Cobb AccessPort "economy" setting

[Brandon]

Hi everyone. I recently bought a new Legacy GT (I had a 1993 Impreza
with 172,000 miles before) and am thinking about buying a Cobb
AccessPort. I am interested in the extra power I could get out of it
but after filling up my gas tank for the first time, I think I would be
interested in giving the "economy" map a try too. I live in a hilly
city and my work is probably less than three miles away so my gas
milage going to and from work is pretty appalling. My only questions
is how much of an increase in fuel efficiency could I get out of the
AccessPort? Other posts about the AccessPort said that increases in
gas milage were pretty minimal but I don't know if any of them gave the
"economy" map a try. Any input?

-Brandon

 

[mulder]

Hi everyone. I recently bought a new Legacy GT (I had a 1993 Impreza
with 172,000 miles before) and am thinking about buying a Cobb
AccessPort. I am interested in the extra power I could get out of it
but after filling up my gas tank for the first time, I think I would be
interested in giving the "economy" map a try too. I live in a hilly
city and my work is probably less than three miles away so my gas
milage going to and from work is pretty appalling. My only questions
is how much of an increase in fuel efficiency could I get out of the
AccessPort? Other posts about the AccessPort said that increases in
gas milage were pretty minimal but I don't know if any of them gave the
"economy" map a try. Any input?

-Brandon

Perhaps the economy map would provide some marginal improvement in
mileage, but this is not the purpose of the Accessport. It is for
increasing performance on stock setups and to provide modified engine
management for bolt-on upgrades. If saving gas is all you have in mind
then I suggest you save your money. Besides, for what an Accessport
will cost you can buy a lot of gas so it would take a very long time
to conceivably break even.

 

[JD]

Perhaps the economy map would provide some marginal improvement in
mileage, but this is not the purpose of the Accessport. It is for
increasing performance on stock setups and to provide modified engine
management for bolt-on upgrades. If saving gas is all you have in mind
then I suggest you save your money. Besides, for what an Accessport
will cost you can buy a lot of gas so it would take a very long time
to conceivably break even.

Agreed. The economy map sets the BOV pressure to zero. So it effectively
disables the turbo. You still have to use 91 octane minimum (because the
timing is so aggressive) so it will really only improve gas mileage on the
highway and when it is hot out. But, because you are disabling the turbo,
there is a warning against 'spirited' driving with the economy map. You can
damage the engine. Turbocharged engines typically have a lower compression
ratio than normally aspirated, and our scoobies are at between 8 and 8.2:1

 

[mulder]

Agreed. The economy map sets the BOV pressure to zero. So it effectively
disables the turbo. You still have to use 91 octane minimum (because the
timing is so aggressive) so it will really only improve gas mileage on the
highway and when it is hot out. But, because you are disabling the turbo,
there is a warning against 'spirited' driving with the economy map. You can
damage the engine. Turbocharged engines typically have a lower compression
ratio than normally aspirated, and our scoobies are at between 8 and 8.2:1

A bit of correction here. It isn't possible to electronically "disable
the turbo" and the BOV or actually BPV is not controlled by the ECU at
all. You are thinking of the boost control solenoid, and the most that
can be done with that is to reduce its duty cycle so it is always
closed. This will reduce the maximum boost pressure to the wastegate
setting which is probably around 7-8 psi (at least on the WRX it is).
This would not result in engine damage, it would actually be safer,
but there would be a loss of power. There may be other factors
involved with what Cobb does in their economy map, I have not read
their documentation.

 

[Brandon]

Right - if I bought an AccessPort, it would be for the performance
gain, not the gas mileage. But being able to get some extra gas
mileage at times would only sweeten the deal and make me a little more
likely to poney up the $600+. I was just wondering if anyone had
actually tried the economy map on Cobb's site and how much of an effect
it had - in the city and on the highway. Anyone?

 

[Carl 1 Lucky Texan]

Right - if I bought an AccessPort, it would be for the performance
gain, not the gas mileage. But being able to get some extra gas
mileage at times would only sweeten the deal and make me a little more
likely to poney up the $600+. I was just wondering if anyone had
actually tried the economy map on Cobb's site and how much of an effect
it had - in the city and on the highway. Anyone?

You could try simulating the effect of an 'economy' map by driving 2-3
tankfuls and NEVER revving over 4K.

Carl

 

[Bob H]

www.legacygt.com

Right - if I bought an AccessPort, it would be for the performance
gain, not the gas mileage. But being able to get some extra gas
mileage at times would only sweeten the deal and make me a little more
likely to poney up the $600+. I was just wondering if anyone had
actually tried the economy map on Cobb's site and how much of an effect
it had - in the city and on the highway. Anyone?

 

[JD]

A bit of correction here. It isn't possible to electronically "disable
the turbo" and the BOV or actually BPV is not controlled by the ECU at
all. You are thinking of the boost control solenoid, and the most that
can be done with that is to reduce its duty cycle so it is always
closed. This will reduce the maximum boost pressure to the wastegate
setting which is probably around 7-8 psi (at least on the WRX it is).
This would not result in engine damage, it would actually be safer,
but there would be a loss of power. There may be other factors
involved with what Cobb does in their economy map, I have not read
their documentation.

The electronic boost control is set to 0 PSI. The turbo still spools but
there is no pressure beyond the 100 KPa of normal atmospheric pressure.
However, once the turbo spools, it is ambient and not in vacuum like an N/A
car (off boost, at below 2000 RPM and no acceleration, an STi runs at around
56 KPa).

There is a warning from Cobb about the economy map; they say it because the
timing advance is still very aggressive (close to 48 degrees on an STi), and
no boost pressure. In open loop (ie. WOT) you will be dumping fuel in like
it was turbocharged.

You still have to use 91 or better, and they warn against spirited driving.
If this was not an issue, and it just reduced the power, they wouldn't need
to warn anyone about anything.

 

[nobody]

www.legacygt.com

Legacygt.com doesn't work.
Double checked it; no DNS (Domain Name Service) on it with or without
the 'www'. (fancy geektalk for "It's dead, Jim")

 

[Blair Baucom]

Legacygt.com doesn't work.
Double checked it; no DNS (Domain Name Service) on it with or without the
'www'. (fancy geektalk for "It's dead, Jim")

Just loaded for me here is the USA.

Blair

 

[sarahs choice]

Just loaded for me here is the USA.

Blair

It works in Australia.

Here is a post from the forum

"Some people may have noticed an "expired domain" site up this morning.
My registrar made a mistake in resetting my DNS when they renewed my
domain for another 3 years, yesterday. They have corrected the mistake
but DNS will still take a little time for some people to propigate.
Sorry for the confusion."

-Tide