Getting bad gas mileage

Good morning,

There are so many factors for fuel mileage.

Driving habits are the most important.

Tires. The tires need to be properly inflated and check regularly.

Alignment. Front end alignment is critical for the car rolling free.

Brakes. Make sure they are not hanging up. Have them checked regularly.

Filters. Make sure the air and fuel filters are changed every year.

Transmission. Make sure the shift points have not changed.

Roy

i have had this car about eleven years. every thing is changed always at time, but now it has bad mileage, new spark plugs coils is installed, filters. only code sometimes show is p0705.no check engine overdrive light. car drives good but getting bad mileage. tires are balanced, alignment is done. i saw that longft and srift is always in negative, car sometimes idle.
shrift1 (%) -0.8
longft1(%) -10.9
shrift2(%) -3.1
longft2(%) -8.6

The long terms could be from either the engine running a little rich, possibly from an air filter, or the sensors are worn out.

the 705 is for the transmission range sensor not reading correctly. That would have nothing to do with the mileage issue.

Timing chains are the other thought. Have you ever had them replaced?

Roy

No, never. which sensor may be worn out?

Oxygen sensors.

The timing chain controls valve timing. If the chains are worn, that timing will change and you will get less mileage.

Roy

if timing chains are bad it should have sound? engine working fine no bad sounds

no, not at all. They slack off and you cannot hear that at all.

Roy

thank for answer. how can i check if chain went bad?

You would need to do a compression test and compare the readings to new.

https://www.2carpros.com/articles/how-to-test-engine-compression

Then the cover for the chains should be removed to inspect. That is a big job and if you are going to go that far, then you might as well replace it.

Roy

Our compression test was done about three month ago mechanic sad that compression was good (like new one).

Okay, that was three3 months ago and this is now and you have different mileage.

Roy

mileage from the test changed with 200 miles, i will check that again.

Okay, sounds like a plan.

Roy

I have seen MAF cause this problem even though the numbers are kind of where they should be the sensor shows less air than what is entering the engine. I would replace it will new. here is a guide and diagrams below:

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

installed new maf sensor, also compression test was done "perfect numbers"
now showing
Shrift1 (%) -7.8
longft1(%) -13.3
shrift2(%) -7.8
longft2(%) -8.6
maybe air leack ? car drives good

The long term trims indicate it is running rich. They should be much closer to 0.

Have you had the injectors professionally cleaned? Additives have no effect on cleaning.

Roy

Update:
injectors professionally cleaned, new air intake gaskets,car runs better. now showing this :
Shrift1 (%) -2.8
longft1(%) -5.5
shrift2(%) -3.4
longft2(%) -5.5

Much better.

Is the light off now?

Roy

check engine light was off, better gas mileage now . next week i will try smoke test.

Sounds good.

Roy

Update: no air leaks car drives good
cold start
Shrift1 (%) -2.8
longft1(%) -5.5
shrift2(%) -3.4
longft2(%) -5.5
but when worms up
Shrift1 (%) -3.8
longft1(%) -8.5
shrift2(%) -4.4
longft2(%) -8.5

Also what is RPMDSD (Desired Idle Speed) for Ford Escape 2003 3.0? Mine shows 745-780 is it normal? Aand also when i turned of IAC sensor car was running much better about 650-700 (but some times was misfiring) getting better gas mileage now.

Got it.

Okay, you need to adjust the base idle to 500 RPM. There is a base idle screw on the throttle body and after setting the idle to 500, plug in the IAC and the idle should return to normal.

Roy

Can you show photo where is that screw?

Okay, I cannot see the screw in any drawing. You need to look where the accelerator cable attaches to the throttle body. It will be there.

Roy

update car runs smooth
shrift1 (%) _0.8
longft1(%) _ 0
shrift2(%) -_0.8
longft2(%) -0
MAX
shrift1 (%) 7.8
longft1(%) -0
shrift2(%) -5.5
longft2(%) -0
getting 26 highway
19 city

Is the check engine light on or off?

Roy

Is the check engine light on or off

Roy

Check engine light was off all time. getting better fuel mileage than last three years.

Good deal.

Roy

Hello, update:
shrift1 (%) 28
longft1(%) 2.3
shrift2(%) 32
longft2(%) 2.3
car runs bad. :/ only thing that i changed today is vacuum break booster (bought from junk yard) it's can be bad vacuum break booster ? car was running good when i changed vacuum break booster than car was running bad and rpm are high.

Junk yard parts are never a good idea.

Yes, it sounds like it is bad. I would get a rebuilt one.

Roy