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There are a number of tried and tested ways for measuring fuel
mixtures in your Subaru WRX fuel system that I will cover below and
the actuality is that other methods like cheap DIY meters, reading
tea leaves or consulting a psychic and these have no place in
Subaru performance tuning.
One of the keys to getting a
Subaru WRX with more power is the right ratio of
fuel for a given quantity of air. Either too much or not enough
fuel results in an engine that's down on power, delivers poor
economy and has a real question mark against its long-term
sturdiness. The primary job of the ecu tuner is to ensure that the
Subaru engine management system has been programmed to deliver fuel
in the proper quantities at any time.
![SubaruWRXRallyCar]()
Fuel mixture is measured in units of either Lambda
or air fuel ratio ( AFR ). Also referred in tune-speak as either
lean ( small amounts of fuel to air ) or rich ( large quantity of
fuel to air ). What is the correct mix of fuel and air? While there
is no such thing as an absolute across the board setting, the
sometimes concluded'golden rules' of fuel mixtures are :
1. At low power outputs (no boost) catalytic converter equipped
cars require a fuel mixture of Lambda 0.99 (AFR 14.64) for best
emissions, and is the target fuel mixture when the OE ECU is
operating in closed loop. Improvements in fuel economy can be made
by leaning fuel mixtures off to Lambda 1.05 (AFR 15.4 to 1), but
this is done at the expense of cat converter operation and will
increase exhaust temperatures when cruising.
2. Medium power outputs (the transition between on and off boost)
sees best power achieved at around Lambda 0.89 (AFR 13.1 to 1).
3. At high power outputs things get interesting, as this is the
area where the greatest potential for engine damage exists. Version
I to VI engines with stock internals running around 1.2 bar boost
typically make good power reliability at Lambda 0.78 (AFR 11.5 to
1). At the same boost pressure and with stock internals, Subaru WRX
Version VII and later models have redesigned cylinder head
combustion chambers for a very different set of burn
characteristics and fuel distribution compared to the previous
model, dictating significantly richer fuel mixtures of around
Lambda 0.75 (AFR 11.0 to 1) or lower to achieve best power
safely.
Generally air fuel ratios in your Subaru WRX fuel system can be
leaned slightly for a little increase in power on engines provided
with forged pistons, due to their strength and greater heat
resistance when put next to OE cast pistons.
Measuring Fuel Mixtures In Your Subaru WRX Fuel System
There are only 2 methods to check fuel mixtures precisely ; the
preferred technique is to use a top quality Subaru aftermarket wide
band air fuel meter in conjunction with a 5 wire Bosch LSU type
lambda sensor. This kind of sensor and meter can accurately measure
fuel mixtures from Lambda 0.69 ( AFR 10.1 to 1 ) to Lambda 1.30 (
AFR 19.1 to one ) and beyond. Hence the name wide band sensor.
An alternative strategy for cars with flash compatible ECUs such as
the Subaru Impreza WRX, fuel mixtures can be read right from the
ECU data stream using Delta Dash, with some exceptions. The OE
lambda sensor can'see' lean mixtures well, but cannot measure fuel
mixtures richer than Lambda 0.76 ( AFR 11.2 ). Additionally, at
power outputs higher than stock, sensor placement is an issue , as
exhaust back pressure between the engine and turbocharger causes a
serious decrease in sensor accuracy.
Learn how to select and fit the best Subaru performance parts for
the Subaru Impreza, Impreza WRX STi and the Subaru Forester to name
a few.
Finding and fitting suitable
Subaru aftermarket
performance parts doesn't have to be a challenge whether you
are working on used Subarus or want to modify a new Subaru.
Get a valuable insight into Subaru models from just about any
country in this top selling Subaru book.
Click Here to get Free Instant Access to the First 6
Chapters that will answer many of your Subaru questions.
Additional Information:
2008 Subaru WRX Sensor Failure
Understanding The 2004 Subaru Air Mass
Sensors
Subaru WRX Fuel Systems
Subaru WRX Fuel SystemDate Published: Dec 06, 2009 - 4:48 am
There are a number of tried and tested ways for measuring fuel
mixtures in your Subaru WRX fuel system that I will cover below and
the reality is that other methods like inexpensive DIY meters,
reading tea leaves or consulting a mystic and these have no place
in Subaru performance tuning.
One of the keys to getting a
Subaru WRX with more power is the proper
proportion of fuel for a given quantity of air. Either too much or
not enough fuel results in an engine that is down on power,
delivers poor economy and has a big question mark against its
long-term durability. The first job of the ecu tuner is to ensure
that the Subaru engine management system has been programmed to
supply fuel in the proper quantities at any time.
![SubaruWRXRallyCar]()
Fuel mix is measured in units of either Lambda or
air fuel ratio ( AFR ). Also referred in tune-speak as either lean
( small quantities of fuel to air ) or rich ( large amount of fuel
to air ). What's the correct mix of fuel and air? While there is
not any such thing as an absolute across the board setting, the
sometimes concluded'golden rules' of fuel mixtures are :
1. At low power outputs (no boost) catalytic converter equipped
cars require a fuel mixture of Lambda 0.99 (AFR 14.64) for best
emissions, and is the target fuel mixture when the OE ECU is
operating in closed loop. Improvements in fuel economy can be made
by leaning fuel mixtures off to Lambda 1.05 (AFR 15.4 to 1), but
this is done at the expense of cat converter operation and will
increase exhaust temperatures when cruising.
2. Medium power outputs (the transition between on and off boost)
sees best power achieved at around Lambda 0.89 (AFR 13.1 to 1).
3. At high power outputs things get interesting, as this is the
area where the greatest potential for engine damage exists. Version
I to VI engines with stock internals running around 1.2 bar boost
typically make good power reliability at Lambda 0.78 (AFR 11.5 to
1). At the same boost pressure and with stock internals, Subaru WRX
Version VII and later models have redesigned cylinder head
combustion chambers for a very different set of burn
characteristics and fuel distribution compared to the previous
model, dictating significantly richer fuel mixtures of around
Lambda 0.75 (AFR 11.0 to 1) or lower to achieve best power
safely.
Usually air fuel ratios in your Subaru WRX fuel system can be
leaned barely for a tiny increase in power on engines equipped with
forged pistons, due to their strength and larger heat resistance in
comparison to OE cast pistons.
Measuring Fuel Mixtures In Your Subaru WRX Fuel System
There are just two paths to check fuel mixtures precisely ; the
preferred methodology is to employ a top quality Subaru aftermarket
wide band air fuel meter in conjunction with a 5 wire Bosch LSU
type lambda sensor. This kind of sensor and meter can precisely
measure fuel mixtures from Lambda 0.69 ( AFR 10.1 to one ) to
Lambda 1.30 ( AFR 19.1 to 1 ) and beyond. Hence the name wide band
sensor.
An alternative method for cars with flash compatible ECUs such as
the Subaru Impreza WRX, fuel mixtures can be read straight from the
ECU data stream using Delta Dash, with some exceptions. The OE
lambda sensor can'see' lean mixtures well, but cannot measure fuel
mixtures richer than Lambda 0.76 ( AFR 11.2 ). In addition, at
power outputs higher than stock, sensor placement is an issue , as
exhaust back pressure between the engine and turbocharger causes a
significant decrease in sensor accuracy.
Learn how to select and fit the best Subaru performance parts for
the Subaru Impreza, Impreza WRX STi and the Subaru Forester to name
a few.
Finding and fitting suitable
Subaru aftermarket
performance parts doesn't have to be a challenge whether you
are working on used Subarus or want to modify a new Subaru.
Get a valuable insight into Subaru models from just about any
country in this top selling Subaru book.
Click Here to get Free Instant Access to the First 6
Chapters that will answer many of your Subaru questions.
Additional Information:
2003 Subaru Maintenance Schedule
Understanding The 2003 Subaru Air Mass
Sensors
Subaru WRX
Fuel System
Subaru WRX Fuel SystemsDate Published: Dec 06, 2009 - 3:28 am
There are a number of proven methods for measuring fuel mixtures in
your Subaru WRX fuel system that I will cover below and the reality
is that other methods such as cheap DIY meters, reading tea leaves
or consulting a psychic and these have no place in Subaru
performance tuning.
One of the keys to getting a
Subaru WRX with more power is the correct ratio
of fuel for a given quantity of air. Either too much or too little
fuel results in an engine that is down on power, delivers poor
economy and has a big question mark against its long term
durability. The primary job of the ecu tuner is to ensure that the
Subaru engine management system has been programmed to deliver fuel
in the correct quantities at all times.
![SubaruWRXRallyCar]()
Fuel Mixture is measured in units of either Lambda
or air fuel ratio (AFR). Also referred in tune-speak as either lean
(small amounts of fuel to air) or rich (large amount of fuel to
air). What is the correct mix of fuel and air? While there is no
such thing as an absolute across the board setting, the generally
agreed "golden rules" of fuel mixtures are:
1. At low power outputs (no boost) catalytic converter equipped
cars require a fuel mixture of Lambda 0.99 (AFR 14.64) for best
emissions, and is the target fuel mixture when the OE ECU is
operating in closed loop. Improvements in fuel economy can be made
by leaning fuel mixtures off to Lambda 1.05 (AFR 15.4 to 1), but
this is done at the expense of cat converter operation and will
increase exhaust temperatures when cruising.
2. Medium power outputs (the transition between on and off boost)
sees best power achieved at around Lambda 0.89 (AFR 13.1 to 1).
3. At high power outputs things get interesting, as this is the
area where the greatest potential for engine damage exists. Version
I to VI engines with stock internals running around 1.2 bar boost
typically make good power reliability at Lambda 0.78 (AFR 11.5 to
1). At the same boost pressure and with stock internals, Subaru WRX
Version VII and later models have redesigned cylinder head
combustion chambers for a very different set of burn
characteristics and fuel distribution compared to the previous
model, dictating significantly richer fuel mixtures of around
Lambda 0.75 (AFR 11.0 to 1) or lower to achieve best power
safely.
Typically, air fuel ratios in your Subaru WRX fuel system can be
leaned slightly for a small increase in power on engines equipped
with forged pistons, due to their strength and greater heat
resistance when compared to OE cast pistons.
Measuring Fuel Mixtures In Your Subaru WRX Fuel System
There are only two ways to check fuel mixtures accurately; the
preferred method is to use a high quality aftermarket wide band air
fuel ratio meter in conjunction with a five wire Bosch LSU type
lambda sensor. This type of sensor and meter can accurately measure
fuel mixtures from Lambda 0.69 (AFR 10.1 to 1) to Lambda 1.30 (AFR
19.1 to 1) and beyond. Hence the name wide band sensor.
An alternative method for cars with flash compatible ECUs such as
the Subaru Impreza WRX, fuel mixtures can be read directly from the
ECU data stream using Delta Dash, with a few exceptions. The OE
lambda sensor can "see" lean mixtures well, but cannot measure fuel
mixtures richer than Lambda 0.76 (AFR 11.2). Additionally, at power
outputs higher than stock, sensor placement is an issue, as exhaust
back pressure between the engine and turbocharger causes a
significant reduction in sensor accuracy.
Learn how to select and fit the best Subaru performance parts for
the Subaru Impreza, Impreza WRX STi and the Subaru Forester to name
a few.
Finding and fitting suitable
Subaru aftermarket
performance parts doesn't have to be a challenge whether you
are working on used Subarus or want to modify a new Subaru.
Get a valuable insight into Subaru models from just about any
country in this top selling Subaru book.
Click Here to get Free Instant Access to the First 6
Chapters that will answer many of your Subaru questions.
Additional Information:
Avoiding 2003 Subaru WRX Fuel Leaks
2007 Subaru Performance Tuning
2002 Subaru Sway Bar Modifications
Understanding The 2009 Subaru Air Mass
Sensors
Subaru WRX Fuel System HelpDate Published: Dec 05, 2009 - 4:23 pm
There are a number of proven methods for measuring fuel mixtures in
your Subaru WRX fuel system that I will cover below and the reality
is that other methods such as cheap DIY meters, reading tea leaves
or consulting a psychic and these have no place in Subaru
performance tuning.
One of the keys to getting a
Subaru WRX with more power is the correct ratio
of fuel for a given quantity of air. Either too much or too little
fuel results in an engine that is down on power, delivers poor
economy and has a big question mark against its long term
durability. The primary job of the ecu tuner is to ensure that the
Subaru engine management system has been programmed to deliver fuel
in the correct quantities at all times.
![SubaruWRXRallyCar]()
Fuel Mixture is measured in units of either Lambda
or air fuel ratio (AFR). Also referred in tune-speak as either lean
(small amounts of fuel to air) or rich (large amount of fuel to
air). What is the correct mix of fuel and air? While there is no
such thing as an absolute across the board setting, the generally
agreed "golden rules" of fuel mixtures are:
1. At low power outputs (no boost) catalytic converter equipped
cars require a fuel mixture of Lambda 0.99 (AFR 14.64) for best
emissions, and is the target fuel mixture when the OE ECU is
operating in closed loop. Improvements in fuel economy can be made
by leaning fuel mixtures off to Lambda 1.05 (AFR 15.4 to 1), but
this is done at the expense of cat converter operation and will
increase exhaust temperatures when cruising.
2. Medium power outputs (the transition between on and off boost)
sees best power achieved at around Lambda 0.89 (AFR 13.1 to 1).
3. At high power outputs things get interesting, as this is the
area where the greatest potential for engine damage exists. Version
I to VI engines with stock internals running around 1.2 bar boost
typically make good power reliability at Lambda 0.78 (AFR 11.5 to
1). At the same boost pressure and with stock internals, Subaru WRX
Version VII and later models have redesigned cylinder head
combustion chambers for a very different set of burn
characteristics and fuel distribution compared to the previous
model, dictating significantly richer fuel mixtures of around
Lambda 0.75 (AFR 11.0 to 1) or lower to achieve best power
safely.
Typically, air fuel ratios in your Subaru WRX fuel system can be
leaned slightly for a small increase in power on engines equipped
with forged pistons, due to their strength and greater heat
resistance when compared to OE cast pistons.
Measuring Fuel Mixtures In Your Subaru WRX Fuel System
There are only two ways to check fuel mixtures accurately; the
preferred method is to use a high quality aftermarket wide band air
fuel ratio meter in conjunction with a five wire Bosch LSU type
lambda sensor. This type of sensor and meter can accurately measure
fuel mixtures from Lambda 0.69 (AFR 10.1 to 1) to Lambda 1.30 (AFR
19.1 to 1) and beyond. Hence the name wide band sensor.
An alternative method for cars with flash compatible ECUs such as
the Subaru Impreza WRX, fuel mixtures can be read directly from the
ECU data stream using Delta Dash, with a few exceptions. The OE
lambda sensor can "see" lean mixtures well, but cannot measure fuel
mixtures richer than Lambda 0.76 (AFR 11.2). Additionally, at power
outputs higher than stock, sensor placement is an issue, as exhaust
back pressure between the engine and turbocharger causes a
significant reduction in sensor accuracy.
Learn how to select and fit the best Subaru performance parts for
the Subaru Impreza, Impreza WRX STi and the Subaru Forester to name
a few.
Finding and fitting suitable
Subaru aftermarket
performance parts doesn't have to be a challenge whether you
are working on used Subarus or want to modify a new Subaru.
Get a valuable insight into Subaru models from just about any
country in this top selling Subaru book.
Click Here to get Free Instant Access to the First 6
Chapters that will answer many of your Subaru questions.
Additional Information:
Understanding The 2001 Subaru Air Mass
Sensors
2009 Subaru Scheduled Service
2005 Subaru Performance Tuning
2004 Subaru WRX Sensor Failure
Subaru WRX Fuel System HintsDate Published: Dec 05, 2009 - 2:46 pm
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Date Published: Dec 05, 2009 - 9:00 am