2005 STI Turbo Problem - Help

  • Thread starter Bryan Fenstermacher
  • Start date
B

Bryan Fenstermacher

All,

I have a new 2005 STI and have about 1300 miles on it. On Saturday I was
out driving it giving it a good ride, but nothing that would be considered
uncalled for giving that it's an STI.

Things seemed fine and didn't really notice any problems but five hours
later I went out and the car started up fine, but the turbo didn't seem to
be working properly.

The turbo boost gauge wasn't showing nearly enough boost in the lower gears
at lower RPM's. When you jumped on the gas the turbo would fire up and
shoot your forward with most of the power we were used too...

Also when you would let off of the gas you could hear a small and quiet
'whirr' of something spinning down. As soon as I would let off the gas the
boost pressure would disappear.

Any idea of what happened to my engine/turbo? There is no check engine
light on, or anything like that... Just the lack of getting shoved back in
your seat at the on the low gears (torque seems down), and the fact that the
boost gauge readings don't look good.

I have an appointment to take it to the dealer, I'm assuming they will pay
for it regardless.

Thanks,
Bryan
 
I have a new 2005 STI and have about 1300 miles on it. On Saturday I was
out driving it giving it a good ride, but nothing that would be considered
uncalled for giving that it's an STI.

Things seemed fine and didn't really notice any problems but five hours
later I went out and the car started up fine, but the turbo didn't seem to
be working properly.

The turbo boost gauge wasn't showing nearly enough boost in the lower gears
at lower RPM's. When you jumped on the gas the turbo would fire up and
shoot your forward with most of the power we were used too...

Also when you would let off of the gas you could hear a small and quiet
'whirr' of something spinning down. As soon as I would let off the gas the
boost pressure would disappear.

Any idea of what happened to my engine/turbo? There is no check engine
light on, or anything like that... Just the lack of getting shoved back in
your seat at the on the low gears (torque seems down), and the fact that the
boost gauge readings don't look good.

I have an appointment to take it to the dealer, I'm assuming they will pay
for it regardless.

Did you put anything less than 97 RON in it?

R
 
That 'wirr' could be a not working or sticky bov. This could explain the low
boost at low gears.
Maybe just a loose vacuum line of the bov.

SFC
 
I've been putting Sunoco 94 octane in it... Which I think is more than
fine.

-Bryan
 
SFC,

That is something I was thinking of, it feels like there is a leak somewhere
in the pressure of the turbo somewhere.

I was thinking (in my small knowledge of turbo's) that I thought the BOV
kept the pressure in for a short period of time to keep power on tap, and to
build some boost pressure prior to jumping on the gas so that the power will
come up quickly.

It also felt like the turbo overall didn't have as much boost pressure
overall as in the past, even when it was working.

Am I correct in how I'm describing the role of the BOV in the turbo system?

Thanks,
Bryan

From: "SFC" <(e-mail address removed)>
Subject: Re: 2005 STI Turbo Problem - Help
Date: Monday, July 26, 2004 1:24 PM

That 'wirr' could be a not working or sticky bov. This could explain the low
boost at low gears.
Maybe just a loose vacuum line of the bov.

SFC
Also when you would let off of the gas you could hear a small and quiet
'whirr' of something spinning down. As soon as I would let off the gas the
boost pressure would disappear.
 
The BOV allows excessive pressure to "blow-off" when you take your foot off
the gas (during shifts, when braking, etc, etc..). If it is stuck open it
will allow the boost pressure to be recirculated back to the intake instead
of going into the throttle-body. In other words it would act like a leaky
intercooler hose in some respects which would explain the lack of boost that
is building AND why it feels like there is less power being made.

I would start by having them check if the blow off valve is stuck open and
then maybe checking to see if you IC hoses maybe came loose or if, like
someone previously mentioned, that a vacuum line came off somewhere.
 
I have a new 2005 STI and have about 1300 miles on it. On Saturday I
was seem back

I have a WRX and the manual tells me not to put anything less than 95 RON in
it, it even says this on the fuel door. I normally use 97 and 98 RON. I
would expect an STI to run at higher boost therefor requiring higher ron
fuel to cope with the higher compression.

Using a low RON fuel does not allow as high a boost pressure due to the fuel
igniting before the spark. Id get the tank full of 97 at least then get an
ECU reset done at your dealer. Your timing may have been retarded
excessively to deal with the low RON fuel, you may also have damaged the
engine.

Ross
 
I have a WRX and the manual tells me not to put anything less than 95 RON in
it, it even says this on the fuel door. I normally use 97 and 98 RON. I
would expect an STI to run at higher boost therefor requiring higher ron
fuel to cope with the higher compression.

Using a low RON fuel does not allow as high a boost pressure due to the fuel
igniting before the spark. Id get the tank full of 97 at least then get an
ECU reset done at your dealer. Your timing may have been retarded
excessively to deal with the low RON fuel, you may also have damaged the
engine.

Ross

Doubtful you damaged the engine. A friend's 01 Passat 1.8T has used
nothing but 87 octane since new. Now at 120K no engine problems due to
that. Many many other problems but none octane related. No
manufacturer would produce an engine that can be damaged by wrong
octane. They would replace too many under warranty.
 
You want 97+ in there or you are just gonna be getting knock and the ECU
will whack back the timing and make it as slow as a pig - im forever getting
that when trying to run my GTFour on supermarket 95. The difference is
phenomenal.

J
 
And to follow up on what i said - they also dont like the fact that you have
hot intake temps due to the car sitting and heat-soaking the intercooler, so
the ECU will limit the boost until the IC cools down, which can take a
surprisingly long time > 15 mins on my car.

I ran some tests recently - my standard airbox reached >50C when stopped for
3 minutes, and never got back below low 40s in 20 miles of off-boost driving
after that. And thats before the turbo and IC.

J
 
Good explination of the bov function.
It could also be a ruptured membrane of the bov. Bosch (plastic) bov have a
bad rep of this.
Simple test: just suck on the vac. line which goes to the valve, if you
can't get any vacuum it's the membrane.

SFC
 
Where the heck do you guys get 97+ octane? The highest I can find is 94
around my neck of the woods (Central Ohio).

I think you might have a bit better performance, but can't imagine an engine
'NOT' running right as every idiot would be in getting their car serviced.

Have been running my 2.8L 5Valve V6 Passat for 90K miles on 92 Octane and
haven't ever had any engine problems or knocking. Runs like the day I
bought it...

-Bryan
 
Where the heck do you guys get 97+ octane? The highest I can find is 94
around my neck of the woods (Central Ohio).

Sorry, you are US - here in the UK we can get up to 98.9 ;) Thats what my
baby runs on, but at 6.25$ per imperial gallon its not cheap!
I think you might have a bit better performance, but can't imagine an engine
'NOT' running right as every idiot would be in getting their car serviced.

You want to check in the manual to see what it is meant to be run on. Mine
is supposed to run ok on 95 but it really doesnt for anything other than
grandad driving.
Have been running my 2.8L 5Valve V6 Passat for 90K miles on 92 Octane and
haven't ever had any engine problems or knocking. Runs like the day I
bought it...

Its not turbocharged, which makes allllll the difference to knock. And
generally you cant hear knocking that the ecu can so in all honesty it could
be and you just dont know it.

But since it runs fine in the first place then gets worse I'd look at my
other answer to your last post - it may be a combination of the two.

Try some octane booster in a tankful and see how much nicer she feels.

J
 
Sorry, you are US - here in the UK we can get up to 98.9 ;) Thats what my
baby runs on, but at 6.25$ per imperial gallon its not cheap!

In the US, we measure with the (R+N)/2 method, while most of the rest of
the world uses RON (the R part of R+N).

I don't have a conversion handy, but my '02 WRX wagon with the 2.0 turbo
requires 91 R+N/2 gasoline. Anything rated above 94 in the US is fairly
exotic race gas. In Phoenix, the highest octane I can find is 91 - and
we're only about 1000' (300m) above sea level. In New England (where
I'm from) you can easily find 93 and 94 octane as premium.

The RON only rating gives the fuel a numerically higher octane rating -
so I think WRX's sold out of North America require 95 RON which is about
the same as 91 R+N/2 fuel.
 
I have a WRX and the manual tells me not to put anything less than 95
RON in it, it even says this on the fuel door. I normally use 97 and
98 RON. I would expect an STI to run at higher boost therefor
requiring higher ron fuel to cope with the higher compression.

Your RON numbers aren't the same as our octane numbers here in the U.S. I
can't even *get* Sunoco 94 in the boonies where I'm at -- the best I can
find is 93 octane. AFAIK, Sunoco 94 is the highest-octane fuel you can buy
in the States without going to leaded race formulas or adding your own
octane boosters. The manual for my Forester requires 91 octane or higher.
While I haven't read the STi manual (not fortunate enough to own one), I'm
confident that the fuel he's using is fine.

- Greg Reed
 
I just replaced the turbo in my 02 wrx. (It was a good excuse to go
stage 4)I was experiencing much the same symptoms. Pull the turbo and
take a look inside the compressor housing. You may have a bad gasket
which would cause oil to leak into the housing and clog it up.
 
Where the heck do you guys get 97+ octane? The highest I can find is 94
around my neck of the woods (Central Ohio).

I'm not sure we are all speaking the same language. I think that
American 93 octane is equivalent to our (Godsown's) 98 RON.

Or something like that anyway

OTOH I could be wrong.
 
Bryan Fenstermacher said:
Where the heck do you guys get 97+ octane? The highest I can find is 94
around my neck of the woods (Central Ohio).

I think you might have a bit better performance, but can't imagine an engine
'NOT' running right as every idiot would be in getting their car serviced.

Have been running my 2.8L 5Valve V6 Passat for 90K miles on 92 Octane and
haven't ever had any engine problems or knocking. Runs like the day I
bought it...

-Bryan
RON.
You don't need 97 Octane. For one thing, in North America, octane is
measured as R+M/2. They are talking about RON; which is the Research Octane
Number (and its how they measure it in Britain). It is always higher than
the R+M/2 value. The MON number is usually lower than the RON, which is why
R+M/2 (also called AKI or Anti-Knock Index) is somewhere in the middle. 98
RON is approximately equal to 93.5 R+M/2. The owner's manual recommends 93
AKI (which is R+M/2) so you should be fine on Sunoco 94. However, Sunoco
does contain some ethanol, and though it shouldn't cause a problem, it will
produce slightly lower power than 94 AKI gasoline.

I suspect, as one poster suggested, that it could be you BOV, or you may
have a leak in the downpipe.
 
Byron said:
In the US, we measure with the (R+N)/2 method, while most of the rest of
the world uses RON (the R part of R+N).

I don't have a conversion handy, but my '02 WRX wagon with the 2.0 turbo
requires 91 R+N/2 gasoline. Anything rated above 94 in the US is fairly
exotic race gas. In Phoenix, the highest octane I can find is 91 - and
we're only about 1000' (300m) above sea level. In New England (where
I'm from) you can easily find 93 and 94 octane as premium.

The RON only rating gives the fuel a numerically higher octane rating -
so I think WRX's sold out of North America require 95 RON which is about
the same as 91 R+N/2 fuel.

actually, its RON+MON/2. Where RON=Research Octane Number and MON=Motor (I
believe, been told it mean Mechanical as well) Octane Number. It is rare to
find anything higher than 94 octane in US pumps using this method of
measuring octane. There are a few stations (Holiday in Minneapolis/St Paul
for example) that sometimes carry 100 octane street legal race fuel at the
pump.

You are right to assume that 95 RON is approximately the same as US 91/92
octane fuel.

http://www.elektro.com/~audi/audi/toluene.html has a pretty good explanation
on how this works, it also goes into detail on how to use Toluene as an
octane booster. I am not endorsing nor shooting down this idea, like any
other "mod" you do to your car or fuel, you are proceding at your own risk.
I personally use it in my car when I run high boost at the track, but others
may not feel comfortable using Toluene in their vehicles. Sorry for
hijacking this thread, this was the first article I could find that
explained RON+MON/2.
 
WRXtreme said:
actually, its RON+MON/2. Where RON=Research Octane Number and MON=Motor (I
believe, been told it mean Mechanical as well) Octane Number. It is rare to
find anything higher than 94 octane in US pumps using this method of
measuring octane. There are a few stations (Holiday in Minneapolis/St Paul
for example) that sometimes carry 100 octane street legal race fuel at the
pump.

You are right to assume that 95 RON is approximately the same as US 91/92
octane fuel.

http://www.elektro.com/~audi/audi/toluene.html has a pretty good explanation
on how this works, it also goes into detail on how to use Toluene as an
octane booster. I am not endorsing nor shooting down this idea, like any
other "mod" you do to your car or fuel, you are proceding at your own risk.
I personally use it in my car when I run high boost at the track, but others
may not feel comfortable using Toluene in their vehicles. Sorry for
hijacking this thread, this was the first article I could find that
explained RON+MON/2.

Just an add on... this stuff does work well ,but it is pretty hard on the
rubber parts of your fuel system ..
 

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