I have been trying to figure out why my 2000 dodge durango 4x4 with a 5.9L had a loss of power and really bad gas mileage since 40,000 miles. Below are the things I did but never fixed the problem.

Intake, Exhaust, new plugs, new rotor and cap, new msd ignition wire, throttle position sensor, O2 sensor, etc.

After years of trying to figure out and trying everything in the book on how to improve fuel economy. I just about gave up.

Well, I had an issue with another dodge car where the map sensor went out completely. So, I gave it a shot on the durango as well. So, what does the map sensor do? It tells the computer how much pressure is in the manifold. Thus, telling how much fuel to pump in. Take a look at your throttle body, it will build carbon over time. The map sensor has a diaphram inside of the sensor, so over time carbon build up and the diaphram hardening up will not cause the sensor to fail but rather read inaccuratly.

After I replaced the map sensor:
Power return to like a new car condition
My gas mileage returned
Runs like a new car again
Engine no longer knocks

Those of you with poor gas mileage issues that have replaced everything else, may want to give this a try to get their gas mileage back.

I remember When I first started trying to figure this out, people with the 5.2L also had this problem.

To give you an idea about gas mileage, I was getting 13-15 mpg on the highway with the old map sensor at around 70mph. Now with the new one at cruising I get 18-22 mpg on the instant mpg monitor.

Huge jump in mpg. With gas prices the way they are, your map sensor will pay for itself in no time.

 

You posted in the wrong forum. A 2000 year truck would be a 2nd gen. I will transfer this post over there.

 

Well hot damn.

 

Cheapest place to get your map sensor will be either autozone or pepboys. Around $60-$70.

 

damn that would be nice if that would work on my truck 5.2 auto and gets about 10-13mpg heck if I could get 16 I would be happy.

 

might need to look into that, if the 5.9 is getting 20+ imagine what the 4.7 can do...

 

When my 5.9L was new, I would get 17-18 mpg. Overtime, after about 40k miles my mileage went to crap. If, your mileage hasn't gotten drastically worse, why change it.

I thought the 4.7L had a maf sensor?

 

whats the difference in a map or a maf? i'm

 

MAP =Manifold Absolute Pressure (which is what Chrysler uses, this includes the 3.7/4.7L)
MAF = Mass Air Flow

Basically, the MAP reads the intake manifold pressure (or, vacuum), and sends that to the computer, which in turn adjusts injector pulse rate and spark timing.

The MAF, as I understand, basically heats a wire that runs in the air intake tube (between air filter and throttle body), to keep the wire at a constant temperature. The computer, from reading the voltage requirement to keep the wire at the pre-set temperature, can "figure out" how much air is entering the engine to make the same changes as mentioned above.
MAF sounds a little over-complicated to me. My Corolla has MAF sensor. My friend, who also has a Corolla, told me he read people were having problems with their MAF because on the aftermarket air filters people use (the kind you have to clean with oil, like K&N), the oil fouls the MAF sensor.

 

map sensor (manifold absolute pressure sensor) = measures your manifold pressure, this allows the ecm to work with the O2 sensor to come up with the correct air/fuel ratio. In simple terms, the ecm knows how much fuel to pump into the cylinders.

maf sensor (mass air flow sensor) = This sensor is usually before the throttle body (between the air box and throttle body). It measures the amount of actual air going into the engine. The MAF & O2 sends the voltages back and allows the ecm to calculate the correct fuel to dump into the engine. The only way a Maf can read faulty is if you are using a k&n filter and the oil is all over the maf sensor's resistors.