Hi Olds Folks, new member here. I purchased a 2001 Aurora two years ago that has an odd problem.I live near Lake Erie and the fuel milage difference between warm and cold temps is terrible, warm weather 20+, cold weather 12 avg. Engine with in specs. syn oil 5-30w, new air filter,maintenance by the book and tires air pressure maintained. I can see losing a couple of mpg due to winter formula for gas and other winter climate factors, but 10 miles avg per gallon. I live in a small town so not much stop and go, hills not problem. Anyone else living under these climate conditions having this problem? thanks and God Bless.

 

What temp. is the car running at when it is cold?

 

The difference begins to show up when the temp drop into the mid 30's and the info.center confirms an avg mpg of 11. I believe the engine is not getting enough air through the intake, but the engine runs well and does not smell like it running rich. I've also tried 93 octain, no improvement so far. What could I be missing here, besides the air filter compartment,is anyone familiar with the lower part of the air box. thanks. I have the 3.5L V6 and hate to take the air box apart blindly. Thanks for any and all help.

 

The difference begins to show up when the temp drop into the mid 30's and the info.center confirms an avg mpg of 11. I believe the engine is not getting enough air through the intake, but the engine runs well and does not smell like it running rich. I've also tried 93 octain, no improvement so far. What could I be missing here, besides the air filter compartment,is anyone familiar with the lower part of the air box. thanks.

 

Mike,

Does the math (mileage / gallons) agree with what the DIC reads on the avg?
I would think that if the engine is really running that much richer, some trouble codes (too rich) would be set, unless the system is running open loop. In that case, another then code should be set after a while, meaning being in open loop too long... Of course this computer stuff is kinda beyond my knowledge...

I assume it does reach normal operating temp?

 

Usually the cause of poor gas mileage in the winter is when the car is left idling for long periods of time to keep the inside warm. Burning gas without wheels turning = poor mpg. Winter air is (duh) cold and more dense which most engines like. I agree with Rob, check your actual mpg. Winter running does decrease mpg simply because the running gear needs more time to warm up, and stays "stiffer" for longer amount of time. Using 93 octane just means you're paying more per gallon. Unless your car requires super premium I wouldn't use it.

One more thing just hit me. Don't know how many miles on this car, but think about having your 02 sensors checked. If they're sending wrong info to the cars computer, it can cause problems with fuel economy too. There should be 2 on your car: one in the exhaust manifold, and one by cat. BTW 02 sensors are cheaper to buy on the web than going to a dealer if that's the problem.

Definitely check and replace your air filter if required. Don't forget to changeout the PCV valve too. Lots of time this gets overlooked.

 

If your thermostat is too cold, it will cause the engine to run richer than normal. If this is the problem the car would never reach normal operating temp.

 

Yes cars get lower MPG in the winter due to warm up and cold air, but not by that much.

I'd start with a new air filter, and if that doesn't do the trick, new plugs, maybe new wires, and a fuel fiter change.

K&N is also an improvement over a stock air filter, moves more air

 

In Washington state the fuel mixture is changed in the winter months to lower emisions (so they say) this lowers the MPG during the winter months

 

I second Citcapp. In Illinois (at least the Chicago area, and I think the metro east around St. Louis), the fuel mixture is changed for winter (increased oxygenates, I was told, supposedly to help reduce pollution, since the cold air can trap it next to the ground for days on end). My 2004 Vue (Honda V6) drops off by anywhere from 5-10 MPG per tank (worst when it is real cold), down to around 10 or 11 at times, in city driving. The falloff isn't as bad on the road. Some of this is due to increased warm up and idling etc, but the same thing used to happen with my 94 Cutlass Supreme convertible that had the 3.4 DOHC V6. The explanation I read somewhere a few years ago is that the increased oxygenates in the exhaust passing by the O2 sensor cause the computer to dump more fuel through the system. There may be less pollution from oxides of nitrogen this way, but there is probably more from unburned hydrocarbons getting through. Anybody else see this? I think maybe it was in Car and Driver at the time, but it has been several years and I may not be remembering it all correctly.

 

thanks to everyone for the help, as soon as it's warm enough for me to look under the hood I'm going to look at everything again and refill the gas tank,record milage from tank to tank,did this before and computer was correct. If the computer and hand computing jell I will replace the oxygen sensors. One step at a time. I will say it is a great summer car, fuel milage highway 30+, town 20+, there's that 10 again.

 

I've noticed a very similar trend with my '01 as well. Summer months I get 22-24mpg average, now I average 16-19mpg. I do not start the car and let it sit, just get in and go. In the summer I run the A/C, right now I am running the heat and driver heated seat.

 

X2 I'm not sure about gasoline, but fuel is blended to avoud gelling, my economy is aproximately 55% off my peak in summer months. You may also want to considder rolling resistance. IE, tire pressure, and fluid viscosity. I'm comming from a trucking mindset, where these variables can make huge differences in power output, and resistance. Cold air is denser, so theoretically you should be producing more power, all other things being equal. Check alignment, tune, tire pressure. internal resistance can be reduced by using synthetic lubes, and fluids. Fuel is fuel, about the only thing you can do there is shop around for a supplier that has the "better" stuff. There is adifference from supplier to supplier as far as addatives go. As an aside avoid citgo, and petro fuel unles you want to put money ito hugo chaves' pocket. No sence supporting someone who hates America and everything it stands for, especially when he is trying to get nukes.

 

Oddly enough I don't seem to have a wide variation on fuel consumption on the '99 I am driving right now...I use about 5 or 6 litres to go 45 minutes on the expressway with about 5 minutes of that in stop and go traffic...to and from work..so the total is 11 or 12 litres.. the '96 used about the same amount and it had about 300K kilometres The temp the past couple of days has been minus 14 to minus 18...and the only extra fuel I use is for idling...