I have a 98 with a 4.6w with 130K miles. It has left me stranded 2 in the last two days because it will run fine for about 30 miles/ 30mins... then it won't idle and stalls.... if i try and start it again, i have to hold the go pedal to the floor and if it starts it runs REALLY rough. The codes i've gotten are 1121, and a high circuit input IAC, and a high circuit input for the coolant temp sensor as well.
does anyone have any idea what might cause the truck to just start running this poorly? I cleaned the MAF sensor but i'm feeling that might be the problem sensor. any thoughts?
Try unplugging the mass air sensor at next shut down. It should run if it is the MAF I was told this works on all sensors except the throttle position. I have tried it on the Mass air flow and even drove it for a week till the part was shipped. It goes into a default mode and is hard on gas.
It sounds like a MAF wire busted or very dirty- could be the TP sensor, mine went once on my 98 and maannn, they really act up when that goes..
I agree completely. (hey, jbrew.... quick! look outside and see if there's some pigs flying around or little frozen demons popping out of the ground)
As cheap as the TPS is, go ahead and change it. The do wear out and they get dead spots in the area where you used the throttle most often (just off idle). Pull the MAF, get a can of MAF cleaner, or some non-chlorinated brake cleaner, and spray the living **** out of the 2 wires in the air path. Blow the whole can on it, hell, blow 2 if you're feeling froggy. Let it dry thoroughly and reinstall. Reset the computer (pull the neg. bat cable for a few minutes) and go drive it. It should run rough for a little while as the computer re-learns the drive train, but that's normal. If that doesn't fix it, you might need a completely new MAF sensor. Plus, while it's out, check to make sure there's no foreign matter caught in the wires of the MAF. Sometimes crap gets stuck there and can cause problems.
Are you running a K&N filter, or any other oiled gauze type????
Thanks for all the replies... hopefully i can answer all the questions:
Just bought the truck a month ago with #3 cyclinder known bad. pd. 2100 for truck.
MAF sensor was completely covered in crap. cleaned as to recommendations on this site..... same can of elec. connector cleaner.
TP sensor was replaced 3 weeks ago.
The wires in the MAF sensor apear to be intact.
No audible vac leaks. but will check more indepth on that tomarrow.
the first code was the coolant temp high input, i cleared it with scan tool. 2nd was 1121, cleared with scan tool... 3rd IAT high input. cleared with scan tool... then numerous 1121 codes, each cleared with scan tool.
The truck runs GREAT until whatever is causing this happens then it runs like crap. The wire harness looks good... no visible damage from heat or from being pinched.
PS: after i got the coolant temp high input reading i checked the gauge and sensor as per a hayes manual... appeared fine. According to the gauge the truck never ran close to being hot... about 1/3 to 3/5 on the gauge at idle with the a/c full blast (yes it's winter and yes i live in FL !! )
The TPS, IAT, ECT all share a common signal return lead to the PCM.
That lead is probibly going open. This is the high indication.
Look at the connector at the PCM and the harness from it out to the engine.
Should be pin 91.
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