Hi All,

Can anyone with an STi7 using factory boost control confirm whether there is supposed to be a join in pipe between t-piece and the solenoid please?

The car I recently logged at only .9 bar (thinking this was normal for a standard STi I've read and logged a few more cars since then ) turns out to have a join here....that's partially melted...blocking flow to the solenoid....

Fixing this gets boost back as per a normal car. But instead of the usual 10-13 degrees advance 'knock correction' at 5k7, it's getting -3 or -5 degrees

Car pulls OK up to this limit (and knock signal is off) and I've heard of a few WRX's requiring new knock sensors.

But I'm very suspect of the melted join - why would Subaru put a plastic join right above the turbo?!

If it is OE, then I'd also like to know how it melted - the only modification the car has is a high-flow 100 cell cat in place of the original one (in original downpipe). Of interest, 100 cell isn't enough to keep the CEL off...200 cell next

Richard

 

If you mean between the T-piece and the boost control solenoid, then yes, there is a black connector there in the pipework. Mine is a factory JDM STi 01.

I have removed this, replaced the pipes and now use a flow control valve instead of a restrictor - this seems to work pretty well.

The knock correction might mean you are *over* boosting?

 

Hi Bret,

After messin about with a few co's I finally have a flow control from Festo on its way It should be getting here in a week or so. I will be using your diagram and info to set it up, thanks again for help !

How is your car running, is the valve holding consistent or are you having to adjust it constantly ?


Cheers,
Ray

 

Richard , Thats the "other restrictor" . Black plastic thingy . Enlarging gives more boost , smaller = less boost .

Ray

 

...and when melted closed it gives .8-.9 bar

Thanks all - checked another 7 yesterday to confirm.

Question is, why did it melt? And why is it also retarding *bad* above 5k7? It's fine below that, with no audible det (even while retarding above 5k7).

If the engine got hot enough to melt plastic, what else has been damaged

Richard

 

That plastic thingy controls boost as well ? Not another variable to add to the mix

Bret, I noticed that you took yours out when you put in the adjustable flow valve.....I presume there were no negative affects of removing this plastic 'restrictor' ?

Cheers,
Ray