View Full Version : VVTi - A discussion
An overview:
This thread was created by Terry Saunders to nail down the major differences between the VVTi and non-VVTi incarnations of the 2JZ-GTE. It expanded into quite a large discussion over the way VVTi works on the Supra, ending with a revelation that, once again, Toyota were well ahead of the game because it's an infinitely variable system - about 10 years before anyone else hit the mainstream with such a setup :thumbs:
-Ian C
Thought this may be useful. Please feel free to add to it:
PRO's
ECU. The VVTi has 2 x 16 bit whilst the stock JDM is 2 x 8 bit. The ecu is obviously much faster. It is based upon the later Lexus units and is very powerful.
Fly-By-Wire. In conjunction with the ECU the FBY system will close the throttle if it senses detonation, high coolant temps, etc
The VVTi system. Adjusts the intake cam timing. This gives significantly more low end torque, and helps the larger turbo'd car spool earlier.
Rev Limit. The rev limit on a stock VVTi is 7200 rpm whilst the Stock JDM is 6800 rpm.
Neutral
MAF. The VVTi uses MAF, The MAF is far more accurate than a speed density system. The downside is that the MAF will eventually become a restriction if big power is required.
Inlet. The VVTi uses a smaller inlet manifold. This will improve torque, but may become a retriction on really big power cars ( 650+ bhp)
Cons
Wasted Spark ignition. This IMO is a step backwards to coil on plug.
Trac. The VVTi TRAC is too over-sensitive. Pulling the fuse will put the car into "snow" mode.
Engine Mounts. This applies to all Facelift cars. TMC changed the engine mounts for some strange reason. These are prone to failure and are not as "beefy" as those on earlier cars.
Thanks for this bit of info...
Could come in VERY handy for something I'm working on.
Cheers dude...
Never a problem. We don't just sell things ;)
Thought this may be useful. Please feel free to add to it:
Rev Limit. The rev limit on a stock VVTi is 7200 rpm whilst the Stock JDM is 6800 rpm.
Thats interesting.
It's a bit of an assumption, but it suggests that the stock rev limit could be raised to the same level by pluggin in VVTi bits.
How do the stock cam profiles compare, VVTi to non? Do you know whether Toyota changed the valve spring and tappet stack height for the VVTi? Are the cam base circles the same? Any idea if the valvetrain was lightened in the VVTi? (Long shot, I know).
If the stack height and profiles are similar, then maybe VVTi springs could run in a non-VVTi to make te valvetrain safe up to 7200.
Thanks, interesting read Terry, can you explain why the MAF becomes a restriction on higher powered cars please?
Nic - it's huge, it takes up about 30%-40% of the cross-sectional area of the inlet tract.
Maybe they limited the rpms on the non-vvti because of the mild cams? It loses power above about 6000rpm anyway. The VVTi would make use of the higher revs (as would my cams :eyebrows: )
The VVTi ECU is VERY good at adjusting the fuel mix to hit stoich, way better than the non-VVTi ECU. Annoying if you are airflow mapping them :rolleyes: :D
No Idle Speed Control Valve either, it's all done off the FBY throttle, so that's one less thing to get gummed up and cause probs.
-Ian
Darren, never had cause to plug the head apart. I am sure we ill and will answer when I know, unless another performance tuner has already done it?
Nic, the MAF can only pass so much air. Some in the US were trying twin MAF mods to over come this. The US/UK MAF seems to top out around 500ish BHP. I have no idea on the VVTi as I have changed mine to a speed density system.
BTW Chis, found out yesterday that the 2 x TPS sensor bounce their readings off each other
I switched to the other TPS line and the light throttle opening resolution has improved massively :thumbs: That plus cleaning the coal and dinosaur corpses out of the throttle body/plate has really moved us forward with Alex's car :D
-Ian
I switched to the other TPS line and the light throttle opening resolution has improved massively :thumbs: That plus cleaning the coal and dinosaur corpses out of the throttle body/plate has really moved us forward with Alex's car :D
-Ian
The two TPSesses have different rising rates versus throttle opening, dont' they?
I swear Alex e-mailed me all this info when he first had his throttle problem. He's making you work it all out again from first principles. :D
Oh no, I knew it had two outputs, I just had to pick one to plumb into the E-Manage. I went for the one with the longest range, but it wasn't as good as the other one.
Besides, would I trust anything Alex told me? :sly:
-Ian
Just an updtae, we found the following over the weekend:
1/. The VVTi uses a different exhaust cam too, which we assume is an NA one
2/. The VVTi has a different piston skirt design, assumed weight saving to go with the higher RPM
Terry, As the VVTi engine design is circa 10 years old now, I'm guessing that it is a simple one-shot advance retard system, with only two running positions (as opposed to the state of the art systems than can run at any valve timing in bewteen two limits). Back then I think that the BMW VANOS system was the only one that was capable of varying the timing in this way.
Can you confirm?
Terry, As the VVTi engine design is circa 10 years old now, I'm guessing that it is a simple one-shot advance retard system, with only two running positions (as opposed to the state of the art systems than can run at any valve timing in bewteen two limits). Back then I think that the BMW VANOS system was the only one that was capable of varying the timing in this way.
Can you confirm?
Well there was a massive range of adjustment Darren, and if Reg Riemer is to be believed, the VVTi map in the ecu is huge and very complex. I wish we'd taken a picture of the gear now, but your probably looking a circa 4 degrees adjustment
Well there was a massive range of adjustment Darren, and if Reg Riemer is to be believed, the VVTi map in the ecu is huge and very complex. I wish we'd taken a picture of the gear now, but your probably looking a circa 4 degrees adjustment
4 or 40? Just checking that wasn't a typo. Up to 40 to 60 (crank) degrees swing is pretty common for cam-phasing units.
So all together you had a fun weekend?
Can I ask why you ended up doing this work to the engine? I thought you were going to keep the block as it was....
... I'm guessing that it is a simple one-shot advance retard system, with only two running positions ....
I remember reading that the VVTi can adjust the inlet cam anywhere within a 60 degree range, i.e. it's not ON/OFF
...just because we could Chris really, I had the rods already so thought it would keep us busy for a few hours ;)
The engine was literally as new inside, you could still see the cross hatching. There are no signs of any det, and the BCPR7ES plugs seem to be working an absolute treat.
...just because we could Chris really, I had the rods already so thought it would keep us busy for a few hours ;)
The engine was literally as new inside, you could still see the cross hatching. There are no signs of any det, and the BCPR7ES plugs seem to be working an absolute treat.
Good stuff. Think you might wana do another one?
:)
Sorry Darren, yes, and as John said it may be that much, but have nothing to back that up.
The valve springs look like normal TT ones BTW
Good stuff. Think you might wana do another one?
:)
Nope LOL.
Seriously though,depends on the spec and your wallet ;). Will never be done in a weekend again mind.....
:help:
Verrrrry sweet if it is an infinitely adjustable system. :thumbs: Good old Toyota :)
I can't post the whole thing because it's copyrighted material.
But this sums it up really:
http://www.max-boost.co.uk/stuff/VVTi.gif
sorry for the picture quality:(
The oil feed to the VVTi unit is via a banjo bolt on the side which incorporates a filter.
IIRC, the Vvti, has 3 pulses off the inlet cam, so its like the resolution is greater in the map, I know that the cam hall sensor triggers everytime cylinder no1 is at TDC. so it refrences it for ign and seq fueling, but the 3 pulses? Possible that wasted spark ign. triggers .., im unsure, possible for vvti? or just greater speed definition of the motor?
Any hoo, good stuff tel,that rebuild was quick ... :devil:
It's a bit of an assumption, but it suggests that the stock rev limit could be raised to the same level by pluggin in VVTi bits.
How do the stock cam profiles compare, VVTi to non? Do you know whether Toyota changed the valve spring and tappet stack height for the VVTi? Are the cam base circles the same? Any idea if the valvetrain was lightened in the VVTi? (Long shot, I know).
If the stack height and profiles are similar, then maybe VVTi springs could run in a non-VVTi to make te valvetrain safe up to 7200.
I have been told that the non VVTI engine can also rev to 7200, but without upgrading the cams you would gain nothing, the basemaps on the AEM have ignition cut at 7200 and then fuel cut at 7400.
With a built head people rev them too 8000 and higher, not so sure I would like to try that though.
:respekt:
Wasted Spark ignition. This IMO is a step backwards to coil on plug.
The coil on plug setup is awsome, do they run normal remote coils and ignition leads on the VVTI?
:thumbs:
I have been going to 7500 rpm.
I have been going to 7500 rpm.
In the VVTI or normal?
I can't post the whole thing because it's copyrighted material.
But this sums it up really:
http://www.max-boost.co.uk/stuff/VVTi.gif
Slight :hijack:
John, that document certainly is a good find. I have most of the non-VVT-i related documents on a CD but AFAIK "official" technical info on the VVT-i is pretty rare. Its even rarer to find someone posting up previously unsees documents on here these days.
If you can't post it all, can you tell us where you got that from? I'm still amazed than an engine of the VVT-i Supra's vintage has an infinitely variable cam phaser on it.
TBH, I think we need to start getting some VVTi info and just go public with it...
I've got things such as wiring diagrams for them.... and if others are willing to post info to help out the greater good then yes I would go public as well, but I have a real problem with people just sponging info and not sharing bits they have (not aimed at you john, because I've seen how much you have put on your site)
Gav
Soonto"HAS"soop
04-07-05, 22:24
Thanks for all of this Terry, one of the best new threads I've seen for a long time.
How the bloody hell is a technical description of the VVTi system copyright material?
Why not retype it and pass it off as your own? I'm sure that'd get around any potential accusations of copying stuff.
-Ian
Oh no, hang on, here we go:
http://autospeed.drive.com.au/cms/article.html?&A=1283
See the section headed "The Advantage of VVT-i " for where JohnA copied the text from :) Still don't understand the copyright issue going on there, hey ho.
Edit - shame they got the redline wrong, it's 7200rpm as Terry has found out, not 6800 which is the non-VVTi limit.
-Ian
Guess I should double check Terry's findings sometime...when I'm not driving Miss Daisy.. ;)
That article is great...I've got the best Turbo engine in the world :woot:
I've been a member of AutoSpeed from the beginning, and I've got all these articles in PDFs (they've now discontinued this practice and you can only access them online)
It is copyrighted, very clearly.
I also find it immoral to post their work, since the price of admission is so low. They deserve to have more people joining in, they're not a ripoff setup.
That's why I've got no Autospeed articles on my site, most other material I see as a 'free game' since it originated by the manufacturers, or from expired magazine articles.
It isn't exactly a technical article, more like a description, and as I said that extract contains the essense of that question.
shame they got the redline wrong, it's 7200rpm as Terry has found out, not 6800 which is the non-VVTi limit. I think the red line is 6800rpm, or thereabouts. The rev limiter is higher.
I think the red line is 6800rpm, or thereabouts. The rev limiter is higher.
Nice, next time Ian will be saying a Porsche is mid engined not rear engined...but that you knew what he meant ;) :lol:
I wonder if the 'members' area counts as public or not.
What do the mods think?
Maybe they could ask AutoSpeed if they agree for their 'Supra MKIV' PDFs (I've got five here) to be accessible to members here, in exchange for a banner or something.
Fair deal perhaps, and an ad for Knowling's book won't go amiss, it's pretty good actually.
What do you think?
I think the red line is 6800rpm, or thereabouts. The rev limiter is higher.
So Toyota didn't change the gauge face, sue me :p
-Ian
I wonder if the 'members' area counts as public or not.
What do the mods think?
Maybe they could ask AutoSpeed if they agree for their 'Supra MKIV' PDFs (I've got five here) to be accessible to members here, in exchange for a banner or something.
Fair deal perhaps, and an ad for Knowling's book won't go amiss, it's pretty good actually.
What do you think?
Sounds like a plan!
Could be made available in the downloads area.
It's a good idea I think.
Members here get more value, and AutoSpeed get some advertising, which is quite relevant as well (cheap, too).
Don't know if it's Branners or the mods who can chase this up, but it may not even take more than a few emails to sort out.
Straight swap perhaps.
In the VVTI or normal?
VVTi with the limit raised
Are you running a motec or something then?
:thumbs:
Yeah it has a V Pro ish in it
Not to diss Terry and Migs' photographic expertise, but does anyone have any good quality photographs of the VVT-i valve block and the end of the intake camshaft? I'd like to take a closer look at them.
sorry Darren they were taken with my phone
sorry Darren they were taken with my phone
I dunno half a bl00dy job!
I dunno half a bl00dy job!
LOL had other things on our minds rather than a photo build
:tongue:
Does the VVTI head fit on a non VVTI block, are the inlet and exhaust ports the same and how is the VVTI system controlled.
If we had more information on the control mechanism then new releases of the AEM software may be able to support it, AEM already support VVTI on other models.
:eyebrows:
Wez I believe Arnout is in the process of doing this.
Do you have a pic of the valve as well? I'd like to see how many ports it has.
only the one previously posted
Well, just to further the controversy, I'm wasn't 100% convinced that it is an infinitely variable system, but I'm as convinced as I can be, looking at the pics.
My scepticism lay in the age and the design of the system. Off the shelf infinitely variable systems are relatively new and all the recent ones have been vane-type - and the current VVTL-i system certainly employs the latter design to do the "VVT" part. The cam pulley on the VVT-i Supra is a helical spline design. You can see this simply by looking at the cam pulley itself. You can see the helical splines on the outside of the VVT unit body (see attached pic).
Toyota used at least two variations on the VVT-i theme: An early helical spline design and a later vane type. Also, according to this article (http://www.billzilla.org/vvtvtec.htm) they have also in the past used a simple one-shot, helical spline VVT mechanism on the 4AGE engine. Plus all the helical spline systems that I knew of (with the exception of BMW's VANOS) were one-shot types. Therefore I was all ready to conclude that the Supra mechanism was such a device.
The key is in the design of the camshaft nose.
One-shot devices use a single pressure feed and a drain path. Oil pressure is fed via a valve and ports (either in the head or a cam cap) into the camshaft. Sometimes the head is groooved and the camshaft is ported, or -as with the Supra- it is the other way around. When the oilway is pressurised the oil is fed through the cam nose into the VVT pulley onto one side of a piston, and the piston moves. The helical splines turn the axial movement into an angular movement between the pulley and the camshaft and this creates the timing adjustment. There is a constant leak path through the piston seals and this is returned to the cylinder head via a second pathway in the camshaft, which drains into an empty space in the cylinder head. When the oil pressure is removed, the piston returns to its rest position under spring pressure.
Variable devices have two pressure feeds (sometimes termed A and B on the control valve drawings): One feed acts on each side of the piston. The valve constantly switches between the two (using the cam position sensor for feedback) to keep the cam timing at the desired position.
Since the Supra VVT-i engine clearly hs two hydraulic feeds, which could be either "A" and "B" or "pressure" and "drain", we need some more details to fully confirm whether it is one-shot or fully variable.
The clincher would be the control valve. A one-shot system would be three-way, with an oil feed and a drain, either of which could be connected to the camshaft. A fully variable system requires a four-way valve with an oil feed, drain, and "A" and "B" ports. When "A" is connected to the oil feed "B" is connected to the drain, and vice-versa.
Without seeing inside the valve it is impossible to know for certain, but other details hint at a fully variable system too:
If the second port on the camshaft was a drain, there would be no need to route it back through the cam cap and into the valve body. It could simply break out of the camshaft behind the cam cap and drain into the cylinder head.
Lastly, fully variable systems always have oil flowing through either port A or port B - therefore the cam bearing always has an oil supply through leakage and does not need a dedicated oil feed for lubrication. A one-shot system shuts off the oil flow when it is not operating and so the cam bearing needs a second oil feed for lube. I think I can see these feeds on the near edge of the second and third cam bearings, but I cannot see a lube feed on the first.
A pic of the valve (or - lordy - the hydraulic circuit) would clinch it.
A pic of the valve (or - lordy - the hydraulic circuit) would clinch it.
If you think we are gonna strip the car down again............... LOL
Borrow Alex's for the weekend
:eyebrows:
:respekt: :notworthy
Isn't it nice when someone who knows what they are talking about shows up :woot:
-Ian
Still doesnt explain to me why they are 3 pulses off the cam hall sensor? :complain: :D
I know piddly all off Vvti supras, but thanks darren, that post just kinda confirmed what I thought how a helical Vvti system works .. and I learnt something new today.... :ecstatic:
Darren, if you can use my car to find out then you're welcome to.
Terry, will getting to the bit darren needs to see require any new gaskets etc? (My cam cover gaskets are crappy anyway)
Darren, if you can use my car to find out then you're welcome to.
Terry, will getting to the bit darren needs to see require any new gaskets etc? (My cam cover gaskets are crappy anyway)
Excellent:thumbs:
so this now begs the question, the VVTi cars running motec ecu's, have they spent the time to control the VVTi properly...
so this now begs the question, the VVTi cars running motec ecu's, have they spent the time to control the VVTi properly...
I take it this question is aimed at me as Im the only Supta VVTI running a Motec...
There was a French Motec specialist who setup the VVTI part of my Motec ECU. The whole process took 4 whole days 8-5 pm...to complete and for Motec Australia to accept.
Motec Australia rejected his first 2 efforts saying they knew it could be done better. I have not had ANY problems with the car since I had it back and it seems to tick over very nicely.
I am confident in the work because I saw the ammount of time and effort that was put in to it but thats as far as I can go. I have no idea of the quality of the work if Im honest.
No not solely at your car Chris as you werent the first Supra VVTi with an M800 in this country. I am sure the car works fine, it whether its working to an optimum that I am querying.
No not solely at your car Chris as you werent the first Supra VVTi with an M800 in this country. I am sure the car works fine, it whether its working to an optimum that I am querying.
I would not know... Is there any way to find out?
Also as far as Im aware My car is the ONLY VVTI single turbo supra running a Motec M800.. Motec confirmed this as it was the first VVTI map they had done.
only seeing the map. I assume you can access it?
How does the motec control the VVTI or does nobody know?
Does it work on just RPM or RPM vs LOAD etc?
How is the VVTI modulated, does it require frequency changes or simple voltage differences, i have no idea so would be interesting if someone has more info on this.
:thumbs:
only seeing the map. I assume you can access it?
I have no idea... This is when I will bow out gracefully.
If you think you can find out and want to see Im game.. :thanks:
guesstimate voltage Wez
So how do I know if I can access the MAP's and know if its running to the optimum?
You should be able to download the software from here :-
http://software.motec.com.au/release/
and then download the map from your car to your laptop/computer, if you have not done anything like this before might be worth taking extra care as you really do not want to trash your map.
:scare:
I would not know... Is there any way to find out?
Also as far as Im aware My car is the ONLY VVTI single turbo supra running a Motec M800.. Motec confirmed this as it was the first VVTI map they had done.
Whilst this (http://www.whifbitz.co.uk/mksmotor.htm) page says eManage I know it went MoTeC before you...however whether or not the VVTi is working as intended is another matter.
You should be able to download the software from here :-
http://software.motec.com.au/release/
and then download the map from your car to your laptop/computer, if you have not done anything like this before might be worth taking extra care as you really do not want to trash your map.
:scare:
Looks FUN but sounds dangerous!
How do I plug the lap top in ? :ecstatic:
Hmmmm, did they not leave you a link cable, hold on let me check if its a normal serial cable.
:thanku:
Interesting :-
Recommended Specifications:
PC running Windows 98/2000/XP
Pentium III or better
64Mb RAM or greater
Monitor with minimum of 800 x 600 resolution
Standard RS232 serial port (for M4/48/8 ECU & PLM)
Standard printer port (for ADL and M800)
USB port (for ADL2 / SDL)
You would need to get the link cable and i bet that isn`t cheap, do motec allow anyone to map there ECUs or only trained motec staff allowed?
If this is the case you may not even be able to get a cable :thumbdown
Also as far as Im aware My car is the ONLY VVTI single turbo supra running a Motec M800.. Motec confirmed this as it was the first VVTI map they had done.
No Mikes car had the M800 first and AFAIK it is still running the VVTi system ( so he believes). I have had numerous conversations with him over it. It had a emange in that he wasnt happy with and then went M800
Interesting :-
Recommended Specifications:
PC running Windows 98/2000/XP
Pentium III or better
64Mb RAM or greater
Monitor with minimum of 800 x 600 resolution
Standard RS232 serial port (for M4/48/8 ECU & PLM)
Standard printer port (for ADL and M800)
USB port (for ADL2 / SDL)
You would need to get the link cable and i bet that isn`t cheap, do motec allow anyone to map there ECUs or only trained motec staff allowed?
If this is the case you may not even be able to get a cable :thumbdown
Could well be just a boggo parallel cable...?
This is all fascinating stuff :) let's see the VVTi map /rubs hands with glee
-Ian
guesstimate voltage Wez
The vane-type systems use spool valves that are either on or off, so its a kindof pulse width modulation. One-shot helical systems also use on/off spool valves.
Older continuously variable helical splin systems? Not sure. We could measure the voltages on a suitable VVT-i Supra inthe Norwich area to be sure.
I assume the motec uses a PWM map for it?
I am wondering why this hasn`t been tried with an AEM yet as there is a spare PWM output and multiple spare normal switched outputs.
No good to me as I don`t have VVTI but just curious on how it all works, great info so far guys.
:respekt:
I assume the motec uses a PWM map for it?
If it is a PWM system, then it might - or it might hamstring it back to a one-shot system by switching the valve permanently open or closed after a specific speed/load point.
The vane-type systems use spool valves that are either on or off, so its a kindof pulse width modulation. One-shot helical systems also use on/off spool valves.
Older continuously variable helical splin systems? Not sure. We could measure the voltages on a suitable VVT-i Supra inthe Norwich area to be sure.
I'll tell Steve V to get in contact ;) :p
Just say when. ;)
If the AEM can do this stuff it would be great...but we need a AEM to VVTi loom converter :(
I think as Darren said it would restrict the VVTi system doing it with a PWM table. Motec made a big song and dance with the M800 and its variable came timing abilities, so it would be nice to find out what they have actually done, or whether it is a little "hype"
Darren how would you expect the stock VVTi EMS to control the cam timing assuming its not a one shot system?
Darren how would you expect the stock VVTi EMS to control the cam timing assuming its not a one shot system?
Via another map in the ECU for speed / load (open loop) stuff, and then there will be a closed loop feedback from the cam positon sensor. So the ECU is saying "for this speed and load you want this valve cam timing" (which equates to this pulse width), and then the feedback circuit is constantly comparing where the camshaft actually is compared to where it should be.
There are probably special cases for cold start, idle, limp home, etc.
Via another map in the ECU for speed / load (open loop) stuff, and then there will be a closed loop feedback from the cam positon sensor. So the ECU is saying "for this speed and load you want this valve cam timing" (which equates to this pulse width), and then the feedback circuit is constantly comparing where the camshaft actually is compared to where it should be.
There are probably special cases for cold start, idle, limp home, etc.
OK this is making sense, as Reg Reimer said he managed to view the VVTi map and that it was enormous, so much so that he said he wouldnt even contemplate messing with it, and that must have taken TMC engineers an age.
May also explain why the VVTi ECU is twice as powerful as the normal TT
Hands off my pics anyone thinking of robbing it :looney: http://www.billzilla.org/vvt1.gif
Hands off my pics anyone thinking of robbing it :looney: http://www.billzilla.org/vvt1.gif
OOOOO well done.
LOL. I've seen that pic on about 6 different websites today, and about the same number of cut and pastes of different people's descriptions of VTEC / VVT-i / VVL or whatever :)
we'll get there in the end tough.
Suprised there is not more input from others, little dissapointing.
The Motec can utilise any square, sine wave form or pattern and be configured using the correct alithograms for any sensor, it can read practically anything out there, but it needs the correction/software programme to be configured into the ECM to use it.
So if TRD had a motec guy spend a few days on it, then most probably it has been setup.
PWM is not much of a big deal at all, quite a few EMS can do this type of stuff, I mean hell we all have idle control valves .... LOL
We all know the cam sensor refrences to the EMS that cyl.1 is at TDC and the EMS fires ign,and fuel pulses from its built in timing patterns ..
But why does the VVti have 3 pulses, anymore care to measure at what degreee in crank rotation the pulses are triggering ..?
I think it is just 3 triggers for the wasted spark system ign .... but im unsure //?
You may be right U, the VVTi also utilises a 32 tooth trigger disk too
oooh, more resolution then ... but more resolution doesnt always mean a good thing,for aftermarket tuners anyway ... ;) LOL
tel, do you know what the fuel and ign tooth values are for the stock vvti .. ?
But why does the VVti have 3 pulses, anymore care to measure at what degreee in crank rotation the pulses are triggering ..?
I think it is just 3 triggers for the wasted spark system ign .... but im unsure //?
Just thinking aloud here but I don't think it'd be ignition related as a) ignition timing is worked out on crank position, b) it's variable depending on the load/speed map, and c) you'd need 6 triggers even if it's wasted spark, as there are still 6 spark events per 4-stroke cycle (well, 12 with wasted spark but it's 6 doubles IYSWIM)
No ideas to bounce back in return though... Could it simply be to keep a track on how advanced or retarded the cam is at any moment? For the VVTi closed loop feedback?! :blink:
-Ian
The increased number of teeth on the crank trigger disc might be for ODB stuff. The VVTi uses OBD, doesn't it?
The increased number of teeth on the crank trigger disc might be for ODB stuff. The VVTi uses OBD, doesn't it?
Yeah OBD2, the jap one
solenoid ( courtesy of Mig)
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.
I may be shy but I doo try :rtfm:
Superb work every one! :thumbs:
So what's the verdict exactly...advanced and ahead of its time? Or advanced but went down a technological route that's now been abandoned for a "better solution"?
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.
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
One (daft?) question - is it possible to retrofit a VVT-i head to a non-VVt-i block?
Yes, it wont run tho :tongue:
seriously you would have to change a lot of parts
Aw nuts. There goes that idea!
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.
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.
Actually - I'll check myself there. If you feed a solenoid (working against a spring) with a frequency, will it move part way? If so then it may work as a proportional flow valve.
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
99' spec rsp rz
01-12-05, 23:05
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?
I'm running a 2jz-gte vvti and a 1jz-gte vvti with the AEM. It runs better than stock.
The V-pro works really really well too.:yu:
99' spec rsp rz
01-12-05, 23:35
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...
99' spec rsp rz
01-12-05, 23:37
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????
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 .
99' spec rsp rz
02-12-05, 00:52
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??
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.
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.
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
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?
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
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 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! ;)
dori dori, I suggest you repost your question in the main Technical forum as these discussions are mainly for archive purposes. You'll get a great deal more input there.
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. He's hoping to dip into the 10's.
Anyhow, Grant, if you don't mind me asking, does the Haltech actually control the VVTi or is it simply compatible with it?
Also, have you possibly ventured onto 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! ;)
Cheers for that. is it possible to see the dyno graph? I was unaware the VVTi rev limit was 7200rpm! This is what i want to find out about. My motor leans over at 6000rpm yet Protek make power to 9000rpm? I was under the impression he was already running low 10s. To the best of my knowledge we are controlling the intake cam from idle up until 4500rpm. At low rpm is at feull advance and slowly retards as the revs rise. I will dig up a more detail answer later tonight.
Yes i have been on Supraforums but i don't get any feedback or advise there either. maybe its me?
Cheers
Hi - New to the forum but looking forward to it. I have a 95' Supra NA/t engine that I am building and would like to get rid of the distributor. Works fine, just gets in the way of the turbo. Am using a AEM EMS. Can I use the TT ignition system on this engine ? I saw a pic of a 98' NA that was a VVT-I. Can I do that mod to my 95' NA ? How about using the 7M-GTE ignition as the profile is much smaller. Any aftermarket ignition systems out there where I can shed the distributor ? Would appreciate any comments. dale
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