing, thereby providing for faster response.
The hardware is a camshaft timing oil control valve (mounted adjacent to the inlet camshaft gear wheel) and a VVTi controller mechanism built onto the inlet camshaft timing gear.
The camshaft timing oil control valve is a spool valve, controlled via a coil and plunger by the engine ECU.
It can signal advance, hold or retard.
The VVTi controller consists of a housing on the front of the timing wheel, driven from the timing chain, and a four-bladed vane coupled with the intake camshaft.
When the engine ECU requires a change in inlet timing, it signals the oil control valve to provide oil pressure to either the advance or retard side of the four vane chambers.
Inlet cam timing is set to the maximum retard position for engine start-up, operation at low engine temperature, idle and engine shut-down.
A locking pin in the controller locks the camshaft timing in the maximum retard position for engine start-up and immediately after start-up (until oil pressure is established) to prevent any knocking noise.
Celica's VVTi system can vary inlet camshaft timing over a range of 43 degrees relative to crankshaft angle.
However, the variable lift system has the effect of increasing valve opening duration, so the full range of inlet timing variation is 68 degrees.
(Taken from the maximum retard intake valve opening in the low-medium engine speed range at minus 10 degrees BTDC to the maximum advance intake valve opening in high engine speed range at 58 degrees BTDC.)


Variable Lift Activation:

Toyota's intelligent variable valve lift system uses a cam change-over mechanism to increase the lift of the intake and exhaust valves when engine revolutions exceed 6000rpm.
The hydraulically activated variable-lift mechanism is electronically controlled by the engine ECU and shares some of its hydraulic control hardware with the VVTi system.
It has the same system inputs as the VVTi system - crankshaft angle and revolutions, air flow, throttle position, inlet camshaft angle and engine coolant temperature.
The variable-lift system will not operate until coolant temperature reaches 60 degrees.
The mechanism includes camshafts with two sets of cam profiles, for low-to-medium engine speed and high engine speed (high lift).
The full system includes eight rocker arms (one for each pair of valves), two rocker shafts (located inboard of the camshafts) and a spool-type oil control valve on the aft end of the inlet camshaft.
The rocker arms are the heart of system.
They have an integrated needle roller cam follower, a rocker arm pad and hydraulic rocker arm pin.
In normal operation, the low-to-medium speed cam acts on the needle-roller cam follower and the rocker arm operates its pair of valves.
Meantime, the rocker arm pad rides against the high-lift cam lobes, but moves freely within the rocker arm.
In this state, the rocker pad does not contribute to rocker arm movement and therefore makes no contribution to valve activation.
When the engine is operating in the low-to-medium speed ranges, the oil control valve is open to the drain side.
However, when engine revolutions exceed 6000rpm, the oil control valve closes the drain side and hydraulic pressure flows through the rocker shafts to the hydraulic rocker arm pin.
The hydraulic pressure pushes the rocker arm pin out to lock the bottom of the rocker arm pad.
With the rocker pad locked in its full extended position, the high-lift (high-speed) cam lobes now operate the rocker arm and hence its pair of valves.
When engine revolutions drop below 6000rpm, the oil control valve opens on the drain side, to relieve pressure on the cam changeover mechanism and allow the system to return to normal lift conditions.
Celica's 2ZZ-GE engine has shim-type valve clearance adjusters and narrow valve stems to optimise gas flow.
------------------------------------

Okay, to control VVTL-i and vvt-i, we must tap into the OCV valve, and manually engage it.

It works through the sensors, but appears like it can manually be controlled, just like a VTEC solenoid.

In theory, you could bypass the ecu altogether, and hook up a physical controller to the OCV, which is a spring and plunger-type valve controlled by the ECU (which means it's electronic, duh!)

In theory, you could wire a shiftlight in series with the OCV solenoid, and merely install a pill (To determine the RPM level for engagement), and when the shift light comes on, the 2nd profile on the cam will engage, and on VVTL-I motors, the lift should engage as well (I think it's done all on one solenoid, just like VVT-i, it seems the mechanism just adds lift at the time the aggressive cam profile pops in.)

It looks possible, and it will work on both the 1ZZ and 2ZZ engines. This may be the VTEC killer.

More as this develops. please keep posting feedback.

a celica beast, a hybrid monster sent to banish all hondas into the depths of hell. i love it!! but whos celica is gonna be the guiny pig?

Well, I'm gonna need to investigate a bit more. I don't know the voltage of the OCV solenoid, and I've got to figure out ecactly how to make this work and dial it in.

It's also possible that an ordinary vtec controller may do the job, it's just a matter of figuring the voltage, and making existing hardware work with it.

I figured this out lokking at VTEC swaps into pre-vtec hondas, they mentioned that they had to make a manual VTEC controller, and I figured, well, the ECU must control the VVT systems somehow. I researched a bit, and now, I may be on to something. As soon as I can learn a bit more, i can begin to prototype a controller. You could also put it on a switch, to manually engage it, but that is kind of risky.

It's possible, it'll just take a little time.

Looks good so far. Let's keep this going. any insights welcome

pushing a button manually while shifting and trying to keep the car strait seems like it would be very hard. the only way i could see that working is if there was a button on the shifter knob, but it would still be hard to do and time it perfectly. it really should be done automaticly by the ecu. what if you put a GTS ecu in the gt with the vvtl-i head?

in theory it sounds good.

there is already a way to control lift.

Buy an apexi power FC for the celica its only sold in japan and would have to be minorly retuned for 91 octaine gas, but you can control where lift kicks in

the XS engineering turbo kit uses this power FC and tuned lift to kick in at 5800 rpms on the dyno, not on the tach, so on your tack it will feel more like 5600 rpms, instead of the 6K on our tachs and 6200 rpms on the dynos!

I think there is more than just the OCV to engage lift.

Toysport already tried to make one of these a while back in 2001 and had no success!

not to bring you down, but Hey if you can do it more power to you!

The A'pexi Power fc does not use the existing OBD-II system on our cars so it doesnt not conform to SMOG standards.

well, in essence, you are correct when you say it takes more than the OCV to control lift, the ECU takes readings from various sensors. Inlet camshaft timing is varied according to engine revolutions, throttle position, inlet camshaft angle, engine coolant temperature and intake air volume. The info is drawn from the sensors, and the ECU has different maps, depending on different conditions in the engine (example: Lift will not engage, and the motor won't rev past 6000 unless the engine is warmed up. ECT, or engine coolant temperature sensor, determines this.)

The ECU takes all this into account before engaging the OCV to switch cam profiles and engage lift. This is how the car does it from the factory.

Also, it seems that the system is no longer just a simple on/off setup (was like that on later 4AG engines) rater, it works on a variable pressure system to change the amount of valve overlap, retard and advance, so it's a lot more flexible.

From my research so far, I found that the OCV is responsible for controlling the changeover, probably different voltages sent from the ECU specify how much the valve is flowing or draining. This is a good thing, because it will allow for more accurate tuning of the engine.

However, when you rip away all the BS, the OCV is the link in the chain that determines which cam profile the motor uses, and wether or not lift is engaged.

Something similar to an Apexi S-VAFC would be wonderful, as it allows you to tune the motor in 500 RPM steps. The goal is to seize manual control of the valve, so you can dial it in the way you want, rather than have the ecu make those changes based off factory settings.

The existing products are flexible, but are also expensive, and need to be tuned by the vendor, often times, they are not flexible enough, and rely on pre-made maps that can't be changed much. Once installed, you can't disable them, unless you swap in your original ECU.

The goal is simply this:

find out just HOW the OCV operates, what voltages open the valve to various levels, and emulating that with external hardware. the device, when completed, will allow for the factory ECU to control everything, or allow an optimized map to control the OCV when switched on.

Since sensors come into play, a device which alters the sensor maps, like the SAFC may do this just fine, but it only allows for a +/- 50% alteration in the signal, the difference required for the desired effects may demand 100% high cam under 50% retard, or something messed up like that.

Don't just think, read the info I posted. Take a look at how it works, when all is said and done, the only part we need to focus on is the OCV, as it is responsible for the oil pressure changes that switch cam profiles and adjusts the timing and lift.

Everybody wants to attack it at the ECU, but as many have said, it's code is difficult to crack, since it's encrypted.

I'm talking about making a stand alone controller, that works in conjunction with the ECU.
It will need to be tuned on a dyno, just like any vtec controller.

Lastly, this wouldn't do much unless you have some performance mods on your car to optimize in the first place.

Okay, time for an update...

Some time next month, my friend & fellow tuner Yoey will be assisting me in developing an OCV controller. Yoey is a UTI grad, and an expert deisel mechanic. This may not sound like much, but at his day job, he services Garbage trucks, so not only is he a hell of a mechanic, but he's a wiz with electrical and hydraulic systems.

I talked to him about my plan today, and he's knowledgeable of OCV valves, not only are they used in the hydraulics of the trucks he works on, but some of the deisels he works with use a similar system for timing adjustment.

We will be probing an OCV from the 2ZZ with his multimeter, and look through some service manuals to figure out exactly how it does it's thing. from there, it's a simple matter of assembling the required bits to control it independantly. once we get to that stage, an actual controller shouldn't be far behind.

However, as payment for his assistance, I will be contracted for some slave labor, helping him turbo his 2003 Cavalier, which shouldn't be as hard, but will take more time than the OCV controller

Aside from that, on a side note, I just completed some installs on my GTS, an Axas Combat power shift indicator, and a two-socket receptacle for accesories. The receptacle is hidden behind the fuse panel, and all the wiring for the shift indicator and my radar detector has been routed to it, all hidden nicely under the trim for a clean install. I did this to keep the lighter plugs intact for future use on other cars, as well as to have spare sockets when I need them. the receptacle can be removed from it's hidey-hole and placed in the cabin when needed. Best of all, my factory lighter socket has nothing plugged into it anymore, so it can be used as a lighter again. The shift light is all dialed in and works great! as for the control box, it's been mounted verticaly in the left-hand side of the glovebox. all in all, it took me about 1 1/2 hours to do everything (this includes a trip to buy some posilock connectors). the actual LED bar is mounted just above and to the left of the tach.

I'll hopefully post full details and pics of the install soon. Either way, it's worth the work for a little extra convenience and peace of mind.

wait...you can control VVT-i...whats there to control?

because it would be cool since i have a gt an all

That's the goal, actually, both VVT-i and VVTL-i.

VVTL-i is first, since that's what I have to work with. It's all done through the Oil Control Valve, which is a solenoid that regulates oil pressure to the cylinder head's cam switching mechanisms. How it's controled; I'm still working on it, but just the same, I should have some more answers in a month or so. I'm in the development stage right now, I don't even have a prototype controler yet. but as soon as I have something that works, I'll be sure to post the info.

Right now, I'm just trying to manually control the valve, I will still have to make a programmable controler, and dyno tune it.

As I said, you need some mods on your car to see any gains; the system is already optimized for stock celicas. It WILL need to be dyno tuned, and the gains, well, I'm not sure how big they'll be, probably similar to tuned VTEC on the VVTL-I.

I started this thread so people with info on the OCV or any related systems could post it here to help me out, and to keep everyone informed of project status. So, don't get too excited just yet. But with any luck, I should have some useful info in the future.

I still believe it is possible. Looking into a piggyback controler to handle OCV control, but don't know how much custom work it'll require.

I also have another buddy who can design and build protptype circuits for me, so that's a plus (unless of course, it requires a programmed PIC controller, in which case, I'll need to rethink my strategy, as we have no working PIC programmer)

BTW, if anyone has a SAFC installed, and has noticed a difference in how their lift engages after dialing it in, either post here about it, or send me a PM. Anything you can tell me will help me out a lot.

From what i have read, the S-AFC helps, but the ecu re-adjusts back to stock after a week or so, and people have only been seeing any increas in lift at wide open throttle. i have access to and the knowledge to program something called a basic stamp... they run about $50-$100 a piece and are desinged to provide low voltage singnal outputs from 16-48 pins (depending on model) they are produced by a company called parallax (http://www.parallax.com). they are fairly easy to use, and are reprogamable. if you are talking about reding senors inputs, and sending activation signals to the OVC, this could deffinately work. it is desinged for robots with multiple sensors and controls, this application should be a piece of cake.

i hope you guys figure this out, this could be a major breakthrough!

yea you guys figure it out and i'll eat some more ice cream

hmmmm interesting man!

yeh all you gotta do is get a fully reprogrammable ecu and there you go, you can control it wid the hand controller providing you got one wid it... it's already been done, there wouldn't be no break through i would already have a vvtli controler if i had the $2000 laying around...

in lift all the time...

MPG = 5

I'm also gonna try the shift light as a control(5,000 pill).
I have hardware for my laptop to connect to the obd2 connector. I will be able to read the fuel mixture when the vvtl is activated at 5,000 rpm. I will also update you guys as soon as I find some time to do this. I have all the necessary hardware, but do not have the time.

Cool... I thought this thread was gonna die.

Thanks to those who have offered your knowledge on this thing, homebrew experimentation is cool as well.

Stamp programming may do it, I've messed with it a bit; Pete's worked with them before as well, they are fun and you can make some interesting projects with them, but I'm not sure if a basic stamp will do the job, Code must run fast, and may be too complex, it'll take up lots of space (storing fuel maps on stamps may be too much unless you employ multiple stamps... Still worth considering) I'm looking into assembly as the programming langauge and using flashROM instead; a LOT more flexible. but stamps may work too. I'll run it past pete and see if he can get some ideas.

I also love the idea one guy had to make an ITB manifold for the GTS. It would make this mod much more effective.

A stand-alone controller is different from a complete ECU replacement. it's cheaper, and only controls the OCV solenoid, bypassing the ECU.

100% lift isn't a good option, maybe like 4500, 5000 RPM engagement, only for at the track, too, 5500 is good RPM for street.

Individual throttle body setup would make the lift engagement noticable at lower revs, much like the stock setting is noticable. the bottleneck is our TB/intake manifold combo. Early lift engagement will only be effective with an ITB setup, and would not be 50-state legal. However, with some extra work on internals (cams, etc) lift controller would be benificial as well.

All motor is still an option. OCV engagement is one of the hurdles we're trying to overcome.

I'm looking into toyota service manuals right now. Will post more when I have something substantial.

Keep experimenting guys, and keep me posted.

Any updates on this in the past 15 years (yeah I know I'm late on this but it intrigues me to know how to change when vvti comes in)