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Recently purchased 2000 B4- Troubleshooting flaws


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5 replies to this topic

#1 wasral

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Posted 23 June 2013 - 01:24 AM

Hi everyone,
I recently purchased a 2000 Legacy B4 Twin Turbo Manual Yesterday (22nd June 2013)
it
has 5 speed trans almost completely stock standard apart from a
aluminum wrx top mount inter-cooler and HKS SSQV BOV, the chap that sold
it to me also stated he replaced the factory ribbed turbo/inter-cooler
piping with silicon tubing for better airflow... He also stated he had
changed a few of the vacuum lines around to be the same as the 2003-20xx
models, I wasnt sure what changes ? not a subaru techi....

Onto the problems I am having...
The
engine has randomly turned itself off 3 times in the 1 day I have been
driving it, it seems to do it after being on boost and then coming up to
a stop when you clutch in to stop I will notice the engine just
shutting off and all the indication lights coming on as if reds were
on.. the lights I noticed (Check engine, oil light, Steering lights ect)
I simply put it into 2nd and clutched out to start again with no
dramas..
it only seems to turn off at low speed when almost stopped or when clutch is in only...
When I restart the car the "Steering" light above the temp gauge remains on, only when I pull over and turn the car all the way off and on does the steering light go away.

Secondly
I have a major I mean MAJOR brake shudder mostly only when braking at
higher speeds, you can barely feel it under 70km/h and cant feel it at
all under 50km/h but braking from 100 or over it shudders the steering
wheel violently going about an inch left to right. also if I let go of
the steering wheel the car will slowly drift off the the right...
this
worries me cause I hit a GIANT pot-hole on the way home with the car
yesterday. the front left wheel went right in there making a huge CRASH!
noise.. the rear left slightly went in on the edge but not as bad as
front. could I have cracked a disk or wheel?

Finally the boosting of the turbo seems really strange.. I will try my hardest to explain what its doing.
when
Im driving it usually starts boosting at 2000RPM getting to about 8PSI
just before the second turbo kicks in at 4000rpm then it kicks down to 0
psi for a brief second while the second turbo is engaged and begins
climbing back up where it gets to about 10PSI it doesnt seem to exceed
10 PSI with foot flat that lag period of no boost between first and
second turbo is no more then 1 second... I believe this is how its all meant to be?
then
randomly with no warning at all the first turbo will boost all the way
to 17PSI and when secondary engages it seems to lose its boost and real
slowly start climbing back up to 17-18PSI. when the car is boosting
17PSI the lag between the two turbos seems to last 3-4 second where it
feels boostless... what is causing my car to jump to 17PSI boost and
then back down to 10 other times? I do not have a boost tap/controller.

 


Any help would be greatly appreciated,
Cheers Trent.


Edited by wasral, 23 June 2013 - 02:22 AM.


#2 Fairtax4me

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Posted 23 June 2013 - 12:38 PM

When the first thing I read is "the P/O changed this" I immediately suspect that as the source of the problem.
I don't know if Subaru was using the ECU to control boost by that point, but there are still some functions that are purely vacuum controlled.
There should be a diagram on the bottom of the hood wih th proper vacuum hose routing dor that vehicle. If the car has it, you need to get the vacuum hoses as close back to stock as possible. I have an idea that all of your problems will be solved just by doing that.
People swap BOVs and ICs all the time, so those parts by themselves should not be the source of problems as long as the vacuum hoses that control the BOV are routed properly.

#3 wasral

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Posted 23 June 2013 - 03:58 PM

Cheers for your reply fairtax, sorry what do you mean the P/Os were changed? I dont have the vacuum diagram on the inside of my hood, it must have been removed? I only have the soft material padding there and even that has seen better days, i will look up a vacuum diagram online and try that, will see if that changes anything. Thanks

#4 Fairtax4me

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Posted 23 June 2013 - 04:13 PM

P/O = Previous Owner.
If the vacuum diagram is missing you may have a hard time finding the correct diagram.
If all else fails you may have to order an emissions hose routing label from Subaru. They will need the VIN to lookup the correct label.

#5 rxleone

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Posted 23 June 2013 - 06:09 PM

P/O = Previous Owner.
If the vacuum diagram is missing you may have a hard time finding the correct diagram.
If all else fails you may have to order an emissions hose routing label from Subaru. They will need the VIN to lookup the correct label.

 

 Do this. Anything the previous owner has done should be remedied before suspecting something factory. Also probably shouldn't be boosting to 17 PSI - I'd get that checked out ASAP, as that could be doing serious damage to your motor.



#6 WoodsWagon

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Posted 24 June 2013 - 02:05 AM

The stalling as you come to a stop could easily be the BOV. It's a MAF fuel injection system, so the computer is watching the air going in through the mass air flow sensor and fueling accordingly. The stock valve was a recirculating type, it dumped the excess pressure back into the turbo inlet and the MAF didn't see any more air getting sucked in. With an atmospheric BOV, the excess pressure is dumped out of the system and the turbos suck more air through the MAF to replace it.

 

What happens is the MAF tells the computer that a bunch of air is going into the engine while actually it's whooshing out the BOV. The computer dumps a bunch of fuel in to match the air that it thinks is going in, and it floods out the engine because that air wasn't there. You can drive to compensate for it, but it will always run filthy rich every time the BOV goes Psht.

 

The BOV can also not close properly during off-boost, which leads to an unmetered air leak into the intake system. That can cause it to run lean and stall.

 

With a MAF based EFI system a recirculating BOV is the the right way to go, but it doesn't make the cool noises as loudly so people don't use them.

 

The other thing to think about is to have a budget saved for repairs on the car in the future. I know it's not something you want to think about when having just bought it, but it has likely been flogged and that often leads to big ticket maintenance items later on.






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