OKay well I'm only typing this once because if you use the search feature you can read for 3 days how to do it.
MAF:
-Go to Pep boys or wherever and buy yourself some security style T bits. These are the star bits that have a hole in teh center. If you look at the screws on your MAF sensor you will know what I am talking about, and they are great to have around when your buddy needs to clean his MAS.
-disconnect the - battery cable
-ONce you have the right bit in hand, unplug the wire harness from the mas sensor (screwdriver or packet knife, be careful, dont break it)
-Pull the plastic sensor from the aluminum MAS housing out straight up. Careful!!! dont bend or touch the elements on the ned of the sensor!!!!
-If you look at the sensor itself you will see two little wires running across, similar to the filiment in a light bulb, you may notice some light brown buildup on the little "hot wores" you may not, either way it;s probably dirty.
-Hold the sensor out and spray the carb cleaner on it, the goal here is to remove any buildup on the hot wire elements, so you dont need to soak the entire thing, just spray the little wires themselves.
-Let them dry!!
-re-install the o ring, and re-insert the sensor into the MAS housing, careful! you dont wont to bend the hot wires, they are fragile and MAS's are expensive to replace.
-re-install the security screws and wiring harness.
-go drink a beer
-hook the - battery cable back up and you are done.
Now I am aware that this proceedure does not work on all years, some of the later model trucks (darkfox this is you) have a big ass plastic housing around the MAS sensor and you cant exaclty remove the sensor from the MAS body, deal with it. Spray the carb cleaner in there as best you can, let it dry, re-install. The important part is to disconnect the battery so the computer can re-learn the new signals the clean MAS is sending.
Idle Air Control Valve:
-disconnect the - battery cable (same reason as above)
-Unplug the wiring harness from the IAC (again careful, pocket knife or screwdriver, dont break anything!!!)
-Unscrew the two 10mm bolts that hold the IAC assembly to the upper intake manifold. Be careful not to damage the gasket!!!
Take the IAC to your work bench, kitchen table, backyard, whereever you want to do the work.
-Remove the two phillips screws that hold the electronic sensor to the IAC body, set the electronic solenoid aside (it doesnt get dirty)
-Look at the IAC closely, a flashlight is good for seeing in there. Open and close it a few times, it's spring loaded, this will give you an idea of how this little sucker works. Just like it's called; The computer sends power to the electronic solenoid and this opens and closes the valve, allowing a precise amount of air to bypass the the throttle body, thus controlling the engine's idle.
NEato!! right?......................... boring.
You will see there is all sorts of black carbon built up on the little plunger inside the IAC.
-Spray a ton of carb cleaner into both sides of the IAC, let is soak for a few seconds. Get out your q tips, about 30 of them. Get busy, careful, you dont want to leave a ton of cotton behind. Make sure you open and close and turn the plunger several times while cleaning so you get the carbon off all 360 degree's of the round little sucker.
-let it dry, for a long time, make sure it is bone dry before you put it all back together.
-Dont be afraid to use the flashlight, look in there and make sure you got all the crap out.
-Put the electric solenoid back on the valve body with the two phillips screws.
-Put the gasket in place and bolt the IAC assembly back onto the upper intake
-hook the wiring harness back up
-go drink a beer
-re-connect the - battery cable
Fire up your 4.0L and notice the high idle, this is because you reset the EEC's memory and the engine now thinks it;s a new truck and it;s ready to re-learn the signals being sent to it from your now clean sensors (dirty sensors send different signals). Take the 4.0L for a nice leisurly drive, no hard core wheeling, no bracket racing, no jumping, just nice stop and go driving, this gives the computer a chance to re-learn and get you back in smooth operation in no time flat. When you get back most of your hesitation, loss of power, and rough idle problems will be gone, unless your fuel filter and throttle body are dirty, but thats another chapter...
I clean my IAC and MAS about once a year, the MAS sometimes a little more if I have been driving in the dirt alot, of course I'm **** when it comes to my truck so you might think I;m a little wacko, especailly after the beers you just drank..
