I have a 1999 expedition with the 4.6L. I just bought this truck at the end of September. I have replaced the plugs and wires, but sometimes I still have a problem with a miss right after I start up. It was giving me a code for a miss fire and it would flash the check engine light when I would get on the gas hard, but the plugs and wires cleared that up. Since then it will run great some days and run like crap on others. I thought I would try this sensor since it was cheap, but is it easy to get to? If this is bad it will have an affect on my performance right?

 

Use the diognostics that are available, have the codes run again.

"Runs like crap", thats fun to say but doesn't help at all. Please define.

 

it runs bad and has no power like it is out of time.
It has no check engine light on now

 

If the running bad is really noticeable at idle, suggest look for a vacuum leak in the large hose that goes to the PCV valve, look at the elbows especially. An awful lot of posts hear about this.

With the dual overhead cam timing or the basic ignition timing, suggest going to a good shop.

 

The CHT is srewed into the cylinder head at cylinder # 5 and angles down into the valley. You can see the wires running out of the valley just under the thermostat flange. I'm not sure if you could get in there to remove it without removing the cyl head.

I am nearly certain that 99+ trucks use a CHT exclusively with no coolant sensor. The coolant temp is "inferred" from the CHT input. You cab verify this by looking at intake coolant crossover to see if there is a sensor there.

My year has both ECT and CHT sensors, and during datalogging the temps are very close.

 

I just took my head temperature sensor out after removing the thermostat hose and alternator. May need to drain a little antifreeze out first. Will lose some. Its a tight fit; but a 3/4 smaller wrench will get it out.

We'll see if a new thermostat and sensor fixes my mpg/idle problem. I'll
post again.

 

I have a 1997 F150 4.2 v6. I believe I have located the spot where the CHT sensor SHOULD be but IS NOT. There is just a threaded hole on the back side of the head up near the firewall. I cannot see any plug or wires that would have connected to the CHT sensor either, and I have even gone so far as to use an inspection camera.... still nothing. My question is can anybody tell me where the other end of the CHT sensor wires begin from so that I can try to follow them to see where the wires broke off? Then at least I could attempt to replace the plug and sensor. If anybody can help me with this it would be much appreciated.

Thanks

 

I'm not familiar with the 4.2 but 4.6/5.4 use cylinder heads that will go on either side, so there is always an open threaded hole where you have found one on those engines. Look at the back side of the other cylinder head at the front of the engine to see if the sensor is there.....probably tight for space......under the thermostat/hose and behind the alternator.

 

Hi all I'm hoping somebody can help I have an 03 f-150 4.2 XLT I went to change the cylinder head temp sensor and it broke off so the threads are still inside and the hole is still sealed the problem is I only have less then a 3" space from the head to the firewall so it's hard to drill it out, I used a small easy out tool and that broke inside, my question is, is there another spot I can put the new sensor? There is a plugged hole on the thermostat housing but it's not the same size sensor but I can buy one the only issue with that is the electric clip is not the same so do the sell an adapter and can I use the thermostat housing spot will that work? I failed inspection because my engine light is on the failing code is P0125 I live in New Jersey and the weather will be cold soon and my temp gange is always reading cold because the sensor is there anything else I can do without taking the head off the truck? Please help

 

The CHT is a dry senser element. Its not designed to be in liquid. So even if you swapped to a ECT and changed the pigtail more than likely the PCM would still throw a code for CHT out of range(either high or low). Your only bet with having the easy out broken off inside of the threads is pulling the head and taking it to a machine shop.