Firewall holes? [Merged] drill, drilling, pass-thru, wire, gauge, power, passenger

[siceclipse]

Let me guess, your MBC is connected to the BOV line?

Shut Up Bruce!

Even after our 3 talks on the phone and my problem being as stupid as a boost leak.(i hate you)
My MBC is STILL on the BOV line!

Take THAT!

as for everyone else reading this....

listen to Oldman

 

[LordZed]

This means what you have been seeing on the boost gauge is inaccurate, it's less than actual boost due to pressure bleed through the wastegate pressure relief hole, how much it has been off depends on the size of bleeder hole on the MBC. Which MBC?

It's a H.D. unit I constructed. I tapped it in before the MBC if it matters. It did not have a bleeder hole untill recently. It was just a ball and spring before I added the hole.(I added the hole this week and had to back the screw out quite a bit to get the same boost level) At any rate, it's getting changed tonight. I'll keep the MBC set to see the difference. It's set for 14 lbs right now. So we can see how much it's off. It can't be way off, or it seems my engine would have had a nasty reaction by now.

 

[oldman]

It's a H.D. unit I constructed. I tapped it in before the MBC if it matters.

I would certainly hope so , it's not too difficult to imagine boost readings if it was tapped on the wastegate line. 0...0....0.....0.....boom 16psi.

It did not have a bleeder hole untill recently. It was just a ball and spring before I added the hole.

If the mbc was contructed properly with no leaks around the ball or body of the MBC, no bleeder hole = no boost after shifting due to trapped pressure between MBC and wastegate after you let off.

Even after our 3 talks on the phone and my problem being as stupid as a boost leak.(i hate you)
My MBC is STILL on the BOV line!

If you enjoy having an open BOV under WOT, keep it on the BOV line.

 

[silver eclipse]

Isn't that what i said in the second post??

Yes, I did not mean to repost your information, but in post #8 he asked to reclarify so that he knew.
Even tho its sounds now like hes probly going to use the P port.
-Chad

 

[LordZed]

If the mbc was contructed properly with no leaks around the ball or body of the MBC, no bleeder hole = no boost after shifting due to trapped pressure between MBC and wastegate after you let off.

On that fact, how come it works if you have a straight line from the turbo to the waste gate? Wouldn't the same principle apply with trapped air? Just wondering, not doubting.

 

[Slow 95 TSI]

Although I would tap the line into another place other than the FPR line.

The line at the FPR is best to use it will give the most accurate signal. On a 2g it's by the master cylinder. The hose runs between the FPR & FPR solenoid it has a blue stripe on it.

 

[oldman]

On that fact, how come it works if you have a straight line from the turbo to the waste gate? Wouldn't the same principle apply with trapped air? Just wondering, not doubting.

No, a straight line is connected to the entire intake tract therefore the line pressure will rise and fall along with the intake tract, there is nothing to trap the pressure with. A ball and spring MBC is different, the ball is pitted against the inlet of the MBC by the spring blocking pressure from the wastegate actuator until the spring pressure is overcome. Let's say your MBC spring is set to 16psi, the ball is pushed open when the intake tract reaches 16psi, pressure is then release to the actuator which is rated let's say, 10psi, actuator then moves forward by 16psi worth pressure and open the wastegate flapper. As soon as you let off and intake pressure drops below 16psi, the MBC spring again pits the ball against the inlet and traps 15.9psi worth of pressure behind the ball and the wastegate stays open. This is why a bleeder hole is required between the MBC and wastegate on ball & spring type MBCs.

The line at the FPR is best to use it will give the most accurate signal. On a 2g it's by the master cylinder. The hose runs between the FPR & FPR solenoid it has a blue stripe on it.

Again, this is not the line you want, you want the line between the manifold and FPS, not FPS and FPR. The reason some think it's better to use the "p" port off the TB, or a dedicated source, is because if leaks were to develop on the line to the boost gauge or the gauge itself, you will not affect the pressure reference signal to the FPR which can have catastrophic consequences. This is also the reason why one should never use the BOV line as boost reference for the MBC, pressure bleed through the wastegate pressure relief hole we talked about up top will cause a pressure drop on the the BOV line causing the BOV to open under WOT.

 

[maxtsitalon]

Can anyone post pictures or describe the best place to drill through the firewall to run wires on a 1g talon.
My talon came with a power wire for my amp ran through the firewall, and its drilled directly under the passenger side windshield wiper mount and it runs through the dash and seems to curve left to the door and down the left side of the car under the carpet. i wanna run more wires through the firewall but don't wanna take the dash apart cause i can't seem to find the hole from the inside of the car. I know sounds confusing but any help would be great.

 

[98evoIIIpwr]

Steering boot is always a good option.

 

[maxtsitalon]

i saw post online about a grommet on the passenger side any pics of that?

 

[spoonman]

I took these pictures from my fire wall, I have no dash so it was easy to get them.

This picture is of the passenger side grommet that many of the wires pass through. I believe that to access the spot you must fold down the carpet and it is hidden behind the a/c heater core unit.

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This picture is of the steering column shaft grommet, it is very easy to get to.

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[maxtsitalon]

i believe i seen it from the engine bay. i'm just trying to run two 12 gauge wires through it. are they easy to pop out? or whats the process i guess.

 

[Dave532]

Sorry I can't give you a picture right now but I like to run brake lines and battery cables just to the right of the shifter cables (looking from the interior) as they come through the firewall. Not alot of room but enough for what you want to do I believe. The engine side of this area is obscured by padding which you can tear away.

 

[spoonman]

I believe this is what Dave is referring to, hard to access though, it is behind the center of the dash. My grommet area looks a little ruff but that is because I did a auto to manual swap and had to do custom cutting to the fire wall.

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[maxtsitalon]

which one is the easiest to run two wires through? the passenger side one? steering linkage one? or that one?

 

[joshs1074]

i found if you cut a short piece of tubing about 3/8" id with an angle cut so that it is pointed and stick it through the rubber boot and leave it there it becomes a handy chaseway. if you have to run bigger wires use a bigger piece of tubing.

 

[gdem69]

the by far easiest way to pass through the firewall is by undoing a metal hanger and make it straight. then look for a rubberized capping which is in the area of your battery and also your fuel filter on the gst and gsx model, its the same for the gs and rs models just that you have more clearance because your battery is on the other side. take your hanger and poke that rubberized capping you found on the firewall. now you found a direct way to pass wires from your engine bay and into your car. its tight to fit several wires but that hole has always worked miracles for me. save your time by not drilling a hole because its big enough to serve its purpose.

also to make it simple on all models the hole is through the passenger side so when you pass your wires through you will see them on coming through the passenger side floor (under the glove box)