by Malcolm » Sun Aug 15, 2004 7:24 pm
t-vis uses a small vacuum plenum and a normally closed solenoid to control switching. The default position is for the butterflies to be open. When you turn your car on the ecu opens the solenoid, allowing the vacuum in the small vacuum plenum (which is fed by the intake manifold), to pull a diaphram which has an arm which is connected to the t-vis butterflies and opens them similarly to a throttle butterfly. So, there are a few possibilities. The solenoid could be unplugged or broken. There could be a leak in the lines, the vacuum plenum, or the diaphram. Or, as has been mentioned, they could just be so gunked up and the springs so stiff that they wont open. I would check that the solenoid is plugged in (it's behind the intake manifold), check that the lines are all connected, check the hoses etc for leaks, and then spray some CRC (maybe use a long thin tube to get it down the intake manifold), and if it still doesn't work then try taking the whole manifold off and investigating further.
Having said that the bluetop 4age isn't incredibly torquey at low revs anyway, so they might be working fine