Had a bit of a problem yesterday with my 93 WRX, top radiator hose split on the way to work, was only a few miles from home so was still in warm up mode, i.e. less than 3K revs gentle driving off boost.

Whilst waiting for the replacement hose to arrive back at home I decided to take the manual boost controller off as it has been screwed right down (as far as I know) due to the car having been fitted with a Scoobyecu, so decided it wasn't required and removed it. I connected the 2 ends of pipe together and thought no more about it, well until this morning Car is only boosting to 0.5 bar now where as normally it goes off of my Lamco gauge, which goes up to 1.1 bar.

So the question is, if the MBC is screwed right down and it's removed and the pipework directly connected is it possible for this to affect the boost level, i.e. even with it screwed fully down does it still bleed off some air?

 

have you got any orange lights on the dash?

with the mbc screwed right down u must of been boosing quite a lot! i have a mbc which is only screwed in a small amount and it still boosts up2 1.1bar...

Only reason i can see you boosting to 0.5 is because ur car is in limp mode or have a leak somewhere or your boost solenoid that you reconnected back up is full of **** n not functioning correct

what other mods you have?

Bri

 

no lights on the dash.

The MBC was on the car when I bought it, the previous owner had decatted it and used the MBC to set the boost to 1 bar, thankfully.

As I understand it the boost level is controlled by the Scoobyecu, so was under the impression the MBC had been screwed in as it wasn't really required to do anything anymore. Couldn't really understand why it wasn't just removed if it wasn't doing anything so decided to remove it. It would now seem like I may be wrong and it does actually do something even when it's screwed shut, was just hoping someone could confirm that.

Don't know what you mean about the boost solenoid, I didn't mention anything about that, I haven't touched it.

Mods wise, other than the Scoobyecu which was mapped by Pat, it's got a full decat, green panel filter and resonator box has been removed, that's it.

 

well without a mbc, your boost if controled by a solenoid, which is controled by the ecu.... what did you do with the 2 vac pipes when you took away the mbc? by the way, if the mbc was screwed right in it means your boost was turned up and the device was being used...

 

There were 2 connections on the MBC so when I removed it I just joined the 2 ends together to make 1 continuous pipe from end to end.

hmmm, looks like I might have things a bit back to front here then, perhaps in future I'll ask first before removing things, will stick it back on tonight and see what happens, cheers

Note to self, if it ain't broke, don't bloody touch it

 

yeah thats wrong how you have connected the 2 pipes back up.....

them 2 pipes are actually part of a trio, the 1 that you didnt know about is actually your boost solenoid pipe, and will be hidden somwhere out of the way with something blocking the hole as its not needed when connecting a MBC

it will be best to connect mbc back up, especially if you had the car mapped with the mbc on.

cheers,

Bri

 

I've put the MBC back on and everything is working sooper dooper again, full boost. Not sure I really understand how that works but I'm past caring now, as long as it's working, I ain't touching it again