i need somebody help me out...i have a honda accord 98 lx 4 cilynders and he's spending too much gas...i changed the oxigine sensor already and nothing... :/ thanks in advance

 

Boy that was a descriptive post....

1) What MPG are you actually getting?
2) What gas are you putting in the car?
3) What maintenance items have you done?
4) What kind of tires/wheels do you have? And are they in good condition?
5) Are there any CEL's?
6) Is it an automatic or manual?
7) Why did you randomly change the O2 sensor?
8) Are there any leaking fluids?

I could go on, but hopefully you get the picture. Randomly changing the O2 sensor is not going to net you better gas mileage if you're sitting on 22's with a car that hasn't had an oil change in 5 years, is running low on coolant and you're putting in diesel fuel into it and not 87.

 

oh ok muffi,but when i conected the computer to the car it showed that the o2 sensor wasnt working right,thats why i changed it...the gas is normal,no regular, the wheels are in good condition,i changed the oil like a month ago, and it's an automatic car... so idk mister muffi :/

 

Well how much is too much gas?

When was the last time a tune up was done?

Air filter
Spark Plugs & wires
Distributor Cap & rotor
Timing belt & valve adjustment

 

Well you neglected to mention you had a CEL for the O2 sensor....

Fill up your tank all the way to the top, reset your trip meter, run it down to about 1/4 empty, fill it back up all the way.

Look at the trip meter and divide the miles there by the amount of gallons you fill up. That will give you your approximate MPG.

Just saying like "I only get 300 miles per tank" tells absolutely nothing about the actual MPG as the gas gauge can be inaccurate.

 

tune up it was like 2 month ago...

 

Ok, so that brings it back to the question of what kind of mpg the car is currently achieving?

 

FYI: Changing the air filter does not actually improve gas mileage. It's a myth that has been proven false. I found some articles on it online like 2 weeks ago. It does help with acceleration though.

 

^wrong^

Think of a car like a system of work in physics. You have the engine, which is the prime mover or the system and provides power to move the vehicle. However not all of the energy generated by the combustion of fuel is used to power the wheels. Some of it is lost to the accessories, electrical system, air conditioning, power steering. Some of the energy is dissipated through the cooling system as heat. Some is lost due to driveline losses. (friction, gearing, rolling resistance etc.)

Finally there are pumping losses. A "pumping loss" is energy that the engine uses to move air in and out of the cylinders. Now, a vehicle needs C amount of energy to the wheels in order to move at 60 miles an hour. However the engine, tasked with overcoming all of the energy losses present "L" and still put "C" energy down to the wheels.

Now the engine must produce X energy in order to do that.

So the engine must produce enough energy (X) to satisfy the requirements of "L" and "C"

X must = C+L in order to maintain 60 MPH.

However what happens when you reduce the energy requirement of L by changing the restricted air filter, and putting in a new filter that does not require as much force to move air through?

When you reduce the energy loss through pumping all of that extra energy must go somewhere, because energy is always conserved. That energy goes into the wheels of the car, moving it faster that 60 MPH.

So how do you stay at 60 MPH? Well, if you reduce the engines total energy output, until the system is once again in euqilibrium, you can maintain 60 mph, with the engine producing less energy. How do you get an engine to produce less energy? Burn less fuel, which translates into better gas mileage.

The entire goal of tuning an engine is to make it more efficient. Where the end result differs between economy and speed, is that speed turns that efficiency into more power for the same amount of fuel. Economy turns it into less fuel for the same amount of power.

 

Ya I agree with all that but I still think that's more of a performance geared argument then anything else. I read about pumping losses when I googled this before. But, this is how I was thinking about it. Say your throttle is 50% open (percentage open doesn't really matter for this argument). Even with a clogged filter, you'll eventually have the right amount of air flow to the engine. Between the MAP sensor, o2 sensor, TPS, etc the ECU is going to match the correct amount of fuel for the amount of air coming in. Even if the filter is clogged, it's still going to get the right amount of air/fuel which accompanied by spark will give your car the exact power it needs to go.

Quick google search found me this.
http://www.garagejournal.com/forum/s...ad.php?t=65665

 

wow im talking with HERO!! with people who know about it! i really appreciate it and i will figure out what can i do!

 

I agree that the ECU will adjust AFRs according to what it receives for signals. It will always try to keep the 14.7:1 AFRs in check. However, if you want to maintain 60 mph you will require more throttle with a dirty filter than you would with a clean filter. More throttle even at 14.7:1 AFR still = more fuel.

You have to compare how much fuel it requires to maintain a constant speed. Not how much vacuum is created vs air to fuel ratio. Of course the computer is going to scale the fuel down to match the lower air flow there is. That PDF is out of whack. I didn't read then entire thing but under their test setup information. They show that they are only testing differentials in intake pressure vs air fuel ratio. They even state that there was significant performance drop, but no effect on fuel economy. Maybe not at WOT like they were testing. How about setting cruise control at 50 and having a car try to maintain that with a dirty filter. Try and tell me that the lack of performance won't effect fuel economy in that scenario.

I may be wrong and all that mumbo jumbo is right. However I just cleaned my air filter and I can hear and feel the difference in my engine with the cruise control on. It doesn't accelerate half as much as it did with the dirty filter, therefore my MPG will increase as it always does.

 

How can we help you, You still haven't given us enough information about your car burning rich... you jsut said that it's spending too much gas. i'm not even sure what that means, sorry.

What kind of fuel economy (MPG) are you getting?

 

i put the tank full and it just run 200 miles! :/ no matter where i go!

 

and i put a new air filter..

 

Did you not read my post?

THIS IS NOT AN ACCURATE MPG MEASUREMENT AND DOES NOT TELL YOU WHAT MPG YOU ARE GETTING.

Use your trip meter and reset when you fill up your tank. Drive around until 1/4 of your gas is left then fill it back up all the way and record how many gallons you put in. Look at your trip meter and divide it by the gallons.

MILES / GALLON

So if you drive 300 miles and fill up 10 gallons you get 300/10 = 30MPG

 

And the reason if that comes off as rude - is no one can help you if you do not state what kind of mileage you're actually getting , 25mpg for example really is not terrible if that's what you have for city driving. Your gas gauge can be inaccurate and leading you to think you have half a gallon left when you really have 5 gallons left.

 

i did it already the tank is fuel, but i've to wait until the gas runs out to let you know!...But one month ago i filled up and it took 13 gallons and i ran 300 miles...after that i filled up againg twice and it just ran 200 miles :/ thats the point that i dont understand boss! its 4 cilynder you know, it no suppost to spend so many gas

 

Ok there's an answer more along the lines of what we were looking for.

What kind of driving are you doing to achieve this? Mostly city, mostly highway, mixed?

This could be a factor in the type of mileage you get. I personally get around 28 mpg during mixed driving in my 98 Accord LX with 225,000 miles (Around 400 miles on 14 gallons). Just as a reference.

 

It took 13 gallons every time or are you guesstimating?

 

You'll have to excuse me lol. Sometimes I forgot that AFR is JUST a ratio and does not determine how much air or fuel is actually being used. So you got me lol.

 

Thank you muffinman, sorry if I didn't explain that part so clearly. But its about energy, it take more energy from the engine to pull air through a dirty filter than a clean one.

That energy is created by burning more fuel. Clean filter, don't need the extra energy, don't need the extra fuel.

I was explaining it in terms of energy.

What is your driving style like? It may be a relatively small 4cyl, but if you drive like a maniac hitting 6k off every stoplight you aren't gonna see good mileage.

Honestly, if 13 gallons to 300 miles is what your averaging, 23 mpg isn't crazy off, that EPA est mileage for that car is 19-22 city and 27-28 highway off the EPA site. Now that's not what you are going to get. But it's not wildly suspicious either.

 

it's in the city and yes it takes 13 gallon...

 

Then you aren't very far off of what would be "in spec."

Something to consider, is it an automatic? The manual allows for much better control over your mpg (compared to that sub-par auto at least, more high-tec autos can get close).

I get around 24-25 mpg (with a manual) in a pure city environment IF I drive what would be considered "normal."

Not all 4 cylinder cars are created equal in the mpg game. You can't expect "high" city mpg in a 3000 pound sedan. Something smaller like a Civic or a Fit sure, but they have their lighter weight (among other factors) to help them out.

 

could someone help me out?? im trying to change the gasoline filter for 1998 honda accord lx automatic,but i cant find it!