03 WRX Boost query? Help please.

[Madhou5e]

Hello,
A long time lurker but I need some assistance please.

03 WRX. Standard other than Haywood & Scott system and fuel pressure regulator.
Normally boosts at around 14psi but has dropped off to about 8psi. Was intermittent but now only 8psi.
Disconnecting the BCS the car will boost quick and happy (although I haven't driven any distance or not allowing boost to go too high)

So I've got hold of another BCS which I thought would blitz it however, not so. Still only seeing around 8psi.

I'm wondering if there is a boost leak as there is a feint whistle as it spools up so my question is where should I be looking please before I start pulling things apart?

Any help would be appreciated.

Cheers
Mark.

[Mortster]

Are you sure there's not a leak in the pipe to the boost gauge?

I had a similar thing to this, had the intercooler off, checked everything etc etc.

Changed the boost gauge, then by chance checked the t-piece....had a tiny split, just enough to make the gauge under read.

[Madhou5e]

I'm pretty sure the boost gauge is ok. Without the BCS connected the boost will shoot up happily. Plus the car is not as 'aggressive' as it should be either boost wise it's there...just not how it should feel.

[Scott.T]

Sounds like the ecu has limited boost due to a running issue.
It has the ability to cut boost if it detects detonation.
If the maf is going bad it will cause detonation due to lean running.
Its worth plugging the car in to check the IAM (ignition advance multiplier)

If you have an obd cable you can do this with Romraider or Ecuedit.

[Madhou5e]

Originally Posted by SilverSurfer

Sounds like the ecu has limited boost due to a running issue.
It has the ability to cut boost if it detects detonation.
If the maf is going bad it will cause detonation due to lean running.
Its worth plugging the car in to check the IAM (ignition advance multiplier)

If you have an obd cable you can do this with Romraider or Ecuedit.

Crumbs. I don't have access to any of those things unfortunately. The car starts runs and drives fine aside of this boost thing.
Where is the MAF located and does a clean with carb cleaner help?
Is there any other issues an iffy MAF would show?

Cheers
Mark.