I have a 92 Ford Explorer and i have changed the plugs and wires and i changed the air filter and the O2 sensor..... and im still getting bad gas mileage i get about 10 miles per gallon is this normal for a 4x4 Explorer.... Any help would be appreciated... thanks

 

That's pretty bad mileage, even for an Explorer. Things I would do:
1) Run the EEC-IV self-tests, just in case the computer sees a fault. See www.dalidesign.com/hbook/eectest.html for instructions. Note that, if you don't have a voltmeter/test light, the codes are also output to the CEL when STI is jumpered to STO. Be sure to follow the other instructions carefully, false codes can be triggered by running the tests on a cold engine, or by neglecting steps.
2) Check the fuel pressure. Also check the vacuum line to the fuel pressure regulator (FPR) for gasoline after the engine has been run. Gas in line = bad FPR.
3) What temperature is the engine running at? I used to get worse gas mileage simply from a bad thermostat that didn't allow the engine to warm up completely.
There's a start for you.

 

I checked the codes with the engine running and i keep getting a code 172 and a code 53 and a code 83..... and with just the key on im getting a code 173....

 

Interesting. Let's work these out.
1st question: Did it pass the KOEO test? In other words, did you get a pass code (111) from the first set of codes output during the KOEO test?
2nd: Double check your KOER codes. A false 172 is easily set by running the test without running the engine long enough to heat up the O2 sensor. As for the 53 and 83, a '92 computer should output 3 digit codes instead of 2 digit codes. Could this have been a 538? A 538 would be a pretty common code, indicating that you missed the "goose" test.
3rd I'm assuming the 173 is a continuous memory (CM) code. If you don't know how to distinguish between a KOEO and CM code, then review the instructions. It offers an interesting contradiction to the 172 KOER code (if the 172 is a real code). 172 indicates lean, where the 173 indicates rich. Don't worry too much about this 173 until you determine if that 172 KOER code is real.

 

hey sorry about that i miss read that about getting the codes...... when i run the test with the engine runing it goes into the high idle mode for a min and then it goes down to about almost 1,000 rpm and then it runs the self test..... it first blinks the 111 codes and then it blinks once then i get a quick pulse but i still cant figure out where i need to move the throttle for the goose code.... i get a code 538 which is system did not recieve goose test.... and then i get a code 536 which is...... Brake On Off open or shorted to ground and i still get the code 173 which is Oxygen sensor not switching - system is or was rich - Single, Right or Rear HO2S..... thanks

 

Let's review the instructions for the KOER test. Here's how interpret your description of the test:
this is the engine id that is output at the beginning of the test. Three pulses to signify a six cylinder engine (4 cylinder would have 2 pulses, 8 cylinder would have 4 pulses) Press the brake at this point to activate the BOO switch. This is the cue to perform the "goose" test. When you see this pulse, quickly apply and release the throttle. Try to get 3/4 to full throttle. this would be the "fast codes" no information to be obtained here.

Now we're getting a 173 KOER. This indicates that the O2 sensor is always indicating a rich mixture. The question now is -- is this a real rich condition the computer can't compensate for, or is the O2 sensor circuit falsely indicating rich. O2 sensor codes can be difficult, but we have an advantage in that we have a KOER code, which suggests that the fault is constant rather than intermittant. Next thing I would check is fuel delivery. Start by simply checking for gas in the vacuum line to the fuel pressure regulator (gas=bad FPR). Then check the fuel pressure.

 

i have a 91 ex with 170,000 km my gas milage sucked and still isnt the best. the previous owner was very hard on it. ( a friend of mine ) he is a major led foot, and he lived on a nice big hill. At about 160,000 ( after finding all the other antifreeze leaks ) I came to the conclusion that my head gaskets were leaking. so I changed the head gaskets and had the heads redone.
lo and behold the engine didnts sound that bad before but the rods and the rockers and valves were in poor shape. So now that the heads are new I do have better gas milage and a little more power.

so just in case this might be another alternative for you to investigate

good luck