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2G FPR Vacuum going through firewall

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mx3baker

Proven Member
95
25
Apr 27, 2017
Topeka, Kansas
My Vacuum line going to my FPR has a T that is running through my firewall, Would this be running to a gauge or somewhere else?

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Most likely to a boost gauge as that is a common point to tap for that.

As an FYI, some may recommend the tap should be moved and the FPR should have its own dedicated line, directly from the intake manifold.
 
Probably running to an aftermarket boost gauge. If you have an aftermarket boost gauge easy test is to unplug that line and start the car. If the gauge doesn't read anymore that's it.

Could also be running to a map sensor on a speed density set-up and someone decided to locate the sensor inside the car. People do weird stuff with these cars
 
Probably running to an aftermarket boost gauge. If you have an aftermarket boost gauge easy test is to unplug that line and start the car. If the gauge doesn't read anymore that's it.

Could also be running to a map sensor on a speed density set-up and someone decided to locate the sensor inside the car. People do weird stuff with these cars
Car currently does not run, im getting close but working on buttoning up a few things in the process.
I do have speed density, i have the 4 bar MAP installed in my intake so i assume the vacuum would not be going to another sensor.

Ill have to pull the boost gauge and see what the vacuum line running to it looks like, I assumed the boost gauge was ran from this clear tube coming from my intake.
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Most likely to a boost gauge as that is a common point to tap for that.

As an FYI, some may recommend the tap should be moved and the FPR should have its own dedicated line, directly from the intake manifold.
This is good news if it is running to my boost gauge, i wanted to relocate my FPR and the vacuum line was too tight. Id much rather pull it from the intake.
 
Is that clear tube also running through the firewall?

I guess the other question is where does the other end of your FPR hose (not running through the firewall) go to?
 
Is that clear tube also running through the firewall?

I guess the other question is where does the other end of your FPR hose (not running through the firewall) go to?
Yes the clear tube is running through the firewall

The FPR vacuum is ran to one of the 3 throttle body vacuum ports.
 
Ok - it’s all guesses on our part, then. Ultimately, you’re going to have to find out by digging in or doing some “testing”.

You can undo either of the lines running through the firewall, the clear one on the intake manifold or the one teed off the FPR, and blow low-ish pressure (just enough to read on the gauge) compressed air into each line separately while watching your boost gauge to see which is the source.

Without knowing what else is going on inside the car, not sure how else we can help.
 
Ok i appreciate the help. I was really just challenged on the line running from the FPR through the firewall. Ill trace the line and hopefully be able to remove it since its pretty crusty.
 
I attempted to trace the vacuum through the firewall, but it's high up in not sure I'll be able to figure it out without removing the dash...
I did confirm the clear tube goes to my boost gauge.
Here's a photo of the line from my FPR going to a hose through the firewall.

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The FPR vacuum is ran to one of the 3 throttle body vacuum ports.
That is fantastic way to not have enough volume of air get to the FPR so it can not raise fuel pressure 1:1 with boost as needed and blow the engine.

The nipple on the FPR should go direct to the manifold with a new rubber line and proper clamps. Do not mess around here.
 
I'm super curious where this hose runs to. I found one inside the car that runs under the passenger door carpet and back to the trunk area. No idea where it goes passed the back seat. Also unsure if this is actually the hose that the FPR vacuum is connected to, but seems like it might be.

Anyone know what the hose is for thats in the photos?

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