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VVTi - A discussion


Guest Terry S
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solenoid ( courtesy of Mig)
Feck me! That threw me for a second. Five ports - ;)

 

Its a four way valve with two drains. Deffo an infinitetly adjustable system, then.

 

Nice one, Mig!

 

*EDIT* You can also see that its a spool valve with an actuating solenoid and a return spring, so it will be a PWM controller.

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Sorta advanced and ahead of its time ...Varaible valve timing is actualy quite an old tech ..circa 30 years now ...just the limiting factors why it was not used on anything but high end stuff was mainly cost. Now that the cost of manufacture and emissions are so stringent it has come to the forefront and being developed more.

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Wow, that picture makes sense of things now, I think!

 

The middle bit either screws in (right) or out (left), right? So when it's at the right, the left hand top port drains oil out via the left hand bottom port, while the bottom central oil feed port feeds oil into the top right port, pressurising that side of the system. And when the middle bit is at the left hand side, it's the other way around.

 

But I see that if the middle bit can sit anywhere from left to right, you can balance the pressure of the system the two top ports feed by bleeding off less than 100% and correspondingly pressurising the other side less than 100%, so the adjustment ends up being less than 100%... Hence it being infinitely adjustable depending on how far the helical screw is turned. Genius.

 

I know what I mean anyway. Digsy? :D

 

-Ian

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Guest Usmann A

Ian,

whilst I am too thinking out aloud.You are correct in saying that ign timing is in crank degrees,duh :D ... the main reason for the cam sensor is the sequential fueling, so lke I said the EMS knows exactly what position the motor is at, so it can go about pulseing the injectors in the timing array of valve openings .. but it uses this for ign timing also, esp direct fire stuff, like we use, the EMS uses the no of pulses and then divides it by the no of cylinders to calculate engine speed, and then refrences that with the pulse from the cam sensor, to which it can then trigger the direct fire ign.

 

Say we run a Vvti supra with a 32 tooth trigger wheel.We would see 64 pulses every engine cycle(2 revolutions) so that means for every 10.6 pulses the Vvti EMS would fire two coils, thus the EMS would count the number of pulses off the crank and divide them by 10.6 to obtain exact engine speed.

 

It would then look at the pulse from the cam sensor telling it when to fire the inj, it would refrenfe the cam trigger comapred to crank no of pulses.

 

It would know the crank tooth at which the cam trigger would occur, normally 0 on the crank rotation and TDC on cly 1.

 

But having the 3 pulses I think are they to let the ems know what half of the cylce the motor is at, if so thats some sick shit right there, we talking bosch motorsport ecus that dont just depend on one pulse per cylinder, thats some EMS in that Vvti.

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Wow, that picture makes sense of things now, I think!

 

The middle bit either screws in (right) or out (left), right? So when it's at the right, the left hand top port drains oil out via the left hand bottom port, while the bottom central oil feed port feeds oil into the top right port, pressurising that side of the system. And when the middle bit is at the left hand side, it's the other way around.

 

But I see that if the middle bit can sit anywhere from left to right, you can balance the pressure of the system the two top ports feed by bleeding off less than 100% and correspondingly pressurising the other side less than 100%, so the adjustment ends up being less than 100%... Hence it being infinitely adjustable depending on how far the helical screw is turned. Genius.

 

I know what I mean anyway. Digsy?

 

-Ian

 

Sort of, but it doesn't look like a screw in/out thing. It looks like a solenoid valve to me. Each port is either fully on or fully off, rather than being a proportional flow control valve. The system is controlled by hunting the valve back and forth betwen ports.

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Sounds very wastegatey-style to me. Percentage opening via a duty cycle.

 

Judging by what Usmann has said as well it's all backing up the 4mb of data dedicated to the stock VVTi map :) Not just the control system data for positioning the variable inlet cam, and the closed loop control, but also the fuelling and ign timing correction maps based on what position the cam is currently at! Scary stuff :)

 

-Ian

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  • 4 months later...
Guest 99' spec rsp rz

Sorry for the thread revival guys, using the SEARCH function :) I've just come accross from the Aussie forums where I've spoken to Terry before and I've noticed more of you here have single turbo'd VVTi's...

 

I need to find and ECU that is going to run the car like it is stock - faultless starts, idleing, powercurve and well, you get it.. I wan the car to feel as if it came out of the factory with the single on it. I am the proud new owner of a T04Z if it makes any difference... all this I am reading about restarting the car and stalls and haveing to compression brake and running rich is scareing me wayy off wanting to single my car now.. has anyone found a solution?

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Guest 99' spec rsp rz

ok, its interesting to know AEM works, I was aware of the HKS F-Con from Terry's advice but the problem is that AEM has only been used on one car here so far and no one really knows how to tune it (this guy has had MAJOR problems) but luckily he lives in my city... I'll do some research into that, any other takers?? No one in Australia is able to tune an F-Con and flying smone from Canada is starting to really push the extravegant barriers...

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Guest 99' spec rsp rz

I got a crazy Idea... I am heading to Europe in two weeks and spending some time in UK as well while I'm there... is it possible to tune an F-con over there and bring it back here????

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I got a crazy Idea... I am heading to Europe in two weeks and spending some time in UK as well while I'm there... is it possible to tune an F-con over there and bring it back here????

 

Thats going to be one big suitcase if you can bring the car with you :nyah:

 

Pm Terry, Im sure he could think of something ..most if not all HKS pro dealer will not tune without your car on the rollers ..but give him a pm you never know .

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Guest 99' spec rsp rz

yep will definately have to look further into this, AEM looks like its got bad rep and from what I've seen here its siting right next to the F-Con for the number of people who can tune it. So HKS seems to be the only real option to get what I want out of this.. although Greddy E-Manage now looks to be an option?? anyone got any experience with this unit on VVTi??

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No one in Australia is able to tune an F-Con and flying smone from Canada is starting to really push the extravegant barriers...

 

Ship your car to Hong Kong, get single install and mapping all done here by the HKS pro dealer. Sounds crazy, but with the difference in price between here and there, it *may* actually work out cheaper in total.

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Guest Terry S
I'm running a 2jz-gte vvti and a 1jz-gte vvti with the AEM. It runs better than stock.

 

Would love to see you vvti unit portion of the map, can you post it? Be shocked if it did run better than stock.

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  • 1 year later...
Guest dori dori

Hi guys, my name is Grant and i own a 1997 VVTi 2JZ-GTE powered MZ20 Toyota Soarer in Australia.

 

In Australia getting decent VVTi info is hard so you can imagine my happines when i stumbled upon this forum.

 

I just want to ask advise on a few things namely power capability.

 

I am using an Australian ECU called Haltech E11 V2.

 

Haltech used my car to design and R&D their VVTi control on 2JZs and it runs very well. Alot of experts said Haltech couldn't run the variable VVTI control which made it all the more sweet to post up the dyno graphs etc.

 

Running a full factory JZA80 (non VVTi) turbo setup the car made 240kW at the wheels on 14psi. I don't know about you but this is on the low side here in Australia. Can is a manual.

 

This was on a Dyno Dynamics chassis dyno. We have since designed a twin turbo setup using the factory exhaust manifold with adaptor pipes to run twin KKR380 turbos. The turbos have 0.86 A/R turbine housings and 380hp compressor wheels and covers. Before we fixed a faulty cam angle sensor problem ran it made 260kW at 16psi. What i have noticed is that power falls away once the revs hit 6000rpm. Is this common on VVTi 2JZs?

 

I am putting it on the dyno next week and plan to push 25psi through the turbos and see what it does.

 

I am more than happy to post up dyno graphs etcs if anyone woudl like. Also what sort of power are you guys making with VVTi 2JZs? I am only one of three modified VVTi 2JZs in Australia and the other guys either don't want to discuss there findings or don't know jack.

 

Any advise you guys may have or dyno graphs i can compare to would be great

 

Cheers

Grant

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Guest VVTi
I am only one of three modified VVTi 2JZs in Australia and the other guys either don't want to discuss there findings or don't know jack.

 

 

What exactly are your 'facts' to support this? ;) Which three do you know of?

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Guest dori dori

Its personal experince asking various shops that have done work to VVTi 2JZs for advice. Advice they wouldn't or couldn't give.

 

I'll word it differently then, I am one of three VVTi 2JZ that i know of. Mine, a std VVTi 2JZ making similar power and another from a shop called Pro-Tek making 440kW plus. I have heard of another but its still in the built

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Guest VVTi

Fair enough.

 

Something that I find absolutely astonishing though is that the Protek Supra, has pushed over 30psi on a stock head and I saw the dyno graph the other day... he made peak power at about 9000rpms. Absolutely insane! I hear he might be heading down to the drags this weekend with a new tune pushing close to, if not 40psi. He's hoping to dip into the 10's. Anyhow, I found it very suprising when he told me himself that after several 30+psi pulls they pulled apart the head and everything looked neat still.

 

Also, I am now running a Garrett T04Z on an eManage Ultimate on a stock tune, awaiting the bedding in of my clutch. This is on a '98 TT 6 Speed.

 

Anyhow, Grant, if you don't mind me asking, does the Haltech actually control the VVTi or is it simply compatible with it? I remember back in my researching days I enquired about the Haltech's compatability with VVTi's but it was still being developed.

 

Also, have you possibly ventured onto http://www.supraforums.com.au ?

Let me tell you, there are MUCH more than just 3 VVTi supras running around. It must be an untapped resource for you! ;)

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