my tvis doesnt work...

[Ivan141]

If you take a look at the dyno plots toyota once provided, you'll notice TVIS only makes a few percent difference in torque.

[ZDoman]

I have a dyno with and without tvis on the same stock engine, its about 20nm minus at the bottom end without tvis.

I'll find the pic and share it here.

Ivan141 Wrote:If you take a look at the dyno plots toyota once provided, you'll notice TVIS only makes a few percent difference in torque.

[banpei]

oldeskewltoy Wrote:

banpei Wrote:The tvis shouldn't matter that much in torque on a stock engine (few percent), it's mainly there for cleaner exhaust gasses.

Please tell us where you found this information????


TVIS's purpose is solely to improve low end torque... at least that has always been my understanding of its purpose... to accelerate the incoming airs velocity(by closing half of the port down) so more air/fuel gets in the engine at low rpm.........

Here:
http://websworld.org/marcel/tech/tvis/tvis.html
As you can see in the torque curve in practice it is only a few percent. I do agree with you that in theory it should work much better. But probably the 4AGE does not breathe enough in stock form.

[ZDoman]

Sorry I remembered wrong, I have dyno plot from the without tvis condition only. but we felt a lot power gain at lower RPMs after repairing the tvis.

There are 2 dyno sheets, NOT from the same car, but both are 4age and ae86, they were dynoed at the same time on the same dyno. the second one's tvis didn't work...

[banpei]

Between those two there is a difference of 20nm, however what else was different between the engines? The second one also has a flat torque curve from 5000 rpm so there must have been another factor...

[max_ae86]

Today, I figure out that my tvis doesn't work. There is no vacuum in low rpm, and the butterflies are opened all the time. I disconnected the plug from VSV and check with voltmeter. One wire has 12,6V if connected with ground but the other wire is dead (no ground contact aether). Any suggestion? What should be on the other wire?

[max_ae86]

The other (dead) wire is connected directly to ECU. So there are two possibilities:
1) The wire has been interrupted somewhere
2) The ECU doesn’t provide ground

It seems I have the ECU problem. The wire to TVIS VSV is OK. ECU doesn't provide ground contact after ignition key has been turned on.

[max_ae86]

I found the resistor R515 has been fired up and totally dead (no continuity). I will try to replace it and check the TVIS pin again.

[banpei]

Auch. Good find.

[PatrickAE86]

good find

but there must be a reason why it's fired up.. ?