High idle/Engine Temp

[Kiloaman]

Vehicle: 1999 Explorer, SOHC 88K miles. K&N air filter with gibson catback.

Problem: Engine overheating, high idle and funny shifting at my 1-2 gear.

Problem description: Engine idle is around between 1000 and 1500 rpm. Engine temperature is about 2/3 at normal driving. It increases when rpm is 2000 and above. I can overheat the engine by holding the gas at 3000rpm for about a minute. The funny shifting only occurs when downshifting from 2 to 1, the rpm jumps to about 2000 rpm, then returns to the idle at around 1500 rpm.

Attempted solutions: Already checked for vacuum leaks, disconnected the battery, check both oil and trans fluid (are ok). Also have cleaned the MAF and butterfly valve and checked the TPS (at ~.97V).

Possible solutions:

1) Because it's idling high, and the engine is overheating, I'm thinking a bad water pump. This would increase the idle, because 1) the engine has to work harder to turn it (if there is a bad bearing), and 2) overheat the engine because it's not being cooled.

2) Bad thermostat maybe.....

3) Your guy's input on the problem.

Thanks in advance for any advice, and yes, I have used the search option and came upon these threads and have read them.
http://www.explorerforum.com/forums//showthread.php?t=228571
http://www.explorerforum.com/forums/showthread.php?t=133593

 

[scucci]

Thermostat. Overheating causes limp home mode. Fast idle, delayed rough shifts may even missfire as part of the protection strategy the pcm is programmed for. My 98 did this last year. The temp gauge only showed a slight temp increase. The cylinder head temp is also monitored by the pcm and is what the pcm used to determine overheating.

 

[2000StreetRod]

Thermostat & coolant level

I'm assuming that you have the stock viscous fluid cooling fan and not an electric fan. If you have an electric fan, make sure that it is working.

Even a water pump with a bad bearing should not result in enough drag to overheat the engine. If it were that bad the serpentine belt would slip and you would hear it. Make sure your coolant level is normal. I agree with scucci that you should try replacing your thermostat. It's the cheapest and easiest thing to try.

The SOHC has an engine coolant temperature sensor that is independent of the temperature sending unit for the instrument cluster. It allows the PCM to monitor the engine termperature and adjust the fuel mixture as the engine warms.

 

[Kiloaman]

Bought and installed the new thermostat, all is good now. No more erratic temperature gauge or funny shifting.

 

[Mickyfreeman8991]

Thermostat & coolant level

I'm assuming that you have the stock viscous fluid cooling fan and not an electric fan. If you have an electric fan, make sure that it is working.

Even a water pump with a bad bearing should not result in enough drag to overheat the engine. If it were that bad the serpentine belt would slip and you would hear it. Make sure your coolant level is normal. I agree with scucci that you should try replacing your thermostat. It's the cheapest and easiest thing to try.

The SOHC has an engine coolant temperature sensor that is independent of the temperature sending unit for the instrument cluster. It allows the PCM to monitor the engine termperature and adjust the fuel mixture as the engine warms.

I'm having the same issues. I've replaced the water pump and thermostat along with the housing.

 

[EB4X]

Same issues as in high idle and still overheating ?
If high idle did you thorough checks for vacuum leak? ...any hissing sounds from engine compartment ?

 

[donalds]

Thought I'd add
I ran into this problem
Same exact symptoms

It was the fan clutch