Ok guys, I ran out of solutions, I really need your help

[jayliu1984]

Originally Posted by AndrzejM

Check spark plugs and lambda sensor. I know probably for such short commutes engine will stay in a open loop but I think that Accord has heated lambda. You may check inlet manifold for leaks, and exhaust as well.
If I'll think of something more I'll post.

What do you look for on spark plug and O2 sensor? There is no Check Engine Light, so beside to see if it is visually dirty, how do I know if they are affect anything?

This car is pretty new, 2009, do you think it is possible to have manifold leak and how do I even go about checking it?

[redpoint5]

Originally Posted by jayliu1984

I am not sure if this is an honest mix up, or you are making fun of me. But that fella is me.

My apologies Jay; I was sneaking in a forum visit during a boring meeting at work and didn't pay enough attention. I just knew the problem sounded familiar.

[ChazInMT]

Hey Bud, I'm pretty sure when you have it on defrost the AC compressor runs to condense moisture inside the cabin and defog the window during rainy days. I think it's supposed to know when it is below 35-40°F (2-5°C..eh) and not run the AC, but I've always been suspect of that. So, be sure you're not running defrost unless you gotta. And don't recirc the air either, this will cause your windows to fog up, recirc only on crazy hot days or when you're going by a pig farm er sumthin. I see people drive by all the time all fogged up and would bet real money they're recircing the air.

I could be wrong about the AC shutting off at what temp or if it even does. But I'm certain the AC comes on when at 50°F & above when you have it on defrost.

[2000mc]

Did you have the civic with your current commute? Mpg w/ the civic?

With my old commute i did alot of 40-45 mpg tanks. I had a tank under 20mpg this winter, but I have a short commute now and don't think there's anything wrong with the car.

[jayliu1984]

Thanks for all the replies guys. Can you please, when you suggest what to check, include what I should look for.

How do I check a O2 sensor? I can take it out and then what? I am sure it won't be shiny but how do I know if it is affecting my mileage.

Or spark plugs, what do I even look for?

[hungryhunter]

Originally Posted by nackerton

What kind of automatic tranny it has? Has its oil ever been changed? Block heater and grille block would help with short trip MPG especially in winter..

I know the newer ATX are better but you're still slipping until lockup in the final gear. 4 cyl are most affected on a % mpg basis. Don't compare MTX and ATX fuel economy.

[aardvarcus]

Just to illustrate my comment on a cold engine using more gas, this morning I did a few tests. There are some good places for me to Pulse and Glide, so while my car was in neutral idling, I checked the temperatures and fuel consumption. There were three cases:
Car was cold, only running about a minute. Engine was at 32 F and Intake 32 F. Car consumed 0.70 – 0.75 gallons per hour coasting in neutral.
Car was partially heated up, running about 8 minutes. Engine was at 160 F and Intake 36 F. Car consumed 0.27 – 0.30 gallons per hour coasting in neutral.
Car was fully heated up, running about 30 minutes. Engine was at 185 F and Intake 68 F. Car consumed 0.24 – 0.25 gallons per hour coasting in neutral.

Here is the best test that I can think of to check that your car is functioning properly. Only takes an hour and costs about $10. Go to an interstate or highway where you can drive 60-70 mph. Fill up your car at a fuel pump until it clicks off 3 times. Drive for 30 minutes on the highway in one direction, turn around, and drive back. Try to be “nice” to the car, moderate acceleration using cruise control and going with the flow of traffic. Don’t hyper mile, just drive nice. Come back to the exact same fuel pump (important) and fill the car to the same level (clicks off three times). Compute your MPG. This won’t be extremely accurate, but should be close. Compare this number to the EPA highway rating on your car. If your MPG on this roughly hour highway only trip doesn’t meet or exceed the EPA highway figure, I would bet there is something wrong with your car.

[SmellyCat]

Is your idle to high? It should be 700-800.

Loosen the kick down cable on the trans, it should stay in high gear a little longer.

did you get car from a used car dealer, I've seen some real stupid rigging to make cars appear sellable. Maybe it would not idle and they set it real rich

does it have stock air filter setup or a hot rod cool air intake?


What rpm does it shift into 4th gear?

If you got muscles, take power steering belt off.

vacuum leaks will fake out sensors, fill a spray bottle with water, spray vac hoses, listen for engine stumble.

Make sure clamps on intake hoses are tight to throttle body, and its not cracked and air filter hosing is clamped good...SC

[pete c]

There is one solution to getting great mileage when all your trips are under 5 miles.

It's called a bicycle.

No vehicle out there will get good mileage when it is running in closed loop the majority of the time.

[AndrzejM]

Originally Posted by jayliu1984

What do you look for on spark plug and O2 sensor? There is no Check Engine Light, so beside to see if it is visually dirty, how do I know if they are affect anything?

This car is pretty new, 2009, do you think it is possible to have manifold leak and how do I even go about checking it?

You can check if o2 sensor is working properly with any OBDII scan tool or ScanGauge, UltraGauge etc. You should see Lambda numbers which should vary in a pretty fast rate. If the changes are slow or there are none your o2 sensor is just a piece of junk.
Regarding spark plugs you should check the gap between electrodes. It should be in a factory range.

I've seen leaks in almost or brand new cars either so the car age is not a factor here. Sometimes is just a bend hose, loosen screw or many other small things that can affect air fuel ratio.

You can do one more test. Let your engine to idle for a while just to warm up a bit and then just smell the exhaust gases. You shouldn't smell unburned fuel. If you feel that or you see any smoke like fumes there's something wrong. Then you should take your car to any service for exhaust gasses analysis. It can tell many many things of your car's engine to see what is coming out of the exhaust.