Bone Stock 93 LX 121k odom, BAD Gas MPG??

[smac]

Hello cb7's,

I am only getting like 300 miles to a full tank? I am very mechanically incline and perform all mods and maintenance on all my vehicles currently. I just changed the oil 12/31/13 and the Transmission fluid 10/13. The car runs perfect. First crank with no gas given (after letting FP prime) and no rough idles, shifts smooth etc. The only thing I really noticed that was off was I checked tire pressure the other day and all tires were at about 25-26 psi. I couldn't even really tell they were low is why they were that way. I inflated them all to 32psi now and am monitoring the gas mpg now that fresh oil and tranny fluid are in and I just filled up. Anyone have any ideas of what to check next?

Again, car is completely stock other than short ram intake with K&N air filter.

Taking all suggestions. Thanks in advance for your help.

smac

[kratemertyl]

Having bad oxygen sensors and air filters can reduce your gas mileage by up to 20%. The oxygen sensors help keep the proper mixture of air and fuel, and having this off balance can be inefficient.

Your spark plugs are responsible for sparking combustion in your engine. If they misfire, or are working poorly, this can effect your gas mileage in a negative way.

Having bad fuel injectors can cause bad mileage. This is because the fuel injectors are responsible for putting fuel into the engine. If there is a leak of some sort, then less fuel will make it to the engine, and then in turn make it run less efficiently.

Having your air conditioner on causes a lot of gas to be wasted in powering the system.
A common cause of bad mileage is your own driving habits. If you are an aggressive driver, likely you accelerate to quickly.

The type of motor oil that you are using can also affect your gas mileage up to 12%. You want to use motor oils that are high in reducing friction. Either use a synthetic oil or the oil that the car's manual recommends.

The more revolutions per minute you make your engine do, the more gas you will use. so drive slower. Driving the speed limit of 55 miles per hour is much more fuel efficient than driving at 60, 65, 70, etc miles per hour

I work in the oil and gas industry so im all for people burning it up, but i do like to save where i can as i know fellow cb ers do too.

[Accord problems]

around 300 miles to a tank of gas is normal for the cb7 . some get a little more because the simple fact is they are running leaner . running leaner is not good as you use less gas you also run hotter and the risk of going boom. now if you run richer then you use more fuel and this depends how rich can cause a failed engine or faster ware on certain part's . my advice you're car ain't broke so don't fix it .

[smac]

around 300 miles to a tank of gas is normal for the cb7 . some get a little more because the simple fact is they are running leaner . running leaner is not good as you use less gas you also run hotter and the risk of going boom. now if you run richer then you use more fuel and this depends how rich can cause a failed engine or faster ware on certain part's . my advice you're car ain't broke so don't fix it .

Just doesnt seem right? Our tanks are 15-17 gal capacity (depending on who or where you search) If you take 300 divided by 15 your at 20mpg. I read all the time where folks are stating they get like 30+ out of their cb7? How is this? I am going to do a tune up soon and hope it increases but am not wanting to believe any "Honda" unless somethings broke getting only 20mpg....

FYI: For easy math 450 on a full tank at 15 gal cap is 30mpg.....

smac

[Accord problems]

20 year old car = 20 year old trip meter . if you can fined a way to rebuild it or replace that trip meter with a bran new one ( not used ) then you will know you're true mileage . with these trip meters they are off after 20 years . i know mine is and every honda i seen around here the trip meter stopped working at 10 to 15 years old . how ours still count is beyond me . but they are not right for the most part . and like dude stated you probably ain't getting a full benefit of you're tank do to a old gauge / floater .

[MrMagnificent]

I recommend buying a afr gauge and sensor kit, you can easily snag one up for $200.

Your going to buy one anyways right?

The Wideband 02 is a must have if you will eventually look into chipping and tuning.


Check what the gauge says first, before you start spending money on parts beyond what you already would for routine maintenance.

Good luck.

[turboHLS30]

I get 21mpg out of mine with no O2 sensor in right now. The most I've gotten out of a full tank (15 gal.) is 320, and the least was 274. Mine is a '93 EX auto wagon with intake, header, and exhaust.

[Fleetw00d]

You have to stop talking about miles per tank and start actually calculating the fuel mileage. The specs may say 17 gallons for tank capacity, but that it not all usable. Other threads (and my personal experience) indicate that an empty tank (as in running out of fuel) results in a fill up of approximately 15.5 gallons. Also from experience, the low fuel light comes on at different levels for each car; some may come on as early as being only 12 gallons down, others as many as 14. The mileage will vary significanly with what type of driving you're doing. My wagon may only get about 20 mpg for the short trips my daughter makes around Galveston, but will get 30 for purely highway driving.

Keep a log of how many miles you actually drive and how many gallons of fuel you actually use. Divide the actual miles (for example 121,625 when you fill up minus 121,310 the previous time you filled up, that is 315 miles) by the actual amount of fuel you put in to fill the tank (for example, 13.5 gallons) to yield 315/13.5 = 23.3 mpg. When you have some real numbers, we can help you more.

[Accord problems]

also didn't the 5 speed's get better mileage than the auto's ?

[turboHLS30]

fleetw00d, that's how I calculate my mileage. I reset my trip meter everytime I fill up

[cb7 calling]

You have to stop talking about miles per tank and start actually calculating the fuel mileage. The specs may say 17 gallons for tank capacity, but that it not all usable. Other threads (and my personal experience) indicate that an empty tank (as in running out of fuel) results in a fill up of approximately 15.5 gallons. Also from experience, the low fuel light comes on at different levels for each car; some may come on as early as being only 12 gallons down, others as many as 14. The mileage will vary significanly with what type of driving you're doing. My wagon may only get about 20 mpg for the short trips my daughter makes around Galveston, but will get 30 for purely highway driving.

Keep a log of how many miles you actually drive and how many gallons of fuel you actually use. Divide the actual miles (for example 121,625 when you fill up minus 121,310 the previous time you filled up, that is 315 miles) by the actual amount of fuel you put in to fill the tank (for example, 13.5 gallons) to yield 315/13.5 = 23.3 mpg. When you have some real numbers, we can help you more.

Yup. I have rolled into the station gas light on many times and never have filled up with more than 14 gallons and some change. I usually get 400-440 miles a fill up and check it every fill up, again I go till the gas light is on often(I don't recommend that). You have to check your miles and gallons per fill up then do the math. It sounds to me like your car is fine. 300 miles is usually around or a little below quarter tank for me. That's likely when you fill up. I get 30-31 mpgs. It's a five speed.

[deevergote]

Anything below 25mpg can be a sign of a problem.
Do a full tuneup... plugs, cap, rotor, wires if they're not in good shape. Set your ignition timing and base idle.

Make sure you aren't carrying excessive weight. I noticed a drastic decrease in MPG when I was carrying around equipment for my band.


If your check engine light is on, that would definitely be a reason for a problem. I assume you'd have mentioned that... but just in case it's on, read the code and fix the problem.
A bad or failing oxygen sensor (only one, not multiple as implied above) can be a cause for poor MPG without throwing a CEL code right away. A new Denso sensor is fairly cheap on Rockauto.com. Might be worth replacing.

[Fleetw00d]

fleetw00d, that's how I calculate my mileage. I reset my trip meter everytime I fill up

When I said "you", I didn't necessarily mean you (turboHLS30) in particular, but those who say they get so many miles per tank. I keep a log in Excel for each of my vehicles, then plot the mileage (instantaneous, averaged over six fill ups, and total since I bought the vehicle). I can't help it, I'm an engineer. Chart below is an old one for the coupe I wrecked last year. Keep in mind all the things that will affect the mileage for any particular tank of gas: driving type (city or highway), style, variability in pump shut off, different blends of fuel, etc. Most of the high peaks represent a long highway trip, mostly round trips from Cincinnati to Pensacola, FL. Most of the rest of it is mixed highway/city.