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I supported Toymods
Location:
Perth, WA
Registered:
May 2003
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4age bigport TVIS
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Sun, 05 October 2003 11:45
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The guy who owned my car before me said he had blocked off a vacuum port to get a little more power from the car. is this true? he used a piece of eletrical tape to cover up the hole. i took it off and my car started idling at 2.5k(normally its around 1k) what should i do?
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Location:
NSW, East Coast
Registered:
July 2003
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Re: 4age bigport TVIS
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Sun, 05 October 2003 12:48
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He probably had to adjust the idle when he blocked it. Depends what it is where talking about.
Take off the tape, try adjusting the idle, from memory it should be about half way in turning the idle adjuster.
Hope it helps
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: 4age bigport TVIS
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Sun, 05 October 2003 13:01
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It sounds like you should now plug that port up to the t-vis actuator to get it working. This will also bring the idle down.
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Location:
camden
Registered:
September 2003
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Re: 4age bigport TVIS
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Sun, 05 October 2003 15:24
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hey dude, yeah it sounds like something to do with the tvis system but is hard to understand as you havent explained where abouts it is but i hope you fix it dude...
umm and a question,how would a 4age bigport responds to no tvis? 
cheers guys
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I supported Toymods
Location:
Perth, WA
Registered:
May 2003
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Re: 4age bigport TVIS
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Sun, 05 October 2003 15:32
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if i can find a pic of the inside of the throttle body i can show u. im still looking for one tho
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Location:
Adelaide
Registered:
November 2002
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Re: 4age bigport TVIS
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Mon, 06 October 2003 05:08
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There is a rubber hose going to the tvis plate vacuum actuator under the manifold. All you have to do is take the rubber hose off and block it with a screw or small bolt. It shouldnt change the idle of the car dramatically at all, but if it does adjust it. Dise3ngaging the tvis with give you smoother driveability and small power gain from the midrange to the top end of the rpm scale. I did this to my car and the idle was fine and found that I could take the car well towards 6500rpm without any hassles, but with tvis I couldnt do this as much as the engine felt strangled.
Good Luck! Regards, NOS4AG!
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Location:
camden
Registered:
September 2003
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Re: 4age bigport TVIS
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Mon, 06 October 2003 09:34
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I could take the car well towards 6500rpm
my mate use to have a ge in his corolla and his easily revved to 7800rpm and had more in it....so the tvis is more a acceleration thing?
cheers
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Location:
Bundaberg, Qld.
Registered:
May 2002
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Re: 4age bigport TVIS
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Mon, 06 October 2003 12:32
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 taken from the Club4ag tech pages..
TVIS - Keep it or Remove it?
There have been many, arguments on the issue of TVIS on early model 16 valve 4A-GE. The TVIS creates higher velocity intake charge at the engine's lower operating range by closing off one intake runner of the pair on each cylinder. Now, this is a highly effective method of making usable torque curves while retaining higher volume flow at high operating range. In most near normal applications, generally meaning light bolt-on tuning, the TVIS continues to function very well. Thus keeping it is a very good idea. However, heavier modifications including ECU, Carburetion, highly aggressive valve train/cam and internal work all present effects which create difficulty in controlling these items. For example, the triggers for the TVIS will be eliminated for carbureted applications, and it's variable induction, even if it was operational presents more complex challenge to jetting your carburetors. Heavily modified engine which greatly alters maximum rev range and shifts the power band in either direction will present similar challenges to an ECU programmer as well. In those cases it is easier to remove the TVIS and use the capabilities of the ECU tuning or carburetor jets to match your desired torque range. In short, for most basic performance upgrades, the TVIS should be kept and maintained to give nicer overall torque curve which does NOT inhibit power in any significant way.
all the mr2 folk in the states have had worse perfomance by removing or disconnecting their t-vis when still useing a 4age bigport.
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: 4age bigport TVIS
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Mon, 06 October 2003 15:44
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There is absolutely no doubt about it, once the intake manifold has been removed & the operation of the T-VIS system has been observed & understood, disconnecting the T-VIS will NOT give any performance increase. By disconnecting the t-vis, you are only affecting the operation of the system at low revs, where you should notice a lack in power. Once you hit 4 1/2 grand you'll notice an improvement in power because the t-vis is normally disconnected at this point and is effectively operation as it normally does. This may fool you into thinking you've made a power gain in the top end, but you've really just lost power down low. It would probably feel more linear too, as there is no sudden change in the induction system, whereas there's a noticeable change when t-vis is operating.
If anyone wants to know more about T-VIS, here's some of the results of a search:
http://forums.toymods.org.au/index.php?t=msg&g oto=169082&rid=37&S=8eb4448259b76c34553918 4f99557c33
http://forums.toymods.org.au/index.php?t=msg&g oto=157252&rid=37&S=8eb4448259b76c34553918 4f99557c33
http://forums.toymods.org.au/index.php?t=msg&g oto=98670&rid=37&S=8eb4448259b76c345539184 f99557c33
http://forums.toymods.org.au/index.php?t=msg&g oto=39198&rid=37&S=8eb4448259b76c345539184 f99557c33
T-VIS IS GOOD, DISCONNECTING IT IS BAD, DISCONNECTING CANNOT GIVE MORE POWER!!!!!!!!
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: 4age bigport TVIS
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Tue, 07 October 2003 00:01
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i love the search function! 
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I supported Toymods
Location:
Perth, WA
Registered:
May 2003
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Re: 4age bigport TVIS
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Tue, 07 October 2003 05:55
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guys i need a pic of the inside of the throttle body to show u's
im not even sure it is the tvis port.
cheers
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Location:
Terrigal
Registered:
May 2002
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Re: 4age bigport TVIS
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Tue, 07 October 2003 06:57
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I might be wrong, but I think you are talking about the idle up valve.
This connects to the underside of the throttle body.
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Location:
Terrigal
Registered:
May 2002
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Re: 4age bigport TVIS
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Tue, 07 October 2003 06:58
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I had to block mine up also. As the engine was originally FWD, but now RWD. The water pipes were all wrong and I ended up with no coolant going into the throttle body to warm up the idle up valve.
So I just blocked up the pipes for now. As it would take Forever to idle down to normal rpm.
A job added to the list of things to fix though 
Cheers
Joel
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I supported Toymods
Location:
Perth, WA
Registered:
May 2003
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Re: 4age bigport TVIS
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Tue, 07 October 2003 07:20
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could u take a pic of it to confirm?
thanks
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Registered:
October 2003
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Location:
Adelaide
Registered:
November 2002
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Re: 4age bigport TVIS
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Tue, 07 October 2003 13:13
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Oh, Did I mention I was running MTX8 aswell! 
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: 4age bigport TVIS
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Tue, 07 October 2003 14:28
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Unless the t-vis butterflies are removed completely, there is absolutely NO difference between having them disconnected & having it working above 4500rpm. Did you even click on any of those links I put up???
T-VIS only affects the intake at low revs, where it needs a restriction because the ports are so bloody big, & there's no computer in the world that will make a standard 4age run better without the T-VIS, not even a Microtech! 
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Location:
Adelaide
Registered:
November 2002
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Re: 4age bigport TVIS
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Sat, 11 October 2003 07:26
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I actually removed the tvis plate altogether and bolted the manifold straight up to the head and YES it did make a difference. Have you done my conversion BIGWORM? Id like to know because I compared dyno sheets after wards and had an extra 4kw at the wheels without the tvis plate altogether! No, I havent got photos of the dyno sheet, but why the hell would I lie, we are all helping each other here with our different opinion arnt we?
Regards, NOS4AG! 
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Location:
Brisbane
Registered:
February 2003
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Re: 4age bigport TVIS
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Sat, 11 October 2003 08:50
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sorry to hijack thread - but my 1G-GTE also has TVIS system.
i'm going to run a Megasquirt ECU which doesn't know what TVIS is - and i suspect there's some smarts in the factory ECU for determining when/to open the TVIS system - apart from the 4500 rpm enable point ... so
... do any 1G owners report similar power output observations with TVIS enabled/disabled/removed on 1G engines?
E.g. either less power under TVIS activation point (like BigWorm) or an increase overall (like nos4ag)? or never noticed?
tia, Charles.
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: 4age bigport TVIS
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Sat, 11 October 2003 10:43
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Dise3ngaging the tvis with give you smoother driveability and small power gain from the midrange to the top end of the rpm scale. I did this to my car..
I actually removed the tvis plate altogether and bolted the manifold straight up to the head and YES it did make a difference.
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Gee, there's a fair difference between disengaging the T-VIS & removing the plate altogether. And the manifold doesn't really bolt straight up, as the 2 end studs are too long without the t-vis.
I havn't done "your conversion", no, but I have removed the T-VIS plate & installed a phenolic spacer in place of it, but that's in preperation for my turbo conversion, not to try to gain more power while it's still relatively standard.
So you dyno'd your car before & again straight after performing only this modification? On the same dyno? And with exactly the same conditions in both instance? 4kW could easily come down to slightly different ambient temps & dyno error.
No, disinformation doesn't help, especially when people are here trying to learn about these things & take what they hear as the truth. Your first post is very misleading to what you're saying now. Next time be a bit (a lot) more specific when refering to technical topics, disengaging has a very different meaning to removing altogether.
Chuck, there really is no smarts deciding when to switch over t-vis, it simply happens at a set rpm (don't know if the 1G is the same as a 4A) and if the megasquirt has an aux output, simply set it to switch the vac switch at a given rpm.
T-VIS is really a rather complicated system to get working as well as it does, unless your motor has at least bigger cams or is turbo'd etc, it would go better with the t-vis active.
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Location:
Brisbane
Registered:
February 2003
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Re: 4age bigport TVIS
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Sat, 11 October 2003 13:34
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thanks joel,
am not sure of the heratige of my 1G (was transplanted from a luxo-barge into Helmanns yellow RA40 before i got it) - tho am reasonable sure it's always been Twinturbo.
i was wondering how the ECU drove the TVIS on a turbo engine - as you would really want the butterflys open once boost starts - but boost can happen a lot lower that 4500 - and you don't want to be chocking off the end of the runner while trying to spool up a turbo?
maybe there's some notes about it somewhere...
| BigWorm wrote on Sat, 11 October 2003 20:43 |
<big snip>
Chuck, there really is no smarts deciding when to switch over t-vis, it simply happens at a set rpm (don't know if the 1G is the same as a 4A) and if the megasquirt has an aux output, simply set it to switch the vac switch at a given rpm.
T-VIS is really a rather complicated system to get working as well as it does, unless your motor has at least bigger cams or is turbo'd etc, it would go better with the t-vis active.
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The MSquirt can drive aux outputs (if you write/modify the code and install a few more parts) - tho i would probably make enabling TVIS a combo of boost and/or 4500 rpm. There's a few people hove added bits to Msquirt to turn on water injectors, fans, NOS, 2nd inj's, etc...
Charles.
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: 4age bigport TVIS
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Sun, 12 October 2003 07:48
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It would be an interesting thing to experiment with on a turbo engine, and the fact that it's used from the factory on a 1G-GTE makes me wonder if it could be used on a turbo 4AGE effectively.
I imagine it would still be fairly similar to the 4AGE trigger, do the stock turbos take long to make boost? I would thing they would be on full standard boost fairly quickly, therefore boost might not come into the equation.
But even then, with an aftermarket turbo setup (say on a 4A-GE) that would most likely boost a little later than the stock turbos on a 1G, the T-VIS maybe could be useful to help against lag to a degree.
But then again, it's in a high/higher than stock application that T-VIS might and is said to do more bad than good when your at high revs & boost/airflow.
But have a play around with it if you can.
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