2003 ZTS - horrible gas mileage - 16.3mpg - HELP

[whynotthinkwhynot]

For anyone else concerned with fuel degradation, call your congressman and suggest that we mobilize the ethanol industry for conversion to isobutanol that reduces emissions better than ethanol and doesn't degrade fuel or fuel systems.

[PWGuy]

Originally Posted by whynotthinkwhynot

It seems like you have the best advice so far. As long as the engine is running smoothly, there should be no other problems.

1) Correct your mileage calculation- use the method BCZX3 suggested.
2) The ECU reset shouldn't be done without doing the A/F reset at the same time. This requires you to idle the engine in P or N for 5 minutes after it is dropped out of high idle mode. When the test is finished, the idle will drop slightly. With her short driving- it might not have reset the A/F yet. I'd go out and start the car and let it idle for 7 mins exactly- TIMED. You can use the electronic odometer trick to see if the idle drops slightly after 6 mins or so. That will indicate it's done. I'd expect idle to be around 1100 for a car that has not passed this test, and 800 (IIRC) for an AT in N. It might be lower, but that is not bad unless the idle is extremely low in gear- like 500.
3) I didn't see mileage, or engine. We've gathered it's an AT, but we need to know the engine. Mileage is important also because if you're approaching 130k+ or so, and the timing belt has not been replaced, that would explain some of the issues.

Honestly, with a 2.9 mile drive, I'd only expect about 21-23 mpg, and yes, as Iminhell suggested, you might be experiencing fuel degradation. If nothing else, I'd give some Sta-Bil a shot- make sure you get the gas type not diesel. Finally- your fuel filter is due for a change. Yes I know, way under the 20k mark, but I do recommend that as 20-30k or 1 year. I change the wife's yearly, she puts about 10k per year on the van. It will be dirty.

1) Will put this into practice asap
2) I reset the ECU and waited 12 minutes. It idled at 1100 until a number of minutes passed, then dropped to 800 as you described. By all accounts, I've done it correct, right?
3) It is an auto with 130k miles and yes it needs TB/WP maintenance
4) I'm not expecting more than 21-23mpg, honestly. I'll give Sta-Bil a shot for gasoline engines. Also, I changed the fuel filter last year with a brand new Motorcraft unit - the car was barely driven 5,000 miles since then! (Winter car and now a short daily drive commuter). Are you serious that I need to change it yet again??? If so, maybe I should seafoam FIRST. Thoughts?

[whynotthinkwhynot]

Yep, I do change my wife's filter yearly. She does about twice that in mileage. Filter manufacturer doesn't really matter much when it comes to fuel filters. When you let the gasoline age like that it begins to separate and make all sorts of groovy stuff that sticks in the filters.

You can probably get away with waiting until after the winter if you want. I said yearly, you said November '11 of last year, so it's not quite a year. I'm not sure if your situation is worse than ours but I do know that 90% of the people out there on the road never change fuel filters. LOL We do get about halfway to the filter life in miles.

[VEGAS]

Of course its a Automatic, his wife drives it :D j/k

I think its the wheel bearings getting old, they drag a bit more and with our automatics its another loss.. Automatics loose efficiency compared to the manuals when they get around 100k miles.. , yes I own both a manual and auto and I see a HUGE difference. You should be getting mid 20s even when car is not running optimal.. I would remove the tires, check for drag on spindals.

I have gotten in to the habit of popping into neutral when I slow down... lowers RPM of engine faster then leaving it in gear and car seems to stop JUST a touch faster, also less drag at a stop on motor.. I see 2 or 3 mpg difference.

[sailor]

Plenty of good advice already, especially BC's & Whynot's comments.

All I can add is that "warming it up" before driving will REDUCE the MPG, not improve it!

And that I've seen a typical 5 mpg drop in mileage from winter tires instead of high mpg summer tires alone, e.g. - a vehicle that was consistent at 30 mpg summer went to 25 mpg with winter tires with no changes in driving BEFORE the weather got colder & winter fuel was involved.

Tires & 2.9 mile drives will give these results, my Focus that gets about 28/29 in "mixed" driving has gotten as low as 18 in strictly local driving (short trips only) and that was on summer tires... Same car will get high 30's on the road (highway only).

Do all the maint. required for the best results possible of course, but it seems like you're just dealing with a "worst case scenario" of real world driving....

An OLD hint for cars subject to this type of use is to take it out for longer trips as often as possible, the proverbial Sunday Drive is actually good for it! Lets it get warm enough, long enough to clean out some of the condensation & other crud that doesn't get a chance to evaporate in daily use, and even 'burns out the carbon" a bit. Modern engines with electronic fuel injection aren't as bad in this regard as old carbureted cars in this regard, but it still helps....

Luck!

[PWGuy]

Originally Posted by sailor

Plenty of good advice already, especially BC's & Whynot's comments.

All I can add is that "warming it up" before driving will REDUCE the MPG, not improve it!

And that I've seen a typical 5 mpg drop in mileage from winter tires instead of high mpg summer tires alone, e.g. - a vehicle that was consistent at 30 mpg summer went to 25 mpg with winter tires with no changes in driving BEFORE the weather got colder & winter fuel was involved.

Tires & 2.9 mile drives will give these results, my Focus that gets about 28/29 in "mixed" driving has gotten as low as 18 in strictly local driving (short trips only) and that was on summer tires... Same car will get high 30's on the road (highway only).

Do all the maint. required for the best results possible of course, but it seems like you're just dealing with a "worst case scenario" of real world driving....

An OLD hint for cars subject to this type of use is to take it out for longer trips as often as possible, the proverbial Sunday Drive is actually good for it! Lets it get warm enough, long enough to clean out some of the condensation & other crud that doesn't get a chance to evaporate in daily use, and even 'burns out the carbon" a bit. Modern engines with electronic fuel injection aren't as bad in this regard as old carbureted cars in this regard, but it still helps....

Luck!

Good to know about the winter tires - I had no idea they would negatively affect MPG by that much.

However, my tires are inflated to 40 psi..

[1hotfocus]

Originally Posted by whynotthinkwhynot

It seems like you have the best advice so far. As long as the engine is running smoothly, there should be no other problems.

1) Correct your mileage calculation- use the method BCZX3 suggested.
2) The ECU reset shouldn't be done without doing the A/F reset at the same time. This requires you to idle the engine in P or N for 5 minutes after it is dropped out of high idle mode. When the test is finished, the idle will drop slightly. With her short driving- it might not have reset the A/F yet. I'd go out and start the car and let it idle for 7 mins exactly- TIMED. You can use the electronic odometer trick to see if the idle drops slightly after 6 mins or so. That will indicate it's done. I'd expect idle to be around 1100 for a car that has not passed this test, and 800 (IIRC) for an AT in N. It might be lower, but that is not bad unless the idle is extremely low in gear- like 500.
3) I didn't see mileage, or engine. We've gathered it's an AT, but we need to know the engine. Mileage is important also because if you're approaching 130k+ or so, and the timing belt has not been replaced, that would explain some of the issues.

Honestly, with a 2.9 mile drive, I'd only expect about 21-23 mpg, and yes, as Iminhell suggested, you might be experiencing fuel degradation. If nothing else, I'd give some Sta-Bil a shot- make sure you get the gas type not diesel. Finally- your fuel filter is due for a change. Yes I know, way under the 20k mark, but I do recommend that as 20-30k or 1 year. I change the wife's yearly, she puts about 10k per year on the van. It will be dirty.

Just tried the a/f reset, after a minute or so idle is at 800, after 7 minutes idles around 690-710

Sent from my SAMSUNG-SGH-I717 using FF Mobile

[PWGuy]

Originally Posted by VEGAS

Of course its a Automatic, his wife drives it :D j/k

I think its the wheel bearings getting old, they drag a bit more and with our automatics its another loss.. Automatics loose efficiency compared to the manuals when they get around 100k miles.. , yes I own both a manual and auto and I see a HUGE difference. You should be getting mid 20s even when car is not running optimal.. I would remove the tires, check for drag on spindals.

I have gotten in to the habit of popping into neutral when I slow down... lowers RPM of engine faster then leaving it in gear and car seems to stop JUST a touch faster, also less drag at a stop on motor.. I see 2 or 3 mpg difference.

I will remove the tires and check for drag on the spindals. I assume I just jack up one side and spin the tire to see if any dragging, similar to brake drag or caliper sticking? And I assume I do this for all four sides, correct?

Overall, you are right, we should be getting AT A MINIMUM low 20s in MPG.

[VEGAS]

Each spindle must be checked and tires should be removed to see if it feels overly stiff. It wont spin free, but will have a SLIGHT drag, However sometimes this to wont tell the whole story, sometimes just replacing them with OEM is the only way to know.

[IH84DZ]

I see a lot of variables in here that don't make your mileage figures a shocker. Unless you are calculating fuel economy by filling your tank, logging mileage and filling the tank at the same pump again while dividing the miles driven by gallons used - your fuel usage figures are terribly inaccurate. This may sound unacceptable given you are using the fuel gauge but if you understood how a fuel gauge worked it would make more sense. They are accurate estimations of fuel level, not accurate measurents of fuel level.

A drive of less than 3 miles (especially in cool temps) is likely not enough time for the engine to reach closed loop. In open loop it fuels the engine based on a programmed table that is certainly rich of stoich and thus it will consume more fuel in open loop than it will in closed loop. This is aside from all the other problems you can expect with such a short run cycle.

Your tire compound will negatively affect fuel economy as well because they have more drag compared to a street tire - regardless of how much air you put in them

It is a good idea to check for dragging brakes - especially if you've had brake issues in the past

How much extra weight is in the car?

What is the ethanol content of the fuel being used?

Your woman may have poor driving habits. I can make a motorcycle get 10mpg if I try hard enough........

Get rid of the K&N filter. MAF based Fords are notorious for aftermarket filters (especially "performance" filters that use oil to trap FOD) messing with the air turbulence across the MAF sensor and/or contaminating the sensor with oil. Comparing what mileage you get with a go-fast air filter to what others get with paper filters isn't a very valid comparison.