which vsv is which?

zachm611

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Hi everyone i bought my supra a while ago and both vsvs were broken at the connection just dangling off the vacuum line so i took them off and just ran a hose to both ends sorta by passing it i guess. I bought a parts car a not too long ago and the harness has a VSV on it but i dont know which one it is, is there a difference or any way to tell between the fuel pressure up vsv, and the egr vsv? (parts car had JDM engine is it safe to assume its the fuel pressure up vsv?)is it going to hurt to not run one? thanks a lot,

Zach
 

jdub

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The two VSV's are the same...the forward one on the manifold is the high temp fuel pressure up VSV. It is vented to the atmosphere when 12 volt power is applied (from the ECU) to it:
Fuel Pressure up VSV
The FP up VSV purpose is for starts with a High OAT...in the summer, it can be a problem depending on where you live.

The EGR VSV is mounted on the rear of the manifold. It operates and can be tested the same way:
EGR VSV

My '89 wiring diagram shows a red/black stripe wire going to the fuel pressure up VSV and a red/blue stripe wire going to the EGR VSV.
 

jetjock

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Running no VSV on the EGR will result in it being on when it shouldn't. Running without one on the FPU system will result in it not working. Of the two the EGR issue is the bigger "problem".
 

suprabad

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Running no VSV on the EGR will result in it being on when it shouldn't. Running without one on the FPU system will result in it not working. Of the two the EGR issue is the bigger "problem".
I guess that would depend on whether being stranded on a hot day (when you go to restart your car) or clogging up your EGR valve is more important to you.
 

jdub

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Clogging up the EGR is not the issue...
 

zachm611

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I have my egr blocked off as it was leaking before. but thanks for the VSV help everyone.