Toyotas TVIS - for the techy guys....

Hi all,

Just thought I'd pose a quick Q to anyone with in-depth knowledge of the T-VIS system.

I know its supposed to open at 4200RPM on the '91 3SGTE according to my BGB and about five million google search results. However....i linked an LED up to the pin on the ECU to monitor it and mine opens at

2000rpm. On the dot. Whether running 99 RON or 95 RON. After a reset ECU its the same.

Also, fuel cut is supposed to kick in at around 12psi, and always did with the old CT26 turbocharger. Having swapped to a CT20b (from the '95 engine) i now hit fuel cut at 15psi.

Can anyone enlighten me?

J
Reply to
Coyoteboy
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Time to join TN as a member and ask the Celica and MR2 guys. :)

Reply to
REN69

My 85 Hachiroku did the same thing.

Doesn't seem to be a problem. I was 'opening 'er up' to 'fkush the system' and the TVIS didn't seem to close afterwards.

The only things I have noticed since this happened was that the throttle response off the line was quicker (Yeee Haaa) and the gas mileage dipped by about 10%.

I drove it for 2 years like this before I parked it.

Reply to
Vash the Stampede

Theoretically it should drop the off-the-line torque a bit if the ports are open. Gas milage has always been cack, i dont even worry about that anymore so long as it doesnt change :D

It just confuses me as my ECU doesnt behave AT ALL like the stock one should, yet (although I've not opened it yet) it doesnt seem to have any modifications to it.

Reply to
Coyoteboy

Maybe it starts to open at 2000rpm, a variable type thing, so your LED is going to light anyway. Whats it like actually driving it, Can you feel it give a surge of power around the 4000rpm range? This could also be where the ECU kicks in with a more aggressive Fuel map to co-incide with the fully open TVIS butterfly.

As for the fuel cut at 15psi, isn't the CT20b more pressure less volume compared to the CT26, more volume less pressure. Depends how the air is measured on the GTE, probably an AFM. Just some idea's i'm not stating any of this as fact. But i have had abit of experience with all the generations of 3s gte's and ge's including the beams 3sge which is a very sweet motor. (220HP out of 2.0lt non turbo)

Reply to
cd

It has been a long time (probably over 15 years) since I studied the T-VIS system but I'll give it a shot.

T-VIS does stand for Toyota Variable Induction System ;-)

I believe that the TVIS is wide open at 4200 RPM but it does start to open sooner. The theory behind the system is to balance air velocity and volume so at low RPM, the T-VIS closes and the air enters through the primary runners at a high speed to improve combustion. At higher RPM, the secondary runners begin to open to add move volume. 2000 RPM sounds like the correct RPM to begin opening.

Whats it like actually driving it, Can you

It's been even longer since I studied the controls for the turbo, all I could offer is speculation.

Reply to
Ray O

I'm thinking you might be right on the 'starts' opening idea - though as far as i know its just a vacuum switch so doesnt partially open ?

As for the CT20b/CT26 (CT20b is actually just a modified CT26 IIRC, there was a CT20 which was is a tiny fast spooler for diesels i think) Id have said the 20b produced more volume and more pressure - it runs higher pressure as standard on the 3rd gen 3sgte, runs cooler charge at the same pressure (according to rough intake temp measurements), and also doesnt run out of steam and start dropping off pressure past 5K revs like the 26 - it holds to the red line no questions asked. My old

26 used to run out of puff around 5K, dropping from 12psi to 10ish as redline approached, the 20b holds 15psi happily right through. And seems to spool earlier to full stock boost (11.8psi) at 2700rpm, 15psi by 3000. Made my week when i fitted it lol.
Reply to
Coyoteboy

Toyotas TVIS - for the techy guys.... Group: alt.autos.toyota Date: Thu, Sep 22, 2005, 4:04am (EDT-3) From: snipped-for-privacy@hotmail.com (Coyoteboy) Hi all, Just thought I'd pose a quick Q to anyone with in-depth knowledge of the T-VIS system. I know its supposed to open at 4200RPM on the '91 3SGTE according to my BGB and about five million google search results. However....i linked an LED up to the pin on the ECU to monitor it and mine opens at 2000rpm. On the dot. Whether running 99 RON or 95 RON. After a reset ECU its the same. Also, fuel cut is supposed to kick in at around 12psi, and always did with the old CT26 turbocharger. Having swapped to a CT20b (from the '95 engine) i now hit fuel cut at 15psi. Can anyone enlighten me? J

--------------------

I need an acryonym to english translater to figure out what you are saying. Maybe that newsreader thingy that Phillip is talkin' about would help me..?

Ok..

LED - Light emitting diode... 0>) ECU- Electronic control unit?? PSI- Pounds per square inch Q- question... RPM- Revolutions per minute RON- I have not idea T-VIS- ditto BGB- again , no idea

Reply to
Charles Pisano

:) Correct up til RON = Rated Octane Number (like regular or premium unleaded are respectively 95 or 98+RON in english terms) T-VIS =- Toyota Variable Induction System - uses 8 runners in the intake manifold and shuts 4 of them off at low revs to maintain high gas velocity and thus better mixing and torque at low revs. At higher revs these open to allow the full manifold flow rate. BGB = Big Green Book - the toyota technical manuals for your car, used to be green, they are huge and contain just about every test and specification you could want.

J
Reply to
Coyoteboy

Oh, yeah...these things take off at 4400 RPM. You can definitely feel a kick in the seat of the pants when the system comes on fully. Almost turbo-like, but not as 'violent'(?)

Reply to
Hachiroku

:( I dont get the 4200rpm kick :( I get a goddamn enormous kick as the turbo comes on around 25-27, at 3K its nice then it seems to flatten off, not particularly badly but just seems to not follow through with what it promised at 3K.

J
Reply to
Coyoteboy

Oh. Mine's not a turbo, just a straight 16V T-VIS

Reply to
Hachiroku

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