Been a while since I've needed to post about this thing. 1999 xlt, 5.4 w/ 258K miles. Had a high idle when I pulled into a store parking lot this afternoon. I had to put it in 4x4 to park decent because the rear tires would spin too easily on the watery ice while there was enough brake to hold the fronts. Anyway, I watched it hold 1500 -1600 rpm for a while, thinking it might settle down, but it didn't. I shut it down and did my shopping, and when I got back, all it would do is turn over. Seemed fairly quickly I'll add, like when the PATS key doesn't get recognized.

 

Check your throttle cable where it attaches to the side of the TB. There's a plastic piece that can break and get stuck under the cable making it do that.

No DTC's ? Scan it anyway, - with or without CEL illumination.

Then start at fuel delivery , the pump. Rule out a fuel problem.

 

Thanks for that tip, the throttle cable is messed up there slightly, never given me issues before, but I'll check that for sure when I get back down there this evening to pull codes. It was too noisy around me to hear any fuel pump activity at that time.

BTW, thanks for the response. Your a huge help on this board. I haven't been around much lately, but your name is one of the few that stands out in my memory from when I used to have to ask about my problematic truck here often, years back. Even your posts in my searches yield tons of info and you seem to be involved in everybodys issues. Thanks again.

 

Is the 4x4 controlled by vacuum on this model. Sounds like a vacuum leak.

 

You might be on to something there. I've been putting up with 4x4 slipping in and out.

 

Mine wouldn't come out 4wd last night, - very cold tho, windows froze shut as well. After about 5 miles or so, everything working again.

Even my blower speed **** was frozen lol.

 

It started back up when I got back to it last night. Almost made it out of the parking lot when it started running a little rough and that's when I seen the oil light was on. I shut it down and towed it home with our Expedition, that's what I had planned on doing anyway. Code reader pulled p1288 - cylinder head temp sensor out of range. Throttle cable looked it's normal broken self, not jammed up or anything though. I could here the fuel pump. Has oil, looks alright. Low coolant, but I do have a leaky block heater. I'm going to go poke at it some more and see what else I can come up with.

 

Replace the CHT. If the PCM is getting a low temp input from it, that could sure cause a high idle and rough running.

 

Mt chilton manual doesn't seem to mention this at all. My searches reveal another PITA part to replace - not surprised but dissapointed in the design of this motor AGAIN. Anyway, I want to test this before having to remove anything. Is there a test procedure?

 

Now that I can see it better in the light, it looks like this sensor is right on the front of the drivers side head?? Right in the open after the intake plenum is off. Now I'm not sure though because everything I've read so far says it's under the intake, and there is a set of wires running right where I'd expect there to be if this is the case.

Working on this thing is bit of a bear right now, outside, on ice. Everything is coated in ice right now that was outside that last few days. I have to walk about 50' on uneven ground that is glare ice with water on it. At least is warmer than usual at about 32F right now.

This motor is actually a 2003 if that matters any.

 

Nope, it's not the sensor on front of the head. It's under the intake, I can see it now with my fingers when I reach in there. What a mess, down in there.

 

Sensor tested really high resistance so went ahead with the repair. Got the sensor out easily enough. Just had to remove the alternator. The connector broke off while I was fiddling around trying to get a wrench on it, so a short 1/2 inch 19mm socket went over it and with very short turns was able to break it free to allow the wrench to slowly do it's job with similar short turns. It looked like it was falling apart already once I got it out. I already bought the part I needed the day before, but turns out they gave me the wrong one. I'll have to return it and get the right one tomorrow. They gave me Borg Warner part wt3058 and I need wt5059 according to the website. Anybody think it's necessary to spend almost twice the dough for a 3 year warrenty vs a 1 yr on this?

 

Got it all fixed up last night. Took it for a test drive and all is well again.

I broke my first replacement part trying to screw it down with a modified gear wrench. as I was turning it down, the thick head on it pushed the connector out of the sensor. I got a new one from car-quest ($10 cheaper), that luckily had a slightly thicker hex head which made a big difference in how much the wrench would have to grab onto. I also used a regular craftsman 3/4" wrench and slowly tightened it all the way down without popping off the connector. IT was a bit of pain to only be able to turn it maybe a 16th of and having to flip the wrench each time. Patience in the end paid off since I didn't have to remove the intake.