03-28-2010, 10:11 PM
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#1 |
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3" Exhaust
Join Date: Jul 2007
Location: ohio
Posts: 90
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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.
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03-28-2010, 10:21 PM
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#2 |
 Toyota Racing Development Join Date: Apr 2007
Posts: 5,038
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Fuel pressure up and EGR vacuum control... and yes, you need them.
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03-28-2010, 10:25 PM
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#3 |
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3" Exhaust
Join Date: Jul 2007
Location: ohio
Posts: 90
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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?
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03-28-2010, 10:44 PM
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#4 |
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3" Exhaust
Join Date: Jul 2007
Location: ohio
Posts: 90
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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?
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04-10-2010, 04:54 AM
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#5 |
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Bone Stock w Upgrades ;-)
Join Date: Apr 2010
Location: Tampa Bay
Posts: 210
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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 Last edited by Bru; 02-09-2011 at 07:36 PM. |
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04-10-2010, 09:08 PM
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#6 | |
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Supra Forum Moderator
Join Date: Nov 2009
Location: Green-Ohio
Posts: 1,297
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Quote:
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 92 Ma71 7mGTE Auto. SafcII Supra FAQ Supra MKIII FAQ Classified Section guidelines : |
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04-10-2010, 09:54 PM
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#7 |
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Toyota Racing Development Join Date: Apr 2007
Posts: 5,038
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here's much more on that site too. Here's the link to the technical pages section: http://www.autoshop101.com/autoshop15.html
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If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar ---> |
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04-11-2010, 02:24 AM
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#8 |
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Bone Stock w Upgrades ;-)
Join Date: Apr 2010
Location: Tampa Bay
Posts: 210
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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. Last edited by Bru; 02-09-2011 at 07:45 PM. |
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04-11-2010, 07:24 AM
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#9 |
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Toyota Racing Development Join Date: Apr 2007
Posts: 5,038
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JDM Supras also use different timing and fuel maps which take the higher combustion chamber temps into account.
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If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar ---> |
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04-11-2010, 07:29 AM
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#10 |
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Supra Forum Moderator
Join Date: Nov 2009
Location: Green-Ohio
Posts: 1,297
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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.
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92 Ma71 7mGTE Auto. SafcII Supra FAQ Supra MKIII FAQ Classified Section guidelines : |
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