vsv question
 

What are the two vsv's located under the intake manifold for? I broke one (the one towards the front of the motor) and it costs 75 from Toyota, and i was trying to figure if I really need it.

Fuel pressure up and EGR vacuum control... and yes, you need them.

Well, I dont have egr any more, and why exactly does the fpr need a vsv? does it cut down fuel pressure at idle or something?

Never mind, read about it. Is it still needed with an adjustable fuel pressure regulator? And if it is, what would happen if you removed it?

VSV (Vacuum Servo Valve)
 

Hello
The (energized) power up VSV allows atmospheric pressure to the fuel pressure regulator at start up and for one minute after to give a higher fuel pressure than the vacuum regulated pressure. Helps to start faster idle smoother. Removing it or having one that is defective means that fuel pressure will always be regulated by manifold vacuum or pressure. This can be a problem for a heat soaked starting engine. A rough idle at start up due to vapor lock can result.

The (energized) EGR VSV also blocks off the vacuum and allows atmospheric pressure to the vacuum modulator of the EGR keeping it closed until the engine reaches operating temperatrue. Removing it or having one that is defective means that manifold vacuum will be applied to the vacuum modulator when the engine is cold. It can result in rough cold acceleration / running. Note that vacuum is not applied to the vacuum modulator at idle. The throttle has to crack open for it to operate. Otherwise the engine would stall.

Here is a helpful link about Toyota's EFI system including the 7MGTE engine.

http://www.autoshop101.com/forms/h22.pdf

nice link!

here's much more on that site too. Here's the link to the technical pages section: http://www.autoshop101.com/autoshop15.html

Supra VSV
 

Thanks for the homepage link.

After reading the article (and not being sleepy) The main purpose of the EGR VSV is to keep the EGR valve closed until the engine has warmed up by blocking the vacuum. Even a defective VSV has some functionality. The default (unenergized) state of a VSV is to allow vacuum to pass through. The result would be a little more nitrous oxide pollution until the engine has warmed up. JDM Supras don't have a EGR system at all. A defective Fuel pressure up VSV would allow vacuum to the regulator at start up and as usual.
Driveability would not be greatly impacted by a malfunction of either VSV provided the hoses are connected.

JDM Supras also use different timing and fuel maps which take the higher combustion chamber temps into account. ;)

ok im sorry to ask, but what is a JDM supra? something from japan? Im really in the dark about this. Ill research it tomorrow but if someone knows before then. Fill me in please.