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The mkiv Supra Owners Club

Boost Gauge Constant Pressure Querry


monsween

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A bit of an odd one this. Had this problem for a year or two and searched but to no avail.

 

I have a boost gauge, boost controller, turbo timer and stock facelift boost gauge.

 

The 60mm Blitz one installed reads a constant pressure like a peak hold type thing. Its a mechanical gauge however and shouldn't hold this pressure. The boost controller i believe is plumbed into this and reads the same pressure digitally.

 

If i slightly put some power (no boost) down and lift off slowly then the pressure drops off the gauge/controller buy .09psi or so every time until its back to zero.

 

The stock boost gauge and turbo timer both read -ve and +ve as expected when running the car and don't have this issue.

 

The feed is from the intake manifold side (will get a picture tomorrow)

 

My guess is its been plumbed into a place where the pressure doesn't completed bleed off and i'm not correctly reading the turbo pressure.

 

Any other guesses?

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I would say you are indeed correct. The boost gauge shouldn't be plumbed into the controller, it should be plumbed into the manifold via a t-piece. I'm guessing that it was maybe done this way due to the inavailability of a t-piece. One of those jobs to "get round to" :D

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The boost gauge was there first and I think the Plebs plumbed the controller into the gauge. Will picture the feed tomorrow

 

They can read off the same line, but the boost controller shouldn't be in between the gauge and the manifold line. At least it should be an easy fix :D

 

Does that mean your boost controller has an out? Not seen that before lol.

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The boost controller has never been on. And i've no idea what "has an out" means lol

 

Right, this is sounding a bit of a bodge. Is it never on coz it doesn't work :D

 

By having an "out" I meant it has an output. In other words the manifold links to the "in" of the boost controller for it to monitor the boost levels but it also has an "out" for boost gauges and the likes.

 

I don't have an EBC and I haven't seen one in the flesh so I'm not really sure of how it works. In my head I can imagine the controller part having a boost sensor, this will be tapped into the inlet manifold to monitor the pressure. The controller will then look after the solenoid which is plumbed in between the actuator and the turbo, on off sort of thing.

 

Yours seems to be spaghetti'd in with the boost gauge which is strange.

 

Get some pics up :D

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I had the boost controller plumbed in because i was gonna go 1bar RR and 1.2bar with boost controller. With the 1bar RR im getting 1.2bar so their was never a need for it. When i get a new zorst i'll have to get it set up. Hence why it was never set up.

 

I went with a garage down your way that came recommended but wasn't happy with their work. I've contemplated taking out the fuel pump to make sure they fitted it. They have since went under.

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I had the boost controller plumbed in because i was gonna go 1bar RR and 1.2bar with boost controller. With the 1bar RR im getting 1.2bar so their was never a need for it. When i get a new zorst i'll have to get it set up. Hence why it was never set up.

 

I went with a garage down your way that came recommended but wasn't happy with their work. I've contemplated taking out the fuel pump to make sure they fitted it. They have since went under.

 

Who was it bud? I wouldn't go near anywhere near here.

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I'm still confused by all this.

 

That line coming off the mainfold... where does it go to? Does it split? 1 to the boost controller and one to the boost gauge?

 

From what you were saying earlier I thought it went to the boost controller and then a line went from the boost controller to the boost gauge?

 

The place where you have your manifold pressure line coming off of is perfectly normal, it's after that it all goes pete tong :D

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  • 4 weeks later...

Bumping this thread as i've got potentially a related issue here.

 

So......

 

All day yesterday i could only manage .8bar on second turbo, comes online fine at the right time just at .8bar max. However before when slowly accelerating i could "bleed" down the pressure my guage was seeing and get it back rather than having the constant pressue. Yesterday i couldn't. once the guage hit .8bar it stayed there.

 

This morning, driving to work the car was fine, boosting fine to 1.0 bar and this old bleeding down malarky was happening again. However driving home from the shops just now it went back to .8bar max and constant pressure rubbish.

 

One of the VSV's acting up perhaps?

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I'm still confused by all this.

 

That line coming off the mainfold... where does it go to? Does it split? 1 to the boost controller and one to the boost gauge?

 

From what you were saying earlier I thought it went to the boost controller and then a line went from the boost controller to the boost gauge?

 

The place where you have your manifold pressure line coming off of is perfectly normal, it's after that it all goes pete tong :D

 

 

:)

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I'm still confused by all this.

 

That line coming off the mainfold... where does it go to? Does it split? 1 to the boost controller and one to the boost gauge?

 

From what you were saying earlier I thought it went to the boost controller and then a line went from the boost controller to the boost gauge?

 

The place where you have your manifold pressure line coming off of is perfectly normal, it's after that it all goes pete tong :D

 

Completely overlooked this post (my bad)

 

Right, I'm gonna have to take the dash off sometime this week to find out where all the plumbing actually goes. Both the boost gauge and controller were fitted by 2 different garages (both i'd never go back to) So it well could be royally goosed. Once i get this worked out where everything goes i'll update again.

 

Was happenning again today with sometimes hitting .8 and then 1.15 and doing its bleeding malarky. Think i'm gonna replace the VSVs when im looking at the boost gauge/contoller set up as i have spares anyway and see what difference that makes.

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Completely overlooked this post (my bad)

 

Right, I'm gonna have to take the dash off sometime this week to find out where all the plumbing actually goes. Both the boost gauge and controller were fitted by 2 different garages (both i'd never go back to) So it well could be royally goosed. Once i get this worked out where everything goes i'll update again.

 

Was happenning again today with sometimes hitting .8 and then 1.15 and doing its bleeding malarky. Think i'm gonna replace the VSVs when im looking at the boost gauge/contoller set up as i have spares anyway and see what difference that makes.

 

 

I might be over simplifying things, without seeing what is going where it is hard to think of any reasons for your situation.

 

I'm guessing your gauge is mechanical? If that is the case they are very simple, all you should have going into the back of it is a manifold line (other than light feed). This should be directly from the manifold but it is very possible that it is split from the manifold leading into the back of the dash etc. The stock facelift has the stock boost gauge, my gauge is plumbed into that feed via a tpiece.

 

If it's an electronic boost gauge it will have a boost sensor (little plastic box with an "in" and wires coming out of it).

 

If there is nothing untoward with this setup, IE if the boost gauge is getting a direct feed from the manifold, or a t-pieced feed from the manifold, then the boost gauge itself is at fault. If the gauge is feeding from the boost controller (very strange) then IMO that would have something to do with the issue.

 

I'm not sure on how your boost controller is working? I might be over simplifying but I thought the boost solenoid was a solenoid and sensor in one? As in the pressure is measured at the turbo manfiold by the solenoid, when it hits x.xx bar the controller then actuates the boost solenoid to keep it constant? I didn't think the controllers required an additional boost line from the manifold to sense the pressure?

 

If you are ever down this way with the old girl bring it over and I'll have a look :)

Edited by Scott (see edit history)
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