TVIS

[totta Crolla]

I had a good look around the engine today and decided to do the TVIS test by removing the vacuum tube. There appeared to be no difference with it connected or not. There is a definate engine note change at 5000rpm with the pipe on or off.
After connecting a longer piece of vacuum tube to the valve and sucking on it I could hear something moving around in the inlet manifold, I'm sure it was the TVIS working.
If the TVIS was not working (stuck open) would I still get the engine note change and the extra pull at 5000rpm ?
Thanks

[The Doctor]

yeah, you would, but you DEFFO gonna notice a BIG drop in torque in the lower rpms!

[banpei]

Around the 5000 rpms the engine gets a lot more fuel, so of course it will change the engine note.

[Ivan141]

Not more fuel.. there is a kick in ignition advance around the point where TVIS kicks in to make it more of a boost.. The actual TVIS doesnt make a huge difference.

[totta Crolla]

The Doctor Wrote:yeah, you would, but you DEFFO gonna notice a BIG drop in torque in the lower rpms!

May be it is stuck open then as I cannot discern any difference with the pipe on or off, is there an easy way to close the TVIS and keep it closed to check for this ?

[banpei]

Ivan141 Wrote:Not more fuel.. there is a kick in ignition advance around the point where TVIS kicks in to make it more of a boost.. The actual TVIS doesnt make a huge difference.

I was refering to the speed-correction map in the ecu:
http://www.jmross.freeserve.co.uk/part2p1.html
Above 5000 rpm it starts correcting with adding a more rich fuel mixture.

But when I re-read the explaination I see what you mean: fuel mixture is only 8% correction, so the effect shouldn't be that big to give the kick...