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Boost Pressure Leak?

Darren_S15

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Im sure this must have been asked before but I cannot find anything on it...

My engine is standard apart from an aftermarket exhaust manifold, and my boost guage is the factory one too.

Just been out in my car and noticed that the boost guage is only going to about 0.5 when my foot is fully down.

Im quite sure the guage should be reading more than this?

Im aware that the boost guage pressure pipe commonly splits and leaks pressure, but I have checked this (its some aftermarket silcone hose not the standard hose) and has no cracks or splits in it.

Anyone got any other ideas what I could check?

I guess the only thing Im aware of is cracks in the intercooler pipes?

Thanks

Darren
 
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Pazz

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Doesnt sound like a boost leak to me. Could be something stupid like accelerator not fully opening. Check that you have 100% of butterfly movement at pedal first.

Have you tried it in 4th/5th with foot flat on floor? Mine only reads 0.6-0.7kg/cm in 1st 2nd

but then I think stock is 0.7-0.8kg/cm????
 
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Yakozan

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Check that the stock boost solenoid is in place and properly connected.
Without it the car will only boost about 0.5bar unless you have an aftermarket boost controller.
 

Darren_S15

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I honestly cannot remember what gear I was in, 3rd or 4th I think.

My foot was fully flat and Im quite sure I was doing more than 5,000rpm when I was watching the gauge.

Ill check the solenoid and take the car for a quick drive later and let you know what happens.

I did not appreciate that the boost will not always get to max boost depending on what gear you are in.

Im hoping that its just me being stupid and it will boost past 0.5 later :|

Ill let you know how I get on,

Thanks
 
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Pazz

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It's not related to what gear you are in. It is just safer and easier from a testing point of view. A lot safer to be in 3rd etc than seeing what boost your hitting in 1st lol
 
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Matt_S

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What do they run as std with the restrictors and OE solenoid in place?

I dont know, you see (being a noob to S15s ;) )

But on S14s that run 10 psi (0.7 bar) WITH the boost solenoid and only 0.5 without it, it may be they are the same.
If youre only seeing 0.5 then Id say its the OE solenoid playing up, or you havent got one connected. WHich means its had a boost control on at some point and the OE parts not refitted.
 
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Matt_S

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It's not related to what gear you are in. It is just safer and easier from a testing point of view. A lot safer to be in 3rd etc than seeing what boost your hitting in 1st lol
Assuming its the same principle as S14s, they run actuator (0.5 bar) in 1st and 2nd and then 10 psi (0.7 bar) in 3rd upwards.
 
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Matt_S

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TBH if youre trying to see what boost a car runs you need to be in at least 3rd (maybe 4th on the 6 spd) to get a proper load on the motor.
 

Darren_S15

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Ive had a chance to take the car out and see what happens.

In no gear will the car boost over 0.5 :(

Took it to over 6,000 rpm in 3rd.

Ive checked the hose and its fine, the boost solenoid is connected fine too.

Is there a chance the solenoid can stop working or will this cause the car to not boost at all?

Ill check the butterfly later when I get a chance.

Anything else I can check?

Thanks.
 

Yakozan

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Try disconecting the solenoid harness. If you get a difference in boost it could be the actuator. No difference, and it's probobly a faulty solenoid.
I have one in the garage if you need one.

Edit: But I would recommend an aftermarket boost controller instead of the stock one if that is to blame for your boost problems.
 

Darren_S15

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Try disconecting the solenoid harness. If you get a difference in boost it could be the actuator. No difference, and it's probobly a faulty solenoid.
I have one in the garage if you need one.

Edit: But I would recommend an aftermarket boost controller instead of the stock one if that is to blame for your boost problems.
Is it OK/safe to drive around with the solenoid disconnected?

If it does turn out to be the solenoid what would you recommend I change it to as I have no idea about them?

And just before I do something silly can I just confirm we are talking about the thing circled in the photo below right?

 

Yakozan

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Is it OK/safe to drive around with the solenoid disconnected?

If it does turn out to be the solenoid what would you recommend I change it to as I have no idea about them?

And just before I do something silly can I just confirm we are talking about the thing circled in the photo below right?

No :)
That's the sender for the boost gauge.

The solenoid is located on your other strut tower and should have hoses going to the turbo, elephant trunk and IC-pipe :)
It's a tube looking thing.

Edit: damn, Nicely is fast today.
 

Darren_S15

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Im so glad you guys know what your doing :nod:

Right Ive found the solenoid, someone decided to move it in my engine bay.



Had a look at the connector and it was all guncked up with crap.

Given it a clean in the hope it might have just been this.

All the pipes have no splits and are well clamped onto the pipes.

Ill pop out in the car later and hope this might fix it.

Otherwise Ill have a go at disconnecting the solenoid and see what happens.
 
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Pazz

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More than likely the car has had an aftermarket boost controller fitted at some point in its life. Dunno why someone has mounted the stock solenoid back there tho :confused:
 
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Matt_S

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Darren. Drop me a PM with where you are etc. I have spare solenoids here if you want to try one of them.
 

Darren_S15

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Since cleaning the connector I did see my boost go very slightly over 0.5 which Ive not seen it do before.

But still not near 0.7.

Ill be trying some of the other suggestions now then...

Matt_S you have a PM.
 
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