Gas Mileage Question?

[grubby21]

Will vacuum leaks decrease your gas mileage? I understand that the pcv valve has a horrible reputation about leaking. so i am just going to start buying and replacing all the sensors (MAF, IAC) and such. and of course the pcv. just wondering if these things affect fuel mileage.

 

[yavapaires]

Will vacuum leaks decrease your gas mileage? I understand that the pcv valve has a horrible reputation about leaking. so i am just going to start buying and replacing all the sensors (MAF, IAC) and such. and of course the pcv. just wondering if these things affect fuel mileage.

Why would you replace all those sensors? Yes a vacuum leak could cause fuel mileage issues. What kind of mileage are you getting? My 96 4.0 OHV, automatic, Control Track with 149,000 miles gets right around 20 mpg. Thats at 5000 feet elevation.

 

[corkey]

if there are no codes than the sensors are good, waste of money putting all new in,,

 

[koda2000]

all of the electrical sensors on your engine effect fuel mileage. they are there to inform your vehicles computer of existing conditions so that the computer can make whatever changes necessary to maximize efficiency for the purposes of fuel mileage and emissions. and yes, a vacuum leak can effect fuel mileage.

all that being said, changing all your vehicles sensors for no specific reason is a waste of money. Some wear out over time (O2 sensors, TPS) and need to be replaced. others (MAF, IAC) need to be cleaned periodically. you're vehicles sensors are designed to operate within a specific voltage range. when your computer detects a sensor not functioning, or functioning outside of its designed range, it turns on the check engine light (CEL) and sets a code. the code can be read with a scanner, but that’s just the starting point in figuring out what the real problem is. for example, a vacuum leak will may throw a code of a lean condition. if you suspect your PCV valve's hoses are cracked and leaking causing a vacuum leak, inspect and replace the hoses as necessary, not just the valve. sometimes multiple codes are set because of a single problem. track down and fix the correct problem and the other codes go away. A loose fuel cap often sets a vacuum leak code, but simply tightening it fixes the problem. another good example is if you have 160k and have never changed your O2 sensors, that would be a good place to spend some money and it should improve fuel milage.

 

[LONO100]

try to remedy problems that might be tripping the sensors before you replace the sensors. they are tripping and sending messages and codes for a reason. once you have exhausted all other options, then try feplacing the sensor. fix vacum leaks first!

 

[archlab]

Agreed about the Vacuum Leaks - I just changed out 2 of the 90degree rubber hoses which go along the passenger side of the engine twds the front & have noticed that my mpg seems to be doing a bit better. It's a good idea to check these to see if they have collapsed over time. In my case, they did at about 190,000miles (2001 S/Trac).

Also, I pulled off the sensor going into the throttle body & cleaned it (I haven'te spent much time working on this vehicle, so I'm a bit rusty on the 'architecture', but I beleive that's the IAF that I cleaned).

One thing that happened to my 1992 Navajo many years ago, was that the main air intake had a crack & was fouling up the metering of air (plus mpg, plus chk eng lt & rough idle).

Overall, these engines are pretty easy to diagnose & service...until you need to do something simple like change a valve cover gasket (another way to complicate work so that you feel compelled to turn this over to the Dealer). Aside from my usual gripes abt 'Designed-In Failure Points', the Explorer Platform is pretty well-done or a low/mid-level vehicle.