Check Engine! HELP!

[Jeff00000168]

Ok, so I have a 98 Explorer XLT 4X4 with 100,300 miles on it. The check engine just lit up right now. What could be the cause of htis. Engine sounds normal and good. Oil levels perfect. Could it be the timing belt? Is this normal for the explorer's engine light to light up when it reaches 100,00 miles? I need some info before I bring it in for service tomorrow! I don't want to spend an arm and a leg.

Thanks in advance!

 

[ExplorerDMB]

We can't help you until we have a code - It's just shooting from the hip at this point. You may replace twenty parts then read the code and it says "fuel cap leak" and all u have to do is tighten your fuel cap and its gone.

Point being: get the vehicle scanned then bring it back to here and we'll help you out as best as we can.

-Drew

 

[mynameisaric]

go to autozone.. they read codes for free. it should be a PXXXX. if you get a specific O2 sensor code, it could be your O2 sensor, BUT dont go replacing O2 sensors. if you get codes that say that both banks are running lean or both banks are running rich, then you have a vacum leak, intake gaskets need to be replaced. Other things that could happen are your MAF sensor is faulty and needs to be cleaned or replaced. same goes with the TPS.

So go get the code read and give us the numbers, and we can narrow down your solution. i had codes pop up AFTER i replaced my intake gaskets (P1409) and the definition of that code was something to do with my EGR, and i could have replaced it, but the real problem was i left some wires unplugged during the reinstall of everything.

have you done any recent engine work? if you mess with your intake, its easy to leave your MAF unplugged putting it back together, and that will throw a code, but your truck will definitely run funny so thats probly not your problem.

 

[Jeff00000168]

Ok, I got the code. It's P1120. Fuel Air Metering Control. It said "THROTTLE POSITION SENSOR OUT OF RANGE". Should I bring my truck in for service at the Ford Service Center or Pep Boys or can I do this myself? What would be the best thing to do?

Thanks guys!

 

[mynameisaric]

if you know what the throttle is on your truck, you can find the TPS(throttle position sensor). and thus you can probably do this yourself. i havent messed with the tps myself, but if you have a voltmeter, you can probe the wires going into it and check the voltage which should be around .96 or .97 volts i think.

apparently on obdII trucks like yours and mine, it doesnt matter what the tps gives out for a voltage, because the computer will take whatever number it gets at startup and set it as idle.. (or something along those lines) but if your tps is giving out a number like 6v(which i think is WOT or close to it) then you might need it recalibrated.(you can do it yourself)

some guys are against it, but if you unplug your negative cable from the battery terminal, and leave it off for about 10-15 minutes, it will reset your computer. this will clear the code, but if the problem still exists, the light will go back on in a drive cycle or two. but reseting it, may allow the computer to reset its tps idle voltage.

or it might need to be replaced. i'm not sure how much they run, but checking your tps voltage or reseting the computer are worth your time before spending the money.
this is the link to the tps mod ---> http://www.explorerforum.com/forums/showthread.php?t=79362

i'd say its worth a shot before you take it to the stealership.

 

[marragtop]

If the truck is running ok, unhook the battery for 5 minutes to reset the codes. It may have just been a false reading. If the light comes back on, replace the TPS.

 

[Jeff00000168]

Thanks guys! Thanks for the link mynameisaric! I'll probably do it this weekend.

 

[Jeff00000168]

Ok, I haven't fixed my problem yet but last night while I was driving, the "check engine" warning light just disappeared. Does this mean that my throttle position sensor is within range now? My truck has been running the same even before the "check engine" lit up 6 days ago.

 

[DeathsArrow]

If the truck is running ok, unhook the battery for 5 minutes to reset the codes. It may have just been a false reading. If the light comes back on, replace the TPS.

I read somewhere that unhooking the battery doesn't clear the codes, it just turns off the CEL until something else trips it again.

 

[mynameisaric]

unhooking the battery, clears the computers memory. it has a specific name, but i cant think of it. theres 3 type of memory in the car's computer. one is programmed in and cannot be changed. another type is more like firmware, and you have to reprogram it, but it will not change if you unhook the battery, and the third is like the RAM in your home computer. the third type is where the CEL indications are kept. if you unhook the battery, you clear the CEL codes. when the car starts back up it reads P1000 < that means the memory was recently cleared. It takes 1 or 2 drive cycles for a problem to trip a CEL, and takes 3 drive cycles to clear a CEL on its own.

Jeff, if your codes cleared themselves, your problem may have just fixed itself somehow, or the computer adjusted or something along those lines. When you start your car, make sure your bulb didnt burn out just to be sure tho.

 

[Jeff00000168]

Before starting the car, 2 key clicks, the check engine lights up. Upon ignition, the check engine light disappears. Is this a good sign?