I get 430-450 city/highway in my 98 coupe.

 

i am getting around an average of 28-29 in city driving and 32+ on the highway, 96 lx 2.2 5speed 194,444 miles, in your case though, oil getting into the plugs sounds like a vavle cover gasket and making a slight misfire of your spark plug, which would drop you mpg

 

Once during pure interstate driving, got between 40 & 41 mpg with the '03 Accord (4-cyl 5-spd). I was behaving myself & the weather wasnice.Traffic was heavy so I was following a line of trucks - not much acceleration was possible.

The tank is 17 gallons so that's about 680 miles till it's completely sucked dry.

With a coupe it's a bit lighter & maybe less aero drag. I had lots of stuff in the car (moving my daughter) so an empty car would do better.

So... 600 miles on a tank is believable, but not real easy to do all the time in all kinds of weather.

 

I get about 20 mpg city driving and around 25-28 highway thats with 219k. I usually squeak right at 400 miles per tank.

 

22-23 mostly city. not bad for all the miles on this car. not too good for a 4 cylinder, but she's got plently of kick at 220,000 miles.

 

I have low gas mileage when driving in town, ~200 miles per fillup. I still haven't figured out why my mileage sucks when driving in town. I don't drive aggressively, tire pressure is within spec, etc. I am trying to figure out what is going on, and I will post when I come up with a solution.

When I am on the interstate, I get 400+ on a full tank. When I hit light traffic througout the trip I got 500 miles on one tank.

 

I have read recently of gas theft. You would know since they would have to jimmy the fuel cover to access the fill cap.

Our cars are virtually identical mechanically, except you have MT and I have AT. I get 25-27 mpg around town w/o any special effort. Lately I've been slowing down, watching start/stops, and increased tire pressure to 35, but too early to discern any measurable improvement.

Something must be wrong w/ your Accord; tire misalignment, excessive brake drag, fuel leakage (check fuel injector seals carefully as leakshard to spot, tank crack), fuel pressure regulator, O2 sensor old? Any possibility you're buying 15% ethanol? That would probably reduce mileage by about the same amount. I assume you are in tune and clean air filter?

Is 200 miles per tank for a 10, 12, or 14 gallon fill-up. My fillups average around 12 gallons, somewhere between 1/4 and Empty.

Regards

 

The poor gas mileage is starting to frustrate me.

My fillups are ~13 gallons. The fuel pressure is within spec with FPR connected and disconnected. The tires are only 3 months old, and the car was aligned then. I will check the calipers for dragging. I need to redo my compression test (with the throttle wide open this time).

I am going to monitor the fuel pressure while driving again with the gauge I rigged up. I will set up a new post with some more details. I was thinking about replacing the gaskets in the exhaust system, check for any cracks while I am down there, and take a look at the cat. The bolts on the back of the cat seem pretty rusted, but I should be able to get them off. I will probably have the valves adjusted.

The O2 sensor is new, but I have had a code 43 pop up ocassionally, especially when it is cold. TAS auto said that they would send me a new one under their warranty if my fuel pressure was within spec. I might send the fuel injectors off to get cleaned as well.

 

At your present gas mileage, the loss is 5 gallons per fillup or $17.50/ fillup, and only about 15 mpg. That's a lot of fuel going somewhere. This suggests a leak or really excessive rich mixture.

An exhaust leak upstream of O2 sensor might cause ECU to supply extra fuel to richen the mixture. This is where OBD2 comes in handy to monitor the fuel trim levels. If your's is doing this you should have a very positive long term fuel trim. Honda service centers or shops specializing in Hondas might be able to determine if fuel is being lost by erroneous O2 sensing.

good luck

 

Any exhaust leaks after the secondary O2 sensor shouldn't affect your mileage.

Texas, if the ECU was richening up the mixture, wouldn't his car bod down under acceleration somewhat like clogged EGR ports would do?


BTW, I just did my firt mileage calc with my new 6th gen: 33.8 MPG, but I think it's somewhere closer to 32. This is much better compared to the 24 MPG I would get in the 5th gen with the same amount of WOT runs...