mileage just disappearing

[ever_green]

well winter gas is upon us here in Ontario and my MPGs have suffered a good kick in the a$*. getting 19mpg now, down from 23mpg (all city). i would not mind if it wasn't for the fact that i did lot of coasting, driving without brakes, no idling (no remote start), and driving with load. just crazy how sensitive my car is to winter gas. it seems to just run so rich now that it's cold and for some reason when i drop to neutral going downhill my rpms climb to ~1300rpm instead of staying at 800. this only happens below 45mph & when Not stopped, and makes coasting in neutral completely pointless.

[Ecky]

I'm sure the cold itself is doing you no favors either. You could try more thoroughly sealing your engine bay perhaps?

[christofoo]

Originally Posted by ever_green

well winter gas is upon us here in Ontario and my MPGs have suffered a good kick in the a$*...

Winter MPGs will also drop with increased air density, primarily due to increased air drag but also due to increased throttle loss. 10% summer-winter variation is normal. (I'm not familiar with your vehicles though, no idea whether your results are normal.) However:

Originally Posted by ever_green

...when i drop to neutral going downhill my rpms climb to ~1300rpm instead of staying at 800. this only happens below 45mph & when Not stopped, and makes coasting in neutral completely pointless.

This symptom makes it sound like your engine temperature is cooling excessively. (Do you have a temperature gauge?) Toronto weather is just dropping below freezing now? I wonder if your thermostat is broken. First thing in the morning you can start it and open the radiator cap. If the coolant is still, it's okay, if you can see it circulating, the thermostat is stuck open. (At least on my Corolla, it's really obvious.)

Ecky may also have a point, grille blocking to increase engine bay temperature may be in order.

(Being where you live, do you have / use block heaters?)

[MetroMPG]

Block heater (if you have access to a plug) and a grille block.

And as has been pointed out, the winter fuel formulation is just one factor in many that is lowering everybody's fuel economy:

http://ecomodder.com/forum/showthrea...leage-220.html

[bestclimb]

Yep, was at 42 mpg, now struggling to maintain 38. Though less EOC due to a desire for heat. Do what you can but grin and bear it Some cars will idle higher in colder temps for some reason. I suspect more load on the alt due to heater fan on high, and perhaps emissions (more exhaust gasses to keep the cat warm?)

[ever_green]

actually i removed hood insulation pad because it increase my intake temp and because my engine gets hot. in about 5min my car reaches 70'c coolant temp, which is what subaru claims to be fully warm engine. 7-10min until the highest 88'c temp. so im not sure if heat is an issue here.

my afr map is fuel friendly 16:1 cruising under 55mph and 14.7:1 idle. i get 0.23gph according to SG2 warm idle. cold idle 0.6gph. under no circumstances afr goes under 14:1 unless over 4000rpm. throttle response seems excellent. my only issue is as though the gas is evaporating in there. i had to calibrate my sg2 to +10% as it was showing consumption to be too low! its usually around +3% in summer.

forgot to add that my car has a1200rpm closed loop cold start as well.

[brucepick]

Checked tire pressure lately? Measure when cold, and set to the sidewall imprint max.

[2000neon]

The cold weather certainly won't be helping. I'm just out of Waterloo and my mileage is dropping with the colder temperatures.

[serialk11r]

Strangely, winter gas is making my exhaust smell a lot nicer! As soon as I filled up with winter gas this time, the exhaust no longer smelled like someone was spraying gasoline straight into the air.

[arcosine]

19 mpg, Subarus suck at mileage, always lower than sticker. It's that stupid way too over square boxer engine.