Is the Fuel Pressure-Up VSV needed in my setup?

[MarkIII4Me]

I'm in the final stages of completing my ride and I recently discovered that one of the "mystery plugs" in my bay belongs to the Fuel Pressure-Up VSV. It's simple enough to install, but I have no idea what I did with the thing. I'm sure it's in one of my many boxes, but I don't want to go on a wild goose-chase finding something I may not even need; or may not even function properly in my setup.

Not sure if any of this info is relevant but I'm running a JDM ECU, HKS VPC, no EGR, Aeromotive AFPR, Denso pump and 550cc injectors. FFIM is provisioned for the CSI, bypassed the FPD on the rail.

Does the Fuel Pressure-Up VSV function properly in conjunction with a AFPR? Did JDM Supras run the Fuel Pressure-Up VSV? Will leaving the plug disconnected produce an error code?

Overall, should I install the VSV (once found) or omit the damn thing entirely?

I understand what it does, so if it'll work with my setup then I'll more than likely install it.

 

[IJ.]

My understanding is it increases FP for Hot Starts so can be a "good thing"

 

[MarkIII4Me]

It is my understanding that the Fuel Pressure-Up VSV redirects the vacuum source from the intake manifold to atmosphere during startups and keeps it open for around a minute before directing the pressure source back to the intake manifold. How will this affect the fuel pressure if I'm running an AFPR and the J-Tube is removed?

 

[IJ.]

It is my understanding that the Fuel Pressure-Up VSV redirects the vacuum source from the intake manifold to atmosphere during startups and keeps it open for around a minute before directing the pressure source back to the intake manifold. How will this affect the fuel pressure if I'm running an AFPR and the J-Tube is removed?

What I said but I believe it uses a temp signal from the ECU to decide when it's active ie: hot starts.

Not sure if I understand your question, it will remove the vacc signal from the backside of the AFPR giving a higher cranking fuel pressure, our engines don't get a "Prime" shot when you switch the Ign on they wait for a ref/sync event before the pump becomes active.

 

[MarkIII4Me]

Sounds about right. I wasn't aware that the ECU uses a temp signal to activate the vsv. So regardless of anyones setup, (short of running standalone), the Fuel Pressure-Up VSV should function correctly without affecting anything else? I mean, I kept the CSI for cold starts, might as well keep the vsv for hot ones

 

[IJ.]

I would

These cars can be a bitch for hot starts so I think it's useful.
(I'm 95% sure it's temp based but would need confirmation from JJ to be 100%)

 

[Nick M]

Two hundred degrees. Give or take. More like give. I will look in the book if I remember to do it.