Hey Guys,

I recently bought a f150 4x4 king ranch, i am having an issue with the thermostat jumping to HOT and the reduce engine power is coming on. I have put 2 computers on the truck both have read the Control head temperate plug, well i replaced that, and the reduced engine power is still coming on. The truck does not seem to lose power, if you turn the truck off sometimes it will come back on, sometimes it wont, either way the truck seems to run fine. Any suggestions of what the problem could be?

Thanks

 

Having a hard time understanding what you are saying - you say that you have replaced the cylinder head temperature sensor?

Have you replaced the thermostat? Have you tried using an infrared thermometer on the thermostat housing to see if it really is overheating?

 

Yes sir i have replaced the cht sensor. The truck is not actually running hot, its a false reading. From what I have read the throttle body can cause this issue, along with a few other things. But i am trying to narrow it down.

Once the reduced engine power light comes on, you can pull the truck over and shut it off. Once you crank the truck back up all the settings are normal, but after a few miles the reduced engine power light will come back on. The truck seems to have the same horse power. Each time the reduced engine power indicator comes on. The Cold/hot Gage is pegged out too HOT. I stop and check the truck each time just for caution, then i press the system check inside the truck and it says engine temp OK each time.

Secondly the truck is not wanting to pick up speed properly, its sluggish. The transmission fluid seems okay, and the only time it seems to struggle to shift from 30-50 mph, but the rpms never go over 2400. Never grinds or sticks or anything, abnormal.

 

Exactly my problem. Googling found it could be a lot of things. What fixed yours?

 

clay34 seems to have left us. I personally, think this is a programming fault in the PCM/ECM. I suggest you take your truck to a dealership and see if there's an ECM flash that can fix it. They may have a TSB about this issue.

- Jack

 

I have seen so many posts about this same issue, but cannot find a definite solution from anyone. Did any of you figure it out?

 

Let me address this a different way.
What is being described is a fault that is causing the PCM to set a code and function for engine overheat >>or<< loss of oil pressure.
The code is for "Limp" mode that takes cylinders out in rotation, to keep the engine from damage from overheating. This would be the loss of power.
The Limp mode has a code assigned.
Has anyone bothered to look at the code to be sure?
Has anyone bothered to put a Scanner on the system and actually observed the cylinder head temperature when the fault occurs?
The causes can be a false signal due to a wire issue, a thermostat sticking closes, a blocked radiator, low coolant level, faulty fan clutch, water pump fins gone.
Is the engine actually overheating?
Do the testing to see what is going on instead of guessing and wondering.
I sure hope your Doctor don't guess, change parts etc when your feeling ill or have some problem.

 

There is a cylinder head temp sending unit and there is a coolant temperature sending unit. They do differ, CHTS and CTS are not the same.

 

I don't think 2004+ has a CTS, just a CHTS, the PCM converts CHT to CT?

 

I am not technical as most of you seem to be. Here is what I do know. I know that randomly the reduced engine power light will come on. When this happens the temp shows on my dashboard to be as hot as it can be. But...I know the truck is not overheated and the truck is not in limp mode. The performance of the vehicle is completely normal and it is not overheating. That has been verified. I was thinking it would be a sensor of some sort because it is false. The guy who works on my truck was hoping to narrow it down before he just starts replacing things that may not need replaced. Thank you.