my tvis doesnt work...

[daywalker]

i think my tvis does'nt work because my low revs and tork is gone i cant feel any power below 4000 rev. it was working yesterday but it does'nt now.so do you have any advice for me to check, any vacuum leak or electric problem.does tvis works with electric or is it just a base system?is there any part that usally brokes down or something like that? thnx

[ZDoman]

there is a VSV (Vacuum Switch Valve) on the tvis plate. it used to die. when you remove it you can check if it works, if you suck one side and put 12V on, it must open.

And nowadays 2 of my friends has problem with tvis ground (the ECU breaks the ground, not the positive!) By this time we didn't find the solution of this problem.

daywalker Wrote:i think my tvis does'nt work because my low revs and tork is gone i cant feel any power below 4000 rev. it was working yesterday but it does'nt now.so do you have any advice for me to check, any vacuum leak or electric problem.does tvis works with electric or is it just a base system?is there any part that usally brokes down or something like that? thnx

[oldeskewltoy]

The VSV is the round vacuum assembly between the runners... it is often called a "dashpot"(it looks like 2 pie plates put together). The vacuum goes into this and pulls a diaphram that activates the TVIS.

[alex-evo]

hmmm.... on mine the blue connector isnt connected
wht does it do ?

[banpei]

The blue connector should give the ecu signal to the vsv to close the valve and thus close the butterflies.
From what I understood the butterflies remains open when no signal is on the vsv or when there is no vacuum connection.

[alex-evo]

hmmmmmm.... i need to connect this for tvis to work and wht is the main advantages of tvis i know it increases low end tourque abit also will it help with fuel. I have HKS cams and the blue connector was disconnected when i got the car so is it worth reconnecting tvis as i heard that it chokes the airflow at a lower RPM when parts of the engine is upgraded. Also there is no power/tourque below 5000rpm even a granny car is quicker .

sorry for hijacking the thread

[banpei]

The tvis shouldn't matter that much in torque on a stock engine (few percent), it's mainly there for cleaner exhaust gasses. I don't know what the influence would be on non-stock cams...

I think that mainly depends on what how the cams are setup because that influences the character of the engine more. You could always try to connect it again and see if that helps...

[Ivan141]

Sounds like my daihatsu when the vacuum leads to the distributor where loose. But the 4age doesnt have vacuum advance so that cant be it. I'd look around for vacuum leaks though.

[oldeskewltoy]

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.........

[totta Crolla]

TVIS killed the bottom end power on my cammed '86,
noticably better without it. Stock engine is noticably better with it :wink: