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Fuel Economy
MORE: Fuel economy questions
Getting the most from your gas? - It is no secret gas
prices are up and putting a big pinch on our pocket books.
Car maintenance
and driving habits significantly affect fuel economy. Here are a few tips
to help you get the most for your buck. First, check the air pressure in your
car's tires. Most vehicle tire pressure recommendations are located on a sticker
in the driver's door jam or on the side wall of the tire. While tire and car
manufacturers recommend a prescribed tire pressure, it has been shown that slightly
more tire pressure is optimal for achieving higher fuel economy by reducing rolling
resistance. Some hybrid cars are manufactured with tires that can hold up
to 55 P.S.I. as compared with the usual 32 P.S.I. For safety and better gas mileage
always keep your tires
properly inflated. Next, analyze your driving habits. Do you take off quickly from
a stop? Try easing into the throttle and allow the vehicle to accelerate slowly.
Observe the traffic and signals in front of you. If a stop is imminent release the
gas pedal and allow the car to coast the remainder of the distance before using
the brakes.
Proper maintenance of your car's engine is essential for optimum performance. If
your
engine is misfiring it will decrease mileage. If the
engine oil
and filter changes have been neglected it will cause additional friction inside
the engine and
hinder the
performance
and gas mileage. Finally, remove all un-necessary objects from the car, added
weight can decease mileage also inspect your engine service records and perform
a tune up or oil change as recommended. Following these gas saving tips can increase
your mileage and save you money.
Car Fuel Economy Questions and Answers - This category contains featured
questions as examples. They relate to most vehicles.Question: 1999 Ford
Taurus LX Wagon mileage 90,000 . I am a fellow licensed mechanic, up here in Alberta.
This car was given to me with blown head gaskets. I replaced them and new head bolts,
all plugs, wires, serpentine belt, put in new Synthetic oil like previous owner
had since new. It does not use a drop of oil and runs like a charm. It had the engine
service light on when I first restarted it, probably from antifreeze on the O2 sensor.
Replaced them and light went out. The previous owner claimed it only got 20 MPG
since new. I have driven it through 3 tanks of gas now, and he is right. The last
tank had a new air filter in it but no difference. It has lots of power. I believe
this car would beat my 68 Mustang with a 302 auto in a race. What do I look for
to fix this mileage problem? It has no Codes at all and I changed everything except
the fuel filter as the previous owner changed it a month ago.
Answer: Depending upon the type of driving that you do, twenty miles per
gallon (MPG) may not be too bad. Check with other owners of similar cars and see
what kind of mileage they are getting. If the twenty MPG is low, check the Mass
Air Flow Sensor .
Question: 1999 Lincoln Mk VIII mileage: 128,000. I have just had the transmission
rebuilt in this car and now I have developed two problems that did not exist prior
to the rebuild. The first is that I get an intermittent "check engine" light. This
comes on usually after 3 minutes and goes off and on with no pattern as to engine/speed.
The second is that my gas mileage has gone from 22-24 mpg avg. to 16.5 or less.
The error codes and the computer have been reset but the light keeps coming on and
the mileage is horrible. The shop replaced one of my oxygen sensors at their expense
believing they had somehow damaged it during the rebuild. My transmission shifts
as if new and there seems to be no problem with the rebuild. The engine is running
smoothly and has plenty of power and all normal startup computer checks read OK.
Any thoughts on where to look/things to try would be helpful.
Answer: We think you have a Mass Air Flow Sensor that is out of range
and needs to be replaced.
Question: 2001 Ford Focus, miles : 79,000. My wife contends
that operating the vehicle at low Rpms, almost to the point of lugging, results
in better fuel economy. I have been under the impression that the smaller vehicles
were to be driven at the higher RPM's to maintain performance and minimize long
term maintenance problems, (sludge, plugged injectors, etc.). Can you help us with
this impasse?
Answer: Lugging an engine at low speeds is not particularly good for an
engine. On the other hand, high RPM can cause accelerated wear. The key here is
moderation with regular maintenance as recommended by the manufacturer.
Question: 2004 Honda Accord. Does running your A/C reduce your gas mileage?
Answer: Yes it does. The air-conditioning system uses horsepower from
the engine to run the air conditioning compressor.
Question: 1999 Nissan Altima mileage: 134,000. Since March of this year,
I am keeping records of my car's mpg averages. I began to notice a significant drop
in fuel economy. In the city, the averages were between 22 and 24 mpg, and in the
highway, the average was 26 without reaching 27. All this with new aftermarket spark
plugs, wheel alignment in all four wheels, correct cold air pressure (32 psi front,
29 psi rear), new set of spark plug cables, a nearly new distributor cap and rotor,
and an rpm adjust made at a local dealer. I was using an oil that wasn't energy
conserving, 15w 50 synthetic, the one I was using since the car was new, and I decided
to use 10w 30 synthetic, so fuel economy improves, and it remained the same. Here
in Puerto Rico, heat is a problem and that is why many mechanics including dealers,
use oils that aren't energy conserving. But, well, even with the 10w 30 oil, the
problem was there. I read on the Internet, that the oxygen sensor is related to
fuel efficiency and that the best sensors are usually replaced at 100,000 miles.
So I decided to replace the oxygen sensor with an equal aftermarket oxygen sensor,
the same one my car had since new. And, the result was good.
The highway mileage improved, but not exactly to the 34-35 mpg average, I obtained
in the past. I obtained 31.4 mpg controlling the speed, the acceleration, and the
braking in a long trip. The problem is that I still obtain between 22.5 and less
than 24 mpg in the city, using the car under the same roads I used it when it was
new. This car is capable of delivering 26-27 mpg under these conditions because
I calculated its fuel efficiency when it was new. Some people around me say that
this is not a big problem, due to the fact that the engine has nearly 134,000 miles
and there is wear, even after using synthetic oil since the car was new. Also, this
car is automatic not standard. In spite of this, the fact is that I am running at
least 20 miles less with each and every fuel tank, having all of the above checked,
and this happens consistently. This means more fuel expense, and I think that probably
something can be done to put the fuel efficiency of this 1993 Nissan Sentra (automatic)
closer to where it is suppose to be, which is 26 mpg in the city and 35 mpg in the
highway.
I did something that two different local Nissan dealers did not, which was replacing
the oxygen sensor for an exactly new oxygen sensor and it worked, so that was part
of the problem. But, the car is still below its average. One more thing is that
this car had its accelerator cable adjusted by a local mechanic, not a dealer. Can
this affect its rpm? Sometimes, after driving and for example, stopping at a parking
lot, the car seems to remain at a higher rpm than usual, instead of reaching a lower
rpm level. This happens, but not all the time, maybe 50 percent of the time. Other
thing is that in the mornings when the car is cold, I heard a sound similar to the
one you can hear on a blender immediately after start up, and it disappears quickly,
happening only when the car is cold. In the past, the car made a similar sound and
the starter was replaced, but somehow, this sound is different. The catalyst hasn't
been replaced, is running with the same one it has since new. The other thing, are
well. The car runs and accelerates well, but the accelerator feels hard when I compared
with the past. This is since the accelerator was adjusted, what mechanics here call
the accelerator leg, and other call it the accelerator cable. I don't know if that
adjustment is making a difference, but I am going to try with other spark plugs
I have, to see if there is a difference with the ones my car is using right now.
Since I am using these spark plugs, I haven't heard the usual engine knock that
this car makes in heavy traffic, using premium fuel all the time. And, because the
owner's manual relates the small amount of engine knock with fuel efficiency, maybe
that is another fact.
Also, I don't know about the rest of the sensors this car uses, (if they are
working well), but I do know that there are many other sensors or parts related.
(I have the big manual also). I don't know about the new gasoline's that are being
sold, but here in Puerto Rico everybody uses premium 93 fuel all the time. Well,
that is all the information I have. Maybe others have bigger problems, but one of
the virtues of this car is its fuel efficiency, and if it looses it, the car looses
a great part of its value. This is not a Porsche, or a BMW M3, or one of the other
monsters around, but is a reliable car, that requires little maintenance, and, it
usually delivers better fuel than the average by far, which I read that for 1999
the mpg average was 23.8. Pablo in Puerto Rico
Answer: First, we would replace your aftermarket spark plugs with the
same brand that was original equipment from the factory. There is a good chance
that your catalytic converter is partially plugged if it has not been changed in
134,000 miles. If the timing belt has been replaced, verify that the cam timing
is correct. We have worked on cars brought into us with complaints similar to yours
and found that the timing belt had been installed one notch off. Rather than correcting
the problem some mechanics take a short cut and adjust the distributor to compensate
for the incorrect belt timing. This works, but mileage is compromised. Finally,
do a compression and leak-down test to find out the condition of your engine.
Question: 2002 Ford Thunderbird mileage: 71,000. Hi guys. I have a gas
consumption problem with this car that I have had since I purchased it a year ago
with 55,000 miles on it. I only get 200 miles out of a tank of gas. It has an 18-gallon
tank. This is involving mostly expressway driving, very little city. I average around
14 mpg, which is abysmal. Taken it to several Ford dealerships, which test and say
according to their diagnostic computer, I should be getting 26.7 mpg. The car runs
perfectly, except for an occasional shudder coming from the transmission. There
are no gas leaks at all. The dealerships don't know what's wrong with the car, so
I am hoping you can steer me in the right direction.
Answer: Try replacing the Mass Air Flow Sensor and the fuel filter.
Question: 2003 Ford Pickup F-150 mileage: 70,000. My truck has two
gas tanks. Front tank is slightly larger than the back. Noticed a drop in
fuel economy lately (past few months). Started checking, front tank gets the
usual 17-mpg. Back tank varies from 11 to 13. No fuel leaks (at least
not when it is sitting in garage). No fuel smell. Runs good. Any
suggestions? I checked your previously answered questions but didn't
see anything quite the same. Thank you for your time!
Answer: Your problem with the fuel monitoring system, check the oxygen
sensors and the mass air flow sensor.
Question: 2001 Nissan Fronteer 2WD mileage: 67,000. Help me Bob
and Ken! I am having a TERRIBLE gas mileage problem. In the last 8 months,
my fuel economy has dropped from 16 mpg to 12 mpg! I have spent over $600
having the problem diagnosed to no avail. Repairs that were made include Adjust
throttle linkage, Scoped and set engine, throttle body gasket repair, timing adjusted,
tune-up, new plugs, new O2 sensor, new catalytic converter, vacuum lines tested,
emissions tested, and exhaust system check and fuel injector cleaning. After
putting the truck on 2 different diagnostic computers, at 2 different places, 2
different mechanics have stated the engine was in great shape to have so many miles.
I know that with so many miles that I'm not going to get the same gas mileage as
I did when I bought it (24 mpg), BUT 12 MPG IS CRAZY! Please see what you
guys can come up with.
Answer: Several things should be checked; fuel pressure regulator and
mass air flow sensor. If you have not had the computer scanned, you should
do it now having all five modes checked.
Question: 1999 Z28 Camaro mileage: 84,000. Hi, I have a Z28
Camaro. When I first bought the car a few years ago, I was getting great mileage
(20-25) gal. My car has a carburetor, but has all of that emission equipment
for California. I recently changed the o� sensor, set the timing, and adjusted
the carburetor, so I was wondering what happened to my mileage (10 miles per gallon
now). So please answer my question, and give me some info on the computer
controlled q-jets.
Answer: Your car is equipped with a computer controlled engine
management system. An independent auto service center can scan your computer
for fault or error codes. The information should pinpoint the malfunctioning
components. The mileage problem you are having may indicate you are ready for major
tune up.
Question: 2002 Dodge Grand Caravan mileage: 60,000. On a resent
long trip, I experienced poor fuel mileage. Before the trip I did a tune-up,
new plugs, wires, air filter, PVC etc. Once we started, I noticed that we
were getting about 23 MPG but after 20 miles, the mileage would drop to 12 to 14.
When the engine was cold after stopping for lunch or dinner the mileage would start
at 23 then again drop to 12-14 after 20 miles. I notice the tail pipe was
black. Doing a key on engine light test, I found the following codes.
1-2, 5-1, 5-5. This said the O� sensor (replaced at 82K) was detecting a lean
mixture. After coming home, I took the vehicle to my local repair shop where
they could not find any codes stored. The car is still getting poor mileage.
It must be a sensor, where should I start? Thanks, Ben
Answer: You may have a faulty oxygen sensor or coolant temperature
sensor.
Question: 1996 Pontiac Bonneville mileage: 167,000. In the past
month and a half, my mileage has gone from 450 miles per whole tank to 300-330 per
whole tank. I believe it is a 15-16 gallon tank. At first, I thought
it was due to colder weather when I started getting about 50 miles less per tank.
But now (mid December) I am suddenly getting 100-130 less per tank. What can
I check for and what are some possible problems that might be causing this?
Thanks!
Answer: If a major tune-up has not been done recently, this
could be the cause of your problem. Replace the spark plugs, plug wires, fuel
and air filters, etc. Also, replace the oxygen sensor. In addition,
service the fuel injection system. Clean the carbon deposits from the throttle
bore and idle passages. Check the catalytic converter to make sure it
is not plugged or restricted.
Question: 1999 Dodge Neon mileage: 115,000. 5 speed. Had this engine
rebuilt at 100,000 miles about 5 years ago. This spring, the mileage dropped
from 18-20 mpg around town to 10 mpg. New 0� sensor last spring. Computer/ECU
2 years ago. New coolant temp sensor this summer. Why the drop in mileage?
Answer: Several things should be checked; fuel pressure
regulator and mass air flow sensor.
Question: 1999 Chevrolet 1500, miles: 145,000 I have replaced plugs,
alternator, belts, changed oil, cleaned injection, and replaced fuel sensor, and
my car is consuming too much gas. It uses almost 3/4 of a tank of gas to drive
50 miles. How can I repair my car so it doesn't use so much gas?
Answer: Check fuel pump and Mass Air Flow Sensor.
Question: 2001 Plymouth Neon mileage: 85,000. Gas mileage has suddenly
dropped from 250 to 125 or so per tank. Some power loss when pull off from
a stop but other than that runs well. Dealership mechanic says it checks
out OK. Sounds OK.
Answer: Check the catalytic converter to make sure it is not “plugged”
or restricted. Your car is equipped with a computer controlled engine management
system. An independent auto service center can scan your computer for fault
or error codes. The information should pinpoint the malfunctioning components.
Question: 1997 Jeep Wrangler, miles: 78,200 That gets between
18-20 miles per gallon. Is there any way to improve the mileage?
Answer: Your Jeep is equipped with a computer controlled engine
management system. The fuel mixture is constantly monitored and adjusted for optimum
mileage and performance. The only way to improve mileage is change driving habits
i.e., slow starts, constant speeds etc. Keeping your Jeep in top running condition
also helps.
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