chadfo

I wouldn't wait for 100K to change spark plugs. I've changed mine at 30k, 60k, and 90k and the center electrode showed considerable wear. It would be all but gone if I'd waited for 100k.

I also don't think we get the best mileage at 3500 to 4000 RPM. The faster you go the lower the gas mileage. The closer I keep mine to 3000 the better mileage I get.

eburgsspeedyxb

you want to complain? I see no better than 20 MPG right now.

blown_xa

it's your Mass air flow sensor, get a new one

snowromance

what does the air flow sensor have to do with it? im curious. is it altering the fuel delivery from being bad or something?

blown_xa

yes, that and the o2 sensors are what tells the ECU how much fuel is delivered. Also, I know personally 2 people who had the same problem, and a new MAF solved it

hotbox05

30k spark plug change interval.

jwaj2002

my manual says not to change them till 100k, so do both local dealers

jaimecosio

i will say gas
the last time that i fill my car was in october i get 380 miles
3 days ago i fill up again and i just get 250 miles

hotbox05

in an xb my manual says 30k.

Robot_Box

wheres that? how much is one of those? and how hard is it to change?

hotbox05

it's right in your intake piping. it's expensive , very easy.

vintage42

Low tires could cost 1 mpg. Winter blend could cost 1 mpg. Short hops in frigid weather, with the engine constantly starting from cold and then running on a rich mix below its full operating temperature, will cost several mpg. Water in the injectors will make the engine miss and not run, but it takes a lot of water collected at the bottom of the tank to be picked up by the pump. Winter gas has drying agents (methanol, alcohol) to absorb the small amounts of water that may be caused by winter condensation, allowing it to be burned without affecting the engine's running.
The best mpg is acheived by using the least throttle and least rpms, and will occur by holding a steady 40 mph in 5th = 2000 rpm.
That cannot be sustained in travel for very long, but 55 mph and 2750 rpm can be, and on several trips I have gotten 42 mpg doing that.
It is also important to increase speed gradually, and to hold the throttle steady at speed. Most people know that acceleration from a stop takes extra gas, but fewer people realize that holding a steady speed by constant throttle corrections also takes extra gas. Holding 60 mph by constant small throttle changes can drastically drop the mpg. Every little push on the throttle is a mini-acceleration that wastes gas.
People who drive Interstate commutes often constantly use the throttle to jockey and maintain position in traffic, and although their speed may hover around 65 mph, they will not get the mid-30s mpg that steady cruising at 65 can produce.

Jan06xB

Check your tail pipe for soot - that will tell you if you are running rich from a bad O2 and or MAF sensor. Tires leak air all the time and require refilling. Change your tranny lube - the original stuff really has a lot of friction in it. Try a really slow light pedal acceleration in first gear and rev the engine to 5k and see if you have to keep giving it more gas to increase the RPM - if so then something in the engine is not adjusting i.e. valve timing or ignition timing issues or your oil is shot. Check tire wear and front end alignment and the front end bolts on the connecting struts holding the engine to the chassis and make sure nothing is loose or out of wack. Check for brake drag and brake dust on the front wheels. Lastly check for leaking fuel when the engine is running under the car and under the hood.

koalaty2

Factory spark plugs wear. Check the spark plug gap. I have been recording gas mileage for 30K now, and just changed the plugs. (I had noticed a drop of about 4 MPG recently over the last 5K. Gap of plugs were supposed to be somewhere within .028" to .031" from factory. When I removed the factory originals, they had worn to .036". No wonder the drop in mileage. I will probably check my new set at 10K. If I had checked the original ones at 10 or 15K, I could have just regaped them and not noticed the drop in mileage. I would suggest changing the plugs at 30K as factory recommends, but checking (and regaping as required each 10K, Even if I assume they started at .031 (highest recommended factory gag), then the plug wore .005" in 30K (or .0017 per 10K). So if your plugs start at .028" gap, (smallest recommended) in 20K they will be our of specs (.028+.0017+.0017) =.0314. And because the factory suggests starting at .028, that means that is actually the optimum gap for best operation. Check plugs at 10K (regap as required), change at 30K. Who says you can't teach an old dog new tricks.

TerribleTed

Plugs are cheap in my book. If I am going to the trouble to pull them out I am going to replace them ( be sure to regap new plugs, they often arent gapped where they should be). My routine is change plugs every 12-15K always. Seems to work over 30 years. Perhaps I waste a few dollars on plugs, but my cars have always run better after changing them.

metal112524

No matter how hard i drive my car of how much i baby it around i get a consistent 270 mp/tank on my box about 40/60 highway/city. this is with 10 gallon fill ups consistent everytime. I actually experimented driving like a winter texan and road ragin around and its the same back to back 27mpg. Now i took a trip to Oklahoma city and got 40mpg back an forth over about 3500 miles (i went other places too) so ya kinda weird.

koalaty2

Changing plugs that often (10-15K) would prevent them from getting out of tolerance, and I would definitely not argue much against it. And plugs are pretty cheap, unless you go with the Iridiums. The stock ones are cheap. The thing about the platinum or the iridiums, they are talking about the center electrode, and that is all. The ground electrode is not made or covered with these metals that last practically forever. Would not go over 30K, under any circumstance. At the very least, check at 10-15K, and change (or regap if you don't want to purchase new plugs), but still want the plug within stock tolerance.

redwar1441

if your intake has an oiled filter, like a k&n you could have oil on your maf sensor causing incorrect reading. Buy some throttle body cleaner and clean it out. Usually it will throw a code when this happens tho.
Tire pressure is a HUGE possibility so is winter gas.
Clean the maf, put the stock intake back on and air up your tires/oil change with synthetic and see what happenes.

Ford_Falcon

Well, I thought I'd give my xB a bit of tlc as well, but haven't had much luck on getting the mpg's back just yet. I used to remember early on in the life of owning my ride I would get 300 miles out of her before the fuel light would come on. Now I'm lucky to get 250. I've even been checking the fuel gauge whenever I drive, estimating I should get at least 75 miles out of her for every 1/4 tank fuel mark. Here's what I've done with my own tuning:

* changed spark plugs. NGK platinum, 0.44 gapped.
* took out the stock air filter, replaced with a BOMZ cold air intake.
* set tire pressure to 50 psi all around.
* changed oil. Mobil 1 synthetic.
* changed pcv
* cleaned MAF sensor (sprayed it with a little gum-out)

Unfortunately, no change in mpgs yet. If what blown_xa says is right, I may have to try the O2 sensor, and/or a replacement MAF sensor.

vintage42

Mileage is more dependent on how you drive than all the things you did. You drove easier when the car was new. And then and now, you have not done the long division to get your actual mileage numbers. The fuel gauge is not linear.