Poor gas mileage '02 Explorer 4.6l V8

New to the forum so please bare with me. I am getting poor mileage on my 2002 Explorer Limited V8. 6-7 mpg. I know this is really off the charts poor mileage so I'm reaching out for help. The car runs fine and shifts smooth. Has 69000 miles Had the car for just over 2 years now. No check engine light and no hesitation. I had the rear end rebuilt about a year ago by Ford cause there was a knock noise when I accelerated but now fixed. I changed the plugs with oem platinum Motorcraft plugs and 2 months ago 1 coil went bad and replaced with a Motorcraft coil. I am always up to date with my maintenance on the car. Only performance mods done to the car are K&N intake system and Borla dual exhaust cat back system. Any advise would be greatly appreciated..Thanks

Welcome to the forum!

The K&N intake system is a good hint, you may have a contaminated Mass Air Flow (MAF) sensor. If you've ever cleaned and re-oiled the K&N, then I'd just about guarantee that a dirty MAF is contributing to the concern.

The oil has a tendency to coat the sensor elements of the MAF and cause the engine to run a bit rich. If you have an Advance Auto Parts nearby, go there and pick up a can of CRC MAF Sensor Cleaner along with the security Torx bit to pull the MAF. Unplug the MAF, remove it from the air intake tube and clean according to the directions on the aerosol can of MAF cleaner.

The MAF was likely transferred from the stock air intake duct to the new K&N intake system in case you're not sure what it is.

If that makes no difference, then consider replacing your coolant temperature sensor.

-Rod

Thanks for the repy Rod...
I just did the maf cleaning today. Pulled the maf out removing the two torque screws holding it in place and sprayed it down with CRC electric cleaner. Put it back in the car and she started right up. I guess it will take a few days of driving to see if there is a difference. You mentioed that I should change the coolant temperature sensor if the maf cleaning doesn't work. Would that cause the poor mileage? Where is the coolant temperature sensor located? Thanks again.

Yesterday there was a post on the Taurus forum where someone had fuel economy issues. They cleaned the MAF with electric parts cleaner and it didn't fix it. They then bought a can of the MAF cleaner and that doubled their fuel economy. I've used electric parts cleaner with the MAF in the past with good results, but something to keep in mind. http://www.automotiveforums.com/vbulletin/showthread.php?t=685579&page=2

The coolant temperature sensor contributes to how rich or lean the PCM adjusts the air/fuel ratio based on measured engine temperature. If this sensor is out of specification, it could be causing the PCM to make the ratio quite rich. The sensor is usually located near the thermostat. You need to be alert though, usually there are two sensors that look nearly identical and are often in very close proximity to one another. One is the sending unit, the other is the sensor. The sending unit is for the guage, the sensor is for the PCM. You want the sensor in this case.

-Rod

Thanks so much for this helpful info. I think I'm gonna go ahead and change the senor as well. Hope it doesn't cost much. The MAF really didn't look all to dirty when I removed it. Wouldn't the check engine light come on if the sensor was bad? I only had the light come on 1 time when a coil went bad. I would have thought that with such poor mileage that the check engine light would have come on or the engine would be idling funny but no such symptoms. I'll let you know what happens after the new sensor is installed. thanks again

Any one have any idea where the coolant temp sensor is on the v8 2002 explorer? I know its usually right next to the thermostat housing but there's nothing there.

From the factory service manual for the 2002 Explorer:

Engine Coolant Temperature (ECT) Sensor — 4.6L

Removal and Installation

1. Disconnect the battery ground cable. For additional information, refer to «Section 414-01».

2. Drain the cooling system. For additional information, refer to «Section 303-03».

3. Remove the generator. For additional information, refer to «Section 414-02».

4. Disconnect the ECT sensor electrical connector.

5. Remove the ECT sensor.

6. To install, reverse the removal procedure.

-Rod

joe, have you had this poor mpg since you bought it, or after one of the modifications, maintenace?

For the most part it has been like that scince I got it and just recently got slightly worse. I had my local shop hook it up to their computer and they said it was running fine. No codes. Even got my new inspection last week. I am now getting 1 mpg better scince I cleaned the MAF sensor. Still getting poor MPG's though. Just can't figure this one out. And now that gas is skyrocketting I don't turn her on unless i absolutly have to.

A couple more questions: Have you replaced the coolant temperature sensor, and are you gauging fuel economy by the trip computer or via actual calculations when you fill up the tank?

Also, make sure that the previous owner didn't install one of those cheesy "performance chip" resistors in place of the Intake Air Temperature (IAT) sensor. The IAT should be located in the air filter housing, or very nearby there.

-Rod