Subaru 2000 Legacy Cold Start Problems

[Darradserv]

The car was manufactured in Canada, however the engine was replaced
locally before i bought it. My understanding is that it is a 2.5L
single cam. During warm weather the engine runs great. At 30 degrees it
fires irratic and then starts. When it is in the throws of starting the
engine check light flashes and the what I believe is the main relay
drops in and out. As it get colder it becomes much more difficult to
start to the point where at approximately 10 degrees F it plain will
not fire. At this point I get frustrated and start pulling sensors. At
temperatures above 10degreesF this seems to reset the computer and will
it fires and starts. I have replaced the coolant temp sensor to no
avail. I have brought the air temp inside to warm to no avail. In the
nether world of 10 degrees to 30 degrees disconnecting a sensor,
attempting to start seems to work with no regularity as to which sensor
(ie. air temp, coolant temp, purge solenoid, throttle valve). When the
car does start, it seems to fire on half it's cylinders for a bit as it
chugs to a point where I can finally give it enough gas without
stalling it. Once it starts, it runs beautifully no matter what the
outside temp is. My second hand understanding is that there is no spark
when it wont start. Not sure if the coil is powered. It seems to be
that the computer is not allowing it to fire. HELP! Please!

Sincerely, David

 

[Edward Hayes]

Simple as this sounds I would do it anyway. Remove all ground
connections, sand/clean and reattach. Do this not only to the battery
but, to ALL connections on the front spring/shock tower, starter and
engine block. Relays dropping out are a sign of low voltage either a
bad battery cell or poor connections. Let us know it or what helps
solve this issue. Ed

 

[Carl 1 Lucky Texan]

The car was manufactured in Canada, however the engine was replaced
locally before i bought it. My understanding is that it is a 2.5L
single cam. During warm weather the engine runs great. At 30 degrees it
fires irratic and then starts. When it is in the throws of starting the
engine check light flashes and the what I believe is the main relay
drops in and out. As it get colder it becomes much more difficult to
start to the point where at approximately 10 degrees F it plain will
not fire. At this point I get frustrated and start pulling sensors. At
temperatures above 10degreesF this seems to reset the computer and will
it fires and starts. I have replaced the coolant temp sensor to no
avail. I have brought the air temp inside to warm to no avail. In the
nether world of 10 degrees to 30 degrees disconnecting a sensor,
attempting to start seems to work with no regularity as to which sensor
(ie. air temp, coolant temp, purge solenoid, throttle valve). When the
car does start, it seems to fire on half it's cylinders for a bit as it
chugs to a point where I can finally give it enough gas without
stalling it. Once it starts, it runs beautifully no matter what the
outside temp is. My second hand understanding is that there is no spark
when it wont start. Not sure if the coil is powered. It seems to be
that the computer is not allowing it to fire. HELP! Please!

Sincerely, David

Have any codes been pulled from the ECU?
I THINK I recall some year/models having cold sensitive crank angle sensors.

good luck

Carl

 

[Vanguard]

The car was manufactured in Canada, however the engine was replaced
locally before i bought it. My understanding is that it is a 2.5L
single cam. During warm weather the engine runs great. At 30 degrees
it
fires irratic and then starts. When it is in the throws of starting
the
engine check light flashes and the what I believe is the main relay
drops in and out. As it get colder it becomes much more difficult to
start to the point where at approximately 10 degrees F it plain will
not fire. At this point I get frustrated and start pulling sensors. At
temperatures above 10degreesF this seems to reset the computer and
will
it fires and starts. I have replaced the coolant temp sensor to no
avail. I have brought the air temp inside to warm to no avail. In the
nether world of 10 degrees to 30 degrees disconnecting a sensor,
attempting to start seems to work with no regularity as to which
sensor
(ie. air temp, coolant temp, purge solenoid, throttle valve). When the
car does start, it seems to fire on half it's cylinders for a bit as
it
chugs to a point where I can finally give it enough gas without
stalling it. Once it starts, it runs beautifully no matter what the
outside temp is. My second hand understanding is that there is no
spark
when it wont start. Not sure if the coil is powered. It seems to be
that the computer is not allowing it to fire. HELP! Please!

Sincerely, David

Did I miss where you had the battery tested to determine if it has the
cold cranking amps needed at low[er] temperatures? Even if the car
starts, a weak battery can cause troubles with all the circuitry. My
alternator went bust so my battery wasn't getting charged while driving.
Before the battery was no longer able to do so, it could still start the
car but the electronics were screwed up (the running voltage was too low
because of the bad alternator). Did you put a voltmeter across the
battery before starting, during starting, and after starting to see what
voltage was available?