low gas milage question

dwitczak · #1 11-09-2006, 07:18 PM

I just bought a 99 taurus wagon with DOHC, it has 108k miles. I am getting about 14 miles to the gallon. Very low. But, i do not know if it is related, but the emergency brake is very hard to engage. Do you think it might be partially applied, while driving? It seems to run very well, but we just got the car.

Any thoughts?

shorod · #2 11-09-2006, 09:29 PM

Does the car seem to coast well? Jack the rear wheels off the ground and properly support the car with jackstands. Try to rotate the wheels. If they spin freely and don't stop as soon as you stop applying rotating motion, the parking brake is probably not the main cause of the low fuel economy.

How cold is it in PA currently? Does the car start and run fine after sitting overnight, or is it a bit hesitant to stay running if you put it in gear immediately after starting it on a cold morning? If it doesn't seem like it wants to stay running, you may have stuck secondary butterflies.

If the car runs fine cold and fine all the other times, then check the air filter. If the air filter is an oiled type, then I would almost put money on your Mass Air Flow (MAF) sensor being dirty and causing the low fuel economy. You can remove the MAF sensor and spray it off with electrical parts cleaner (available at many auto parts stores). Be careful when cleaning it though, the sensor elements are quite fragile.

If the air filter is not an oiled type and is not dirty, then you may want to investigate your coolant temperature sensor. If the sensor is out of range, it could be telling the PCM that your engine is at a different operating temperature than it actually is, and cause the PCM to richen the air/fuel ratio. There is usually one sensor for the PCM and a different sender for the temperature guage, so just because the guage reads normal doesn't mean the PCM is getting good temperature data.

For good measure, add a bottle of fuel injector cleaner to the fuel tank as well. A $2 bottle of injector cleaner can fix some pretty amazing driveability issues!

-Rod

fotbalcrazy2 · #3 11-10-2006, 01:17 PM

I have a 97 taurus and I feel that the gas mileage is going down too. I have an K&N filter and have "recharged" it. It uses an oily substance. Would that be the cause of a dirty MAF too?

MyTaurus8AChevy · #4 11-10-2006, 08:08 PM

Quote:

Originally Posted by shorod

You can remove the MAF sensor and spray it off with electrical parts cleaner (available at many auto parts stores). Be careful when cleaning it though, the sensor elements are quite fragile.

How does this remove?

We've also heard many others talking about how fragile the little wires are. They say to NEVER touch them with your hands.

MyTaurus8AChevy · #5 11-10-2006, 08:14 PM

Quote:

Originally Posted by fotbalcrazy2

Would that be the cause of a dirty MAF too?

Only if you OVER charged it. Otherwise it should be fine. We have a K&N and we get great gas mileage, although it's probably not just from that one thing that we've done.

shorod · #6 11-10-2006, 10:03 PM

Yes, the oil from an oiled filter can coat the sensor elements of the MAF and lead to poor fuel economy, but as MyTaurus8AChevy suggested, this is typically only if the filter has been over-oiled (which I was guilty of once myself).

The MAF sensor can be removed from the air intake housing by unplugging the connector, then removing the 4 Security Torx screws from the sensor. The MAF is located between the air filter housing and the throttle body in the air intake tube. It is usually quite close to the air filter housing. The connector will usually have 3 or 4 wires in it. Once the screws are removed, you will need to rock the sensor a bit to get the o-ring seal loosened up.

I usually will carefully clean the elements with a very small swab. I'm young and still pretty steady though, with good eyes. They are fragile and one small bump or startle and the sensor will be junk. Start by just spraying the elements with a good electrical parts cleaner. The elements are usually shrouded in such a way you don't have to worry about touching them with your fingers.

-Rod

MyTaurus8AChevy · #7 11-10-2006, 10:11 PM

Quote:

Originally Posted by shorod

The MAF sensor can be removed from the air intake housing by unplugging the connector, then removing the 4 Security Torx screws from the sensor.

Do they all have the Torx screws? I didn't see any screws on ours

shorod · #8 11-11-2006, 11:05 AM

What year is your Taurus? The sensor itself is usually mounted to the MAF housing with 4 Torx screws. The housing is typically installed in the air intake with a couple of hose clamps, or it will be mounted to the plastic air filter housing.

-Rod

MyTaurus8AChevy · #9 11-11-2006, 12:30 PM

Quote:

Originally Posted by shorod

What year is your Taurus?

2004. There is a plug a few inches away from the MAFS that has two torx screws holding it on. I took some pictures and I'll be able to post them later today for you to see. It says MAFS right next to what I'm talking about but now I'm thinking that the actual sensor might be the plug a few inches away.

MyTaurus8AChevy · #10 11-11-2006, 07:01 PM

shorod · #11 11-12-2006, 09:16 AM

You are correct, the one in the right of the image appears to be the MAF sensor. "MAFS" in the rubber hose is to designate where that end of the hose goes (instead of to the filter or throttle body).

Your MAF does appear different from what I'm used to seeing. It's unclear to me from the photo if your sensor is installed with Torx bits or something else.

-Rod

MyTaurus8AChevy · #12 11-12-2006, 10:21 AM

Quote:

Originally Posted by shorod

It's unclear to me from the photo if your sensor is installed with Torx bits or something else.

The one on the left (green one) does not have any torx screws holding it on. You have to do something to that green clip, but after studying it for a while I still can't figure out how it comes off

The one on the right with the torx screws I removed yesterday. It had what appeared to be very small diodes or resistors used to take readings when the air passed over them. I did spray cleaner on them and reinstalled, but my main concern was cleaning the one on the right (the green one). I'll try to take more pictures of the green one and post them. Maybe it will jog someones memory on how it comes off. If anyone knows how this one is removed PLEASE let us know

shorod · #13 11-12-2006, 11:36 AM

Are there wires going to the one on the left? If so, how many? If there are only 2 wires, I suspect it is the Intake Air Temperature sensor, a thermistor. There's really not much to clean on it, if it is the IAT sensor.

I suspect you press on the green button, then pull the connector loose from the device.

-Rod

MyTaurus8AChevy · #14 11-12-2006, 12:00 PM

Quote:

Originally Posted by shorod

Are there wires going to the one on the left?

Now that you mention it there are no wires going to it

So it can't be the MAFS, even though it says it is. Still would like to take it out and clean it.

Quote:

I suspect you press on the green button

Nothing to press. It 'almost' looks like you turn it, but it doesn't seem to want to turn. Here are two closer views of it.

shorod · #15 11-12-2006, 05:48 PM

The "MAFS" on the hose is just to designate that as the end of the intake hose that connects to the MAF sensor (MAFS). It's unfortunate they molded the letters into the hose so close to the other part. I suspect that suspect part is part of the emissions system and will probably show up on your emissions label.

-Rod

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