'99 Legacy - smell of unburnt gasoline from exhaust

[MM]

Hi all,


It smells for a while after the start until the engine warms up. What can it
be? The car has passed emission test with no problem...


Thanks,
/MM

 

[Carl 1 Lucky Texan]

Hi all,


It smells for a while after the start until the engine warms up. What can it
be? The car has passed emission test with no problem...


Thanks,
/MM

Does it smell, like rubber or oil or 'toasted marsmallows' or ???
Is there any smoke? Are the fluid levels OK? CV joint boots intact?

Carl

 

[JD]

Hi all,


It smells for a while after the start until the engine warms up. What can
it be? The car has passed emission test with no problem...


Thanks,
/MM

Could be an issue with injectors. In a cold-cycle, the ECU ignores the O2
sensors and tries to guestimate 14.2:1 AFR. Once it warms up and starts
paying attention the the O2 sensor, everything should be normal. Other than
being a bit annoying, it probably won't do anything bad.

 

[weelliott]

Could be an issue with injectors.  In a cold-cycle, the ECU ignores theO2
sensors and tries to guestimate 14.2:1 AFR.  Once it warms up and starts
paying attention the the O2 sensor, everything should be normal.  Otherthan
being a bit annoying, it probably won't do anything bad.

I think this is actually normal. If the engine is cold, the car will
run rich. That is part of the startup algorythm,for the ECU. If it
continues after a few minutes of running, then you might have a
defective temperature sensor, I wouldn't worry about it.

Bill

 

[MM]

I think this is actually normal. If the engine is cold, the car will

run rich. That is part of the startup algorythm,for the ECU. If it
continues after a few minutes of running, then you might have a
defective temperature sensor, I wouldn't worry about it.

I've never noticed it with any of my other cars...

/MM

 

[MM]

Does it smell, like rubber or oil or 'toasted marsmallows' or ???

Is there any smoke? Are the fluid levels OK? CV joint boots intact?

It smells gasoline, I don't have a better word... With regards to the smoke,
I would say it looks more like dense steam, it doesn't seem to leave any
marks on the bumper... The fluids are OK, the boots I believe are too, and I
am talking about the car sitting in the driveway anyway...


/MM

 

[johninky]

When was the air filter last replaced?

 

[weelliott]

It smells gasoline, I don't have a better word... With regards to the smoke,
I would say it looks more like dense steam, it doesn't seem to leave any
marks on the bumper... The fluids are OK, the boots I believe are too, and I
am talking about the car sitting in the driveway anyway...

/MM

If it only does it when it is cold outside, then I BELIEVE it is
because the car senses that it is cold, and runs the engine a little
richer, which helps with cold starts. Both my 95 legacy and 90 miata
do this. The exhaust looks like steam and smells of gas. The legacy
has done it since I acquired it in 2001. It always passes emissions,
and only occasionally has the CEL on, which is pretty good for a
subie.

Once the ECU exits the startup sequence, the car will run closer to
stoichiometry. This rich-running during the start up sequence is why
'the experts' say it actually wastes gas to shut your engine off at a
stop if it is going to be off for less than 70 to 90 seconds.

The reason it is worse in cold weather is the colder air makes it
harder for the injectors to atomize the gas small enough to fully
combust. So you get unburnt fuel. This is actually the reason that
they need to put more fuel in-to make up for all the stuff that won't
burn. Once the head gets up to temp, the incoming air is warm enough
that the fuel will vaporize more easily. Consequently the smell of gas
goes away, and the extra fuel is not needed, which means the ECU sends
less gas. So then the exhaust stops smelling like gas.

I can't back this up with any sources, just a compilation of what I
have heard here and there. I really don't think there is anything to
worry about though. Cars simply run rich when the engine is cold.

 

[MM]

I really don't think there is anything to

worry about though. Cars simply run rich when the engine is cold.

I hope you are right, but none of the cars I've owned did it, or at least
not to the extent of this Subaru. And I owned Toyotas, Honda, Acura, and
Mazda... In fact I have a 2000 Honda Civic now and there is no comparison...
I probably should have mentioned that I believe that the fuel consumption on
this Subaru is too high. I am not confident because it has the infamous
intermittent speedo problem, which makes trip meter readings bogus. I am
working on getting that fixed, but I do have a feeling that I am at the pump
too frequently.


/MM

 

[MM]

When was the air filter last replaced?

Good question. I've just bought this car recently, so I will have to take a
look at the filter, although it hasn't popped up in the pre-sale inspection,
so it is probably OK.


/MM

 

[Carl 1 Lucky Texan]

I hope you are right, but none of the cars I've owned did it, or at least
not to the extent of this Subaru. And I owned Toyotas, Honda, Acura, and
Mazda... In fact I have a 2000 Honda Civic now and there is no comparison...
I probably should have mentioned that I believe that the fuel consumption on
this Subaru is too high. I am not confident because it has the infamous
intermittent speedo problem, which makes trip meter readings bogus. I am
working on getting that fixed, but I do have a feeling that I am at the pump
too frequently.


/MM

It may be a good idea to have the Engine Temp Sensor (not the temp gauge
sender) tested or changed. It can fail in such a manner the engine is in
'choke' mode all the time. Though people usually complain of poor
running after warm-up, it cerainly would use excessive fuel and may not
activate the check engine light.


Carl

 

[weelliott]

It may be a good idea to have the Engine Temp Sensor (not the temp gauge
sender) tested or changed. It can fail in such a manner the engine is in
'choke' mode all the time. Though people usually complain of poor
running after warm-up, it cerainly would use excessive fuel and may not
activate the check engine light.

Carl- Hide quoted text -

- Show quoted text -

I agree with Carl that if it goes on for too long after the car has
started, then the sensor might be bad, and causing the engine to stay
in the start-up mode. My wife's saturn had a bad temp sensor, and it
caused nearly impossible warm starts. I know it is a different car,
but if you have difficult warm starts, then perhaps the temp sensor is
bad.

I just looked at your original post. I read it and asumed you meant
one thing, but you coudl mean another. You say that it does it until
the car "warms up." I assumed that meant after the first minute or so
it goes away. If you mean it goes away after about 5 minutes of
driving, when the coolant temp gauge is well past the lowest mark,
then that is too long.

If it is taking a few minutes, then it is probably only going away
because the engine is warm, and able to burn the gas more efficiently,
thereby creating less unburnt gas in the exhaust, but still running
rich. It is not because the ECU has cut the amount of gas going in,
only because the gas is burning more efficiently. If this is the case,
I'd suspect the temp sensor that Carl mentioned.

Good luck,
Bill

 

[MM]

Thanks to everyone for all the advices. Are you talking about the coolant
temperature sensor (as shown here
http://www.lovehorsepower.com/SubaruDocs/CoolantTempSensor.html) or is there
another temperature sensor?

I will have to pay more attention to how long it takes for the smell to
disappear, but I believe it is there for quite a bit more than a minute...
It is difficult to judge though as after a minute one's nose loses its
sensitivity


Thanks,
/MM

 

[Carl 1 Lucky Texan]

Thanks to everyone for all the advices. Are you talking about the coolant
temperature sensor (as shown here
http://www.lovehorsepower.com/SubaruDocs/CoolantTempSensor.html) or is there
another temperature sensor?

I will have to pay more attention to how long it takes for the smell to
disappear, but I believe it is there for quite a bit more than a minute...
It is difficult to judge though as after a minute one's nose loses its
sensitivity


Thanks,
/MM

Hmmm...not sure. that is a '95 and may not have an ENGINE temp sensor.
usually, the 2 are near each other but i THINK the ETS has 3 wires. The
Coolant 'sender' has 2 (or maybe one plus ground?)

someone may know more about the physical aspects of this.

There are several ways the ECU can be confused and use too much fuel.
MAF , O2, engine idle solenoid(IAC?), maybe vacuum leaks, etc. for
instance. But if there is no CEL or OBDII code stored (that also returns
quickly when cleared) then I'd suspect the Eng. Temp Sensor.

Carl

 

[Ingo Menger]

Hi all,

It smells for a while after the start until the engine warms up. What can it
be? The car has passed emission test with no problem...

Same here with an '08 Outback 2.5i

The colder it is, the more it smells. (And this Winter it was really
cold ...)

Also, while the automatic transmission is in 'P', the motor RPM is
quite high. It goes down as soon as I shift to 'D'.

I always thought that this could have to do with the LPG add on, which
Subary gave away for free to new car buyers last year here in old
germany. LPG costs 65 ct., while Gasoline costs 120 and more, so while
fuel consumtion is 10% to 20% higher with LPG, this is still a big
win. It is clear that I drive with LPG whenever possible. Still, the
motor will be in gasoline mode when started and remain so until it
reaches a certain temperature.

 

[bugalugs]

Same here with an '08 Outback 2.5i

The colder it is, the more it smells. (And this Winter it was really
cold ...)

Also, while the automatic transmission is in 'P', the motor RPM is
quite high. It goes down as soon as I shift to 'D'.

I always thought that this could have to do with the LPG add on, which
Subary gave away for free to new car buyers last year here in old
germany. LPG costs 65 ct., while Gasoline costs 120 and more, so while
fuel consumtion is 10% to 20% higher with LPG, this is still a big
win. It is clear that I drive with LPG whenever possible. Still, the
motor will be in gasoline mode when started and remain so until it
reaches a certain temperature.

While not able to give a detailed technical description of how it works
I would say that with the transmission in P there is no load on the
engine. When shifting to D it loads up the transmission ready for the
vehicle to move off. You would get the same lowering of revs if you were
in P and loaded the engine by switching the Air Conditioning on high.

 

[Ingo Menger]

Ingo Menger wrote:


While not able to give a detailed technical description of how it works
I would say that with the transmission in P there is no load on the
engine. When shifting to D it loads up the transmission ready for the
vehicle to move off. You would get the same lowering of revs if you were
in P and loaded the engine by switching the Air Conditioning on high.

Sounds reasonable. Thanks for the hint.

 

[Hachiroku $B%O%A%m%/(B]

While not able to give a detailed technical description of how it works
I would say that with the transmission in P there is no load on the
engine. When shifting to D it loads up the transmission ready for the
vehicle to move off. You would get the same lowering of revs if you were
in P and loaded the engine by switching the Air Conditioning on high.

I just hold the throttle to the floor for about 45 seconds!

(NO, not really!)