Getting 12.5 miles per gallon gas mileage :( how do i get it back?

[layinthesmack31]

Hey guys

Well i know it is winter time and all and that i use more fuel in the winter cause the heater is on alot but i am only getting 12.5 miles per gallon of gas. That seems like it is really low haha. I dont even know where to begin to find out how to get the gas mileage back. i have replaced the spark plugs, new thermostat, ran techron fuel injector cleaner through it, new air filter, and the only check engine code i have is 332 and i cleaned the intake out and also replaced the dpfe sensor. i just dont know what is going on. i get about 150 miles until it gets to the 1/4 mark left in the tank. and i dont even get on it hardly ever. i try to keep the secondaries from kicking in because if they kick in the gas really goes down. I thought it was eating gas because the thermostat was bad and the car would never heat up any farther than the A on NORMAL on the temp gauge. it is usually around the L but sometimes makes its way to the A then i hear the fan kick on and it cools down. I guess that is all the info i have for now so any input would be greatly appreciated. thanks

Matt

 

[40BelowSummer]

ATX?

how warm does it get according to the water temperature gauge?

 

[seraphiem]

Well the first question people will ask is if you have performed a 60k. IE, the things that directly influence your mileage;

Condition of O2 Sensors, ECT, TPS, Intake Air Temp, Thermostat, throwing any codes, vaccum leaks, and finally valve clearances.

Things that sometimes go unnoticed but could cause a HUGE loss of efficiency;

Sticky brakes - Usually stuck rear caliper pins, or collapsed rear brake lines.
Clogged Cats
Wheel Bearings and your tires themselves.

I'd check the easy things first, like O2s and your back brakes. Clogged cats is extremely common as well.

Just for reference when I first picked up my SHO I was getting 7 mpg. After completely restoring everything on it I ended up with 17 mpg if I'm really conservative. More like 14~15 when I stand on it from time to time.

 

[40BelowSummer]

Excuse my ignorance, how do valve clearances directly influence your gas mileage?

Also when I got my ATX SHO it got 14mpg mixed city/highway, after my 60K (O2's and ECT were the contributors) I got 31.4MPG on a straight shot highway trip

 

[Blank-Disk]

hear any strange noises in the engien durring idle? I'm currently chasing a cam chain problem. Take a screw driver and put it on each fuel injector, and put your ear to it each time, if they all sound synchronized, then do the same thing on vital parts of teh engine, like the timing belt, cam chains, valve cover bolts and so on.

 

[seraphiem]

I'll be honest I don't really understand or comprehend why out-of-whack clearances would cause a shift in mileage. I always thought having a really tight or loose valve would start to affect engie efficiency and hence mileage. IE, the engine is designed to run around a particular valve clearance and any deviance will impact it.

Doing the valves (usually every 6k miles!) on all my bikes over the years has always resulted in ever so slightly better mileage. Since then its always been stuck in my head.

My biggest factors were the O2 sensors and the rear brakes. After replacing the stock O2 sensors I went from the low of 7~8 mpg to about 12~13. Completely rebuilding the entire back brake system resulted in the increase to about 17.

Replacing the other things such as the ECT, TPS, and IAT had no affect on my mileage.

 

[sdpatt]

If you are using the VENT or FLOOR (or OFF) settings on your ECC then you are not causing the A/C compressor to engage. All other settings will use the compressor and apply an additional load to the engine, reducing efficiency. The heater in itself is just warm engine coolant being circulated through the heater core and air being diverted through it. The "heater" does not add any additional load to the engine.

The 332 code can be caused by plugging of the EGR passage with exhaust and crankcase contaminants. The blockage is usually at the lower pair of "nostrils" in the split of the intake just inside from the throttle body. This can be inspected and cleaned without even removing the TB. Just remove the intake hose at the TB and open the throttle plate with the cam. With a light shining on the split, can you pass a coat hanger with a 90 degree bend on the end through the lower nostrils? Clean with same coat hanger and a little intake cleaner solvent.

The O2 sensors should be replaced with the spark plugs every 60,000 miles. They get old and slow and reduce power and efficiency even without setting a code.

As long as the temperature gauge stays within the NORMAL range, then it is... normal. The coolant temperature must exceed approximately 168F (approx. the bottom tick mark on the NORMAL scale) to get the engine control system into closed loop mode. That is when the full assortment of sensors is used to keep the fuel mixture at the best for power, efficiency and minimum emissions output. If the gauge stays below the "L" then the t-stat may not be fully closing - its normal mode of failure.

 

[layinthesmack31]

Well i have replaced the O2 sensors as well but i forgot to mention that. I have also replaced the TPS. The only thing i know of on the brake issue is that i did have to replaced a locked rear caliper about 6 months ago and now it seems like i get a funny noise from the rear but it quits when i hit the brakes so i was told that it isnt the wheel bearing and no one seems to know what the noise is. it is kinda like a high pitched squeelly grinding noise haha one time this summer i realized that there was smoke coming from the drivers side rear caliper but that was the only time i notced it. i didnt know that the rear brakes could cause gas mileage drop. i inspected the pads and rotors on the rear and they seem to be fine. but now that u mention it i notcied the noise in the middle of the summer and now that i think about it it seems like the gas mileage went down a little then but maybe now it has just got worse. The bad thing is when i take it to a shop and they drive it they dont hear the noise since it doesnt occur all the time. I just dont know what to do. This car is about to be driven off a bridge soon because i cant afford the all the damn gas i have to put in it haha. i have not done a 60K since i have had it and i have had it for 2 yrs but only put about 10,000 miles on it. I would like to do it myself because the shop quote was quite expensive i just dont know how yet and i would like to try it some weekend when it warms up around here. Well any more infor would be greatly appreciated. thanks

Matt

 

[jruss1601]

I just got my waterpump replaced along with the thermostat and the timing belt. Before i was getting an average of 18 mpg, no higher than 22. Now, i've only filled up twice, but i got a 26 and a 23. Something in there was the problem. My brother was mentioning that an out of whack timing belt could affect mpg.

 

[SeanMc]

I get 14-15 on the street, and then 26-ish on the highway. Are you modded in any way?

 

[NJSHO]

I was going to say stuck caliper or bad wheel bearing. Could try cleaning the Maf elements with MAF cleaner. Im not sure how much an effect this might have, but have you checked the vacuum hose to the fuel pressure regulator?

 

[dantheman68]

i have a similar problem... i drive like a grandma and still only get 15MPG... im replacing my cats and ECT with my upper 60k this spring.

 

[platoribs]

In the original thread it was mentioned that he changed the rear caliper. While that might have addressed some caliper problem, the more likely problem is when the rubber flexible rear brake hose becomes restricted internally. The force from the master cylinder will get past the restriction but it doesn't let it off after you remove your foot from the pedal.

If you are going to do any brake work on the back end of a Taurus you should change the brake line also.

 

[zak]

Drive the car on the highway for several miles, try to coast down into a rest stop or a safe offramp/parking lot, using brakes as little as possible. Get out and feel all four wheels near their centers, especially comparing both rear brakes. Sometimes the rear brake line can collapse and keep light pressure on the brakes, caliper pin worn, etc. Have not been very impressed with the aftermarket caliper guide pins for the rear of these cars (93-99) they allow too much misalignment (on the other hand the Ford ones can sieze). Also verify that your torque converter is locking up when cruising in third and forth.

Was the thermostat a Ford or an aftermarket one? If the later, you need the proper Ford one.

zak

 

[93rev2sev]

In the original thread it was mentioned that he changed the rear caliper. While that might have addressed some caliper problem, the more likely problem is when the rubber flexible rear brake hose becomes restricted internally. The force from the master cylinder will get past the restriction but it doesn't let it off after you remove your foot from the pedal.

If you are going to do any brake work on the back end of a Taurus you should change the brake line also.

Bingo! Feel your wheels after a 20 minute drive....be careful...if the calipers are sticking you WILL BE BURNED

 

[itwonder]

You've gotten some good advice. The rear caliper issue is most likely a brake hose issue, same happened on my car. I would:

1. Replace all rubber brake lines, front and rear.
2. Disassemble and clean rear brake load compensating valve assembly
3. Adjust load compensating valve actuator lever so it is pressing down on valves as hard as adjustment range will allow.
4. Make sure parking brake is not dragging.
5. Replace ECT
6. Make sure thermostat is proper Ford one with specified temperature and installed in proper orientation. (Do a search).
7. Verify wiring from ECT to computer.
8. Check exhaust system for obstructions.
9. Check air inlet system in LF wheel well for obstructions.

 

[Devin]

I would also run premium gas if you aren't since the car recommends it. You can get worse gas mileage if your car is detonating prematurely.

I did a "refresh" on my car, where I changed almost every sensor, seal and gasket, the water pump and alternator, wheel bearings and brakes. I just filled up 6 gallons after drivin 160 miles which comes to about 26MPG. Last time I was getting about 24MPG. You should be able to get that at some point as well, so don't give up.

 

[Mad Celt]

Did you do wires with your plugs? Sounds like every SHO I've seen that needed wired.

 

[SHO_DOODmorrris]

i think your brake line is collapsed like a few have said. im in the middle of a brake job and i had a calipr replaced by ford 2 years ago on the passenger side and i just removed both rear calipers and realised that the passenger side one is sticking and its not a stickey e brake. try that 20 min test drive out and see how it works.

-M

 

[Lightning]

wow, 18 responses and not one person said proper tire pressure (I know, seraphiem mentioned tires, but not what to do with them... ).

How about clean air filter, correct wheel alignment, excess weight (eg: tool kit in the trunk, 150 pounds of garbage in the back seat...), drag on the car (roof racks, luggage racks, huge 3 tier ricer spoiler)???


Make sure the basics are right first, then dig deeper...



Oh, and any drivability issues? Stumbles, lack of power, etc? You changed plugs, how about plug wires?






Hey cool, this feels like pin the tail on the Donkey, could be almost anything. =\