I drove my 04 wrx to South Lake Tahoe for the first time since I
bought my car a few weeks ago. I'm in San Francisco at sea level, the
area of Tahoe I was at was about 5000+ feet above sea level. As soon
as I get to Tahoe, I notice a serious lack of power when I'm
accelerating from a stop. I understand that due to the thinner air at
higher altitudes, performance will decrease to a certain extent... BUT
my 4 year old nephew will out run me across an intersection (not that
I tried... but he could have)! :shock: It can take about 4 seconds
just to make it halfway through the intersection. Once I build up
speed, It'll be ok, but there is a SERIOUS lack of acceleration from
a stop.

First, I thought maybe my wastegate might be stuck open or something
from running 3000rpm for 2 hours, but when I drove home and got back
down to Placerville, my car accelerated near normal speeds... and
back in the nice, cold, dense foggy air of San Francisco, boy does it
accelerate.

I'm no expert in Subarus, or in turbos for that matter, but I thought
the ecu would use either the MAP sensor, or a baro sensor if it's
equipt with one to read atmospheric pressure and compensate.

I'm hoping someone can shed some light here on what might be going on.
I haven't found anyone else with the same problem online... and I
couldn't find any TSBs in this matter. For reference, I'm running
stock everything except for a SPT intake and exhaust... and
temperature is not the cause. It the same at 50 degrees, as it is at
85 degrees.

Any info that can help out here is much appreciated!

taz77 wrote:

> I drove my 04 wrx to South Lake Tahoe for the first time since I
> bought my car a few weeks ago. I'm in San Francisco at sea level, the
> area of Tahoe I was at was about 5000+ feet above sea level. As soon
> as I get to Tahoe, I notice a serious lack of power when I'm
> accelerating from a stop. I understand that due to the thinner air at
> higher altitudes, performance will decrease to a certain extent... BUT
> my 4 year old nephew will out run me across an intersection (not that
> I tried... but he could have)! :shock: It can take about 4 seconds
> just to make it halfway through the intersection. Once I build up
> speed, It'll be ok, but there is a SERIOUS lack of acceleration from
> a stop.
>
> First, I thought maybe my wastegate might be stuck open or something
> from running 3000rpm for 2 hours, but when I drove home and got back
> down to Placerville, my car accelerated near normal speeds... and
> back in the nice, cold, dense foggy air of San Francisco, boy does it
> accelerate.
>
> I'm no expert in Subarus, or in turbos for that matter, but I thought
> the ecu would use either the MAP sensor, or a baro sensor if it's
> equipt with one to read atmospheric pressure and compensate.
>
> I'm hoping someone can shed some light here on what might be going on.
> I haven't found anyone else with the same problem online... and I
> couldn't find any TSBs in this matter. For reference, I'm running
> stock everything except for a SPT intake and exhaust... and
> temperature is not the cause. It the same at 50 degrees, as it is at
> 85 degrees.
>
> Any info that can help out here is much appreciated!
>

I suppose it could take a few drive cycles - or resetting the ECU? -
before the system 'learns' the thinner air.


I dunno


Carl


--
to reply, change ( .not) to ( .net)

On Wed, 22 Aug 2007 22:04:12 -0500,
taz77tim@gmail-dot-com.no-spam.invalid (taz77) wrote:

>I drove my 04 wrx to South Lake Tahoe for the first time since I
>bought my car a few weeks ago. I'm in San Francisco at sea level, the
>area of Tahoe I was at was about 5000+ feet above sea level. As soon
>as I get to Tahoe, I notice a serious lack of power when I'm
>accelerating from a stop. I understand that due to the thinner air at
>higher altitudes, performance will decrease to a certain extent...

I live in greater Los Angeles and go from close to MSL to 5,000' AMSL
a lot. I have noticed no performance issues at that moderately high
altitude. I have an NA '07 Forester MT.

> taz77 wrote:
> I drove my 04 wrx to South Lake Tahoe for the first time since I
bought my car a few weeks ago. I'm in San Francisco at sea level, the
area of Tahoe I was at was about 5000+ feet above sea level. As soon
as I get to Tahoe, I notice a serious lack of power when I'm
accelerating from a stop. I understand that due to the thinner air at
higher altitudes, performance will decrease to a certain extent... BUT
my 4 year old nephew will out run me across an intersection (not that
I tried... but he could have)! :shock: It can take about 4 seconds
just to make it halfway through the intersection. Once I build up
speed, It'll be ok, but there is a SERIOUS lack of acceleration from
a stop.
>
> First, I thought maybe my wastegate might be stuck open or
something from running 3000rpm for 2 hours, but when I drove home and
got back down to Placerville, my car accelerated near normal speeds...
and back in the nice, cold, dense foggy air of San Francisco, boy does
it accelerate.
>
> I'm no expert in Subarus, or in turbos for that matter, but I
thought the ecu would use either the MAP sensor, or a baro sensor if
it's equipt with one to read atmospheric pressure and compensate.
>
> I'm hoping someone can shed some light here on what might be going
on. I haven't found anyone else with the same problem online... and I
couldn't find any TSBs in this matter. For reference, I'm running
stock everything except for a SPT intake and exhaust... and
temperature is not the cause. It the same at 50 degrees, as it is at
85 degrees.
>
> Any info that can help out here is much appreciated!

Well, I
know it is not normal for any car to accelerate like that... Subaru or
not. Turbo cars would probably notice a little more of a performance
decrease due to the turbo lag... but not that much. There were plenty
of WRX's there that out accelerated mine.

And resetting the ecu won't help. For one thing, most people won't
have the resources to know how to reset their ecu. Manufacturers
would have programmed some way for the ecu to updated while the
person is driving. I've heard going WOT at a low rpm should have
updated the ecu. Second thing, I already tried that. :wink: Tried
resetting the ecu in a couple ways, neither of which helped.

I was just hoping someone could verify my suspicion... I just won't
say what that is yet.

> > On Wed, 22 Aug 2007 22:04:12 -0500,
> > taz77tim@gmail-dot-com.no-spam.invalid (taz77) wrote:
> >
> > I drove my 04 wrx to South Lake Tahoe for the first time since I
> > bought my car a few weeks ago. I'm in San Francisco at sea level,
the
> > area of Tahoe I was at was about 5000+ feet above sea level. As
soon
> > as I get to Tahoe, I notice a serious lack of power when I'm
> > accelerating from a stop. I understand that due to the thinner
air at
> > higher altitudes, performance will decrease to a certain
extent...
> >
> David wrote:
>
>
> I live in greater Los Angeles and go from close to MSL to 5,000'
AMSL
> a lot. I have noticed no performance issues at that moderately
high
> altitude. I have an NA '07 Forester MT.

Oh yeah, I'm not familiar with the terms MSL and AMSL. Could you tell
me where the altitudes are 5000'? I might be heading down to LA, and
I'd like to test out a sensor at high altitudes.

"taz77" <taz77tim@gmail-dot-com.no-spam.invalid> wrote in message
news:6O-dnTej6bSD2VPbnZ2dnUVZ_jydnZ2d@giganews.com...
>
> > > On Wed, 22 Aug 2007 22:04:12 -0500,
> > > taz77tim@gmail-dot-com.no-spam.invalid (taz77) wrote:
> > >
> > > I drove my 04 wrx to South Lake Tahoe for the first time since I
> > > bought my car a few weeks ago. I'm in San Francisco at sea level,
> the
> > > area of Tahoe I was at was about 5000+ feet above sea level. As
> soon
> > > as I get to Tahoe, I notice a serious lack of power when I'm
> > > accelerating from a stop. I understand that due to the thinner
> air at
> > > higher altitudes, performance will decrease to a certain
> extent...
> > >
> > David wrote:
> >
> >
> > I live in greater Los Angeles and go from close to MSL to 5,000'
> AMSL
> > a lot. I have noticed no performance issues at that moderately
> high
> > altitude. I have an NA '07 Forester MT.
>
> Oh yeah, I'm not familiar with the terms MSL and AMSL. Could you tell
> me where the altitudes are 5000'? I might be heading down to LA, and
> I'd like to test out a sensor at high altitudes.

Mt. Wilson(5800), Angeles Crest Highway, Mt. High, Blueridge.Fraiser
Mountain(8000)
Lots more....but I dont buy this "it needs to learn the drive" stuff
either...


>

Sure your MAF is compensating for the SPT intake at the higher altitude?

Care to share your suspicion?

~Brian

"taz77" <taz77tim@gmail-dot-com.no-spam.invalid> wrote in message
news:6O-dnTSj6bSD2VPbnZ2dnUVZ_jydnZ2d@giganews.com...
>
> Well, I
> know it is not normal for any car to accelerate like that... Subaru or
> not. Turbo cars would probably notice a little more of a performance
> decrease due to the turbo lag... but not that much. There were plenty
> of WRX's there that out accelerated mine.
>
> And resetting the ecu won't help. For one thing, most people won't
> have the resources to know how to reset their ecu. Manufacturers
> would have programmed some way for the ecu to updated while the
> person is driving. I've heard going WOT at a low rpm should have
> updated the ecu. Second thing, I already tried that. :wink: Tried
> resetting the ecu in a couple ways, neither of which helped.
>
> I was just hoping someone could verify my suspicion... I just won't
> say what that is yet.
>

>
>Oh yeah, I'm not familiar with the terms MSL and AMSL. Could you tell
>me where the altitudes are 5000'? I might be heading down to LA, and
>I'd like to test out a sensor at high altitudes.

Here is a great place to check out a Subie at altitude, if you are
going to be anywhere near Big Pine, CA (US-395).
Just a few miles north of Big Pine, turn east on CA 168.
When you get to "White Mountain Road" turn north. The signage will
also say "Great Bristlecone Pine National Forest". The turn off is
about 13 miles off 395. The road constantly rises till you get to the
Visitor Center, which is at about 10,000 ft, At that point the paved
road ends, and turns into a good quality dirt road. It ends at a
closed gate which is about 12,000 ft. The road is only open from May
to November, depending on snowfall. Also, depending on when you go,
there may be an entry fee from the Forest Service.
Once a year you can go farther up the dirt road when UC Davis opens
the high altitude animal research station to visitors.

On Thu, 23 Aug 2007 21:36:14 -0500,
taz77tim@gmail-dot-com.no-spam.invalid (taz77) wrote:

>
> > > On Wed, 22 Aug 2007 22:04:12 -0500,
> > > taz77tim@gmail-dot-com.no-spam.invalid (taz77) wrote:
> > >
> > > I drove my 04 wrx to South Lake Tahoe for the first time since I
> > > bought my car a few weeks ago. I'm in San Francisco at sea level,
>the
> > > area of Tahoe I was at was about 5000+ feet above sea level. As
>soon
> > > as I get to Tahoe, I notice a serious lack of power when I'm
> > > accelerating from a stop. I understand that due to the thinner
>air at
> > > higher altitudes, performance will decrease to a certain
>extent...
> > >
> > David wrote:
> >
> >
> > I live in greater Los Angeles and go from close to MSL to 5,000'
>AMSL
> > a lot. I have noticed no performance issues at that moderately
>high
> > altitude. I have an NA '07 Forester MT.
>
>Oh yeah, I'm not familiar with the terms MSL and AMSL. Could you tell
>me where the altitudes are 5000'? I might be heading down to LA, and
>I'd like to test out a sensor at high altitudes.
Mean Sea Level and Above Mean Sea Level

State Route 2 between Glendale and Red Box Rd (goes to Mt. Wilson).
Santa Clara Divide Rd. between Angeles Forest and Little Tujunga is
right around 5,000'. Most of the highways in the San Bernardino
Mountains. And like that.

> > Well, one of my suspicion was that the perhaps with the SPT
intake, the MAF somehow wasn't detecting all the air entering the
engine, but I know there are plenty of people out there that have the
same intake. Probably cause they're afraid of voiding warranty. So
far, I have not heard of anyone with the same problem. I guess I can
compare the stock intake air flow volume compared to the SPT.
> >
> > Actually, if someone has a similar setup, and can tell me what
the MAF readings are at idle, and at 2000 rpm, I can compare it to
mine, and see if my MAF is reading the same.
> >
> > Sure your MAF is compensating for the SPT intake at the higher
altitude?
> >
> > Care to share your suspicion?
> >
> > ~Brian
> >
> > "taz77" <taz77tim@gmail-dot-com.no-spam.invalid>
wrote in message
> > news:6O-dnTSj6bSD2VPbnZ2dnUVZ_jydnZ2d@giganews.com...
> >
> > Well, I
> > know it is not normal for any car to accelerate like that...
Subaru or
> > not. Turbo cars would probably notice a little more of a
performance
> > decrease due to the turbo lag... but not that much. There were
plenty
> > of WRX's there that out accelerated mine.
> >
> > And resetting the ecu won't help. For one thing, most people
won't
> > have the resources to know how to reset their ecu. Manufacturers
> > would have programmed some way for the ecu to updated while the
> > person is driving. I've heard going WOT at a low rpm should have
> > updated the ecu. Second thing, I already tried that. :wink:
Tried
> > resetting the ecu in a couple ways, neither of which helped.
> >
> > I was just hoping someone could verify my suspicion... I just
won't
> > say what that is yet.
> > aa0]