I've got a 1999 2.3l VTEC EX 4-door sedan and over the past couple of years I've been surprised by the vast differences in warm and cold weather mileage. I'm in Minnesota and we do have cold winters, yet I've never experienced seasonal differentials that have exceeded 1 or 2 MPG. In the winter the car consistently gets 23.5 MPG and in the spring and fall I get 28.5.

The car was little-old-man driven for 10-years with very regular dealer maintenance and with only 55K miles, it made a great purchase for me. I've done the basic maintenance; plugs, air and oil filters, no stored trouble codes, checked for vacuum leaks. I would probably ignore this issue, but this is my winter car so the cold weather mileage is the most relevant.

If it is of use, last spring when it came out of storage it wouldn't idle as something was probably stuck. After simply running the engine with a fast idle until it warmed, the idle problem never came back. I have been considering cleaning out the EGR ports?

Anybody else experiencing nearly 20% fuel economy losses from season to season? If you're a winter cold weather resident, what MPG's do you see? Or best yet, do you have a suggestion on what I can do to improve it?

 

Fellow Honda lovers, Pam is a little disappointed. With 183 views over the past month, is it true that not one of you is a northerner like me and willing to share your warm/cold weather mileage experiences with your Accord? Remember, the real Pamela was a Canadian.

Or, maybe everyone was just looking for a few new girlie pics?

 

I spend way more money on gas in the winter, sucks but such is life...

 

Ive lived in Texas and California so the weather doesnt change enough to check this.




Hotweatherproblems.

 

I have the same issue (96 sedan, 4cyl, no vtec). Haven't resolved it yet. I feel extremely luck on the odd tank I get 26mpg in the winter, usually more like 23ish.

Do you use different tires in the winter? different tire sizes can change your odometer reading and affect your mpg calculations, not to mention snow tires aren't as fuel efficient as summer tires.

My summer mileage didn't come back as far after I got new summer tires the same size as my winter tires. They aren't quite the right size and I figured based on stock size I am losing about 5% of my miles displayed, ie I go 105 miles for every 100 it shows on the odometer.

The next thing i'm going to try replacing is my ECT, mainly due to I have suspicions about it working properly for other reasons, but if it's a little off it could be causing you to burn more fuel on startup than necessary. (it could be just a fuel gauge issue but it seems I lose more on starting the car than I do driving for a while) I also plan to clean my EGR runner as troubleshooting for an intermittent rough idle which could also be related. Haven't got to it yet though.

What I HAVE done:
New plugs (NGK iridium), wires (NGK), cap and rotor (OEM from majestic honda), valve adjustment, K&N stock replacement air filter (not CAI), changed to top tier gas only (mostly chevron - I notice even in the summer I can lose 4 or 5 mpg by putting cheap gas in the car for more than a tankful at a time), running mobil1 oil. Not all of that was specifically to troubleshoot this issue but it all might affect mileage. The only thing that seemed to make much difference was what brand of gas I put in.

My o2 sensor seems to check out OK but I'm strongly considering replacing it sometime as well. Even if it works mostly correctly, if it's a little slow it can make a difference.

 

Thanks very much "Spokane" for giving me something concrete to chew on and to you other guys also. I drive the same all seasons all year, yet the car is parked during the summer anyway. Good idea, though, and I know you are right about how different tires and inflation can affect mileage. I haven't experienced issues with different fuels and o2 sensors I've come to believe they're good for something around 100K miles, then kick them down the road.

Your discussion about replacing your ECT got me thinking, but I haven't decided on the best way to prove my hypothesis yet. There are a couple coolant temp sensors according to my docs:

1) coolant temp gauge sending unit
2) ECT sending unit / ECT sensor

Here's the thought. Since I see the dash temp gauge riding in a reasonable and consistent position at different air temps I assume the old stat is fine. Maybe #1 in my list sends this signal to the dash? Yet, the other sensor could be malfunctioning and causing the engine to run unnecessarily rich (or at least inefficiently) in the winter.

I welcome your thoughts, but even without, thanks very much for getting me thinking.
Pam

 

blame the oil companies. anywhere it gets below about 40F there is winter blend gas and summer blend gas. plus air is denser when its cold so it requires more fuel to burn at the right air/fuel ratio. you could try a good fuel system cleaner too like redline, it's helped me in the past.

 

There are two sensors under the distributor, the one wire sensor tells ur dash the temperature, the two wire sensor is the ECT. Warm the car up and test for resistance on the two wire sensor. It should be somewhere between 200 and 400. You could also replace the Intake Air Charge sensor which senses intake air charge temperature. Those are like 15 bucks anywhere.