Surge underload / weird boost

[Stacov]

Ok ill try explain as best as i can

 

2007 Subaru Legacy gt BP5 manual has 98k on the clock

 

whats happening most noticable in 4th and 5th is when u put the car underload and start boostin it starts to build boost and u can feel the car slight surging. While its doing this boost can drop off abit but if u take your foot off the off pedal and put it back on will boost to about 15psi Once it does this "note not all the time" it will limit my boost to 8psi and be stuck like that intill the ecu is cleared/reset

Once it has limited the boost to 8psi sport / sport sharp modes make no differences intill ecu is cleared

 

ECU isnt giving any codes apart from ABS c0140 which only showed up yesterday ?

 

Tryed to check all pipes and lines everything looks in good condition ?

Changed spark plugs in hope to fix my issue but no go

Has new air filter etc..

Car is stock standard apart from 2 rear mufflers

Running on BP 98 petrol

 

 

any help be great thanks finally brought this after years of not having a subaru and all was fine intill about 3 weeks ago when the surging came out of nowhere

Edited October 19, 2018 by Stacov

[Andy_Mac]

What hardware have you got for checking codes and connecting a laptop? A Learning View screenshot would probably tell all. 

Could be a variety of things without hard data but it's definitely pulling boost control and running wastegate pressure.

 

The pipe between the intercooler and throttle body is one that likes to cause issues, either tearing or popping off completely.

 

Did you buy it privately or through a dealer? That ABS code doesn't look like a fun one to try resolve.

[Stacov]

Hey Andy_Mac only pulling the codes off the dash, and once on a handheld reader at my local mechanics in dannevirke car was brought from car sales in hastings im the first nz owner.

 

[Andy_Mac]

Did they have a decent scan tool or just a code reader?

 

is there any kind of mechanical warranty on the car you can use to get them to foot the bill for the ABS fault? How long have you had the car?

[Stacov]

Was just a basic scan tool did give information but they said the auto electrician had a much better one,

 

i only opt for the 3 month warranty which is nearly up as its nearly been 3 months haha i havnt noticed any issues with the abs while driving tho so not sure why that code has come up.

 

Ill go back next week when everyone is open again, Was just trying to do everything i can do at home before i take it to someone to get looked at properly.

So pretty much without hard info from the ecu cant really find the issue.

 

Prob worth having some sort of scan tool when you own these sorts of cars im guess haha

 

thanks for your help man hopefully i get it sorted soon

 

[Andy_Mac]

I'd be hitting up the dealer ASAP. Even just to get it on record that these faults have arisen while under warranty. 

That ABS code looks to be a network communication error between the ABS computer and the main ECU from a quick search online.

 

Can get cheaper alternatives that do less, but these are awesome to have on hand. Can log any ECU parameter essentially. Only really needs to save you a couple of hours labour at a mechanic to pay for itself.

 

https://www.tactrix.com/

 

Or for phone connectivity one of the blue tooth options with this app.

 

https://www.btssm.com/?page=hardware

[Stacov]

yeah totally man i think investing in something like that would be totally worth even if u only use it couple times for logging or to check out the data.

 

Just had to shoot into town, was normal driving on the highway next minute car got faster out of nowhere boost had come back to 13.5/14 whatever its meant to be boosted it alittle in 5th to put load on car had no surge everything working fine, on the way home drove it little be harder and then went back to 8psi with the surge in 4/5 gear under load.

 

totally weird as