Simple Thermostat change turned into headache !!! help ?

[TheMightyThor]

Soooooo....

Friday morning I brought my 2000 Expedition XLT ( 5.4 Triton ) in for a check engine light... P0125
I have the mechanic change the CHS... Code goes away but the temp gauge never goes a little above C, a symptom I have noticed for about 2 weeks.

I decide to change the thermostat this morning myself... went easy, had a little trouble getting the housing off after i took the bolts out but a little coaxing and she came right off... minimal leakage up until I took the thermostat out, then she started to glug heavy for about 15 seconds... probably lost about a half a gallon... I put the new thermostat in, new O ring, put her back together, torqued down the screws and DONE... put it all back together started it up and let it warm up then took it for a ride.. Ran great ! smooth, temp gauge sat at half way ( like it should ) and drove around for a good half hour.. no leaks, no issues lots of power etc.. parked it somewhere dry so I could check for leaks later on...

3 hours later I came out to take my kids to the movies... started up the truck, once I got about 100 feet she started to shake alot and feel like it had no power., but the engine still ran smooth, tranny shifted smooth etc...
drove around and it still persisted.. This was NOT how it was a little while ago... stopped at my mechanic as he was leaving and he popped the hood, said he wasnt sure but didnt have time to really look it over and it wasnt showing a Check Engine light...

as soon as I pull out of the lot, Check engine light goes on.. so I go to Autozone..

its showing a P0125 AGAIN ( which I just had the sensor changed, and new thermostat ) and its showing another code for a Cylinder #5 misfire...

So... my question is... do I assume that antifreeze leaked into the spark plug well and is causing my misfire? If thats the case.. Why 3 hours after sitting when the test drive went so well ?? Should I change the Coil Pack on the #5 cylinder ? I was thinking of pulling the coil pack, using compressed air to blow out the well and then installing a new one.....

any advice would be great... I want to avoid a major repair bill here....

the P0125 I am bringing it back to the mechanic for.. if the sensor he put in is faulty again, he is fixing that no charge ! ....

 

[bedrck46]

what year model and engine always nice to have that information

 

[TheMightyThor]

2000 XLT 5.4 V8 Triton

 

[bedrck46]

P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control

Indicates the ECT or CHT sensor has not achieved the required temperature level to enter closed loop operating conditions within a specified amount of time after starting engine.

Insufficient warm up time
Low engine coolant level
Leaking or stuck open thermostat
Malfunctioning ECT sensor
Malfunctioning CHT sensor

Thermostat Monitor
The Thermostat Monitor is designed to verify proper thermostat operation. This monitor will be phased in on certain applications beginning with the 2000 model year and replaces the original "Insufficient temperature for closed-loop test" (DTC P0125). This monitor will be executed once per drive cycle, after a two hour, engine-off soak period. If a malfunction is indicated by the thermostat monitor a diagnostic trouble code P0125 will be set and the malfunction indicator lamp will be illuminated.

The monitor checks to see if the engine is being operated in a manner that is generating sufficient heat. While the engine is at moderate load (greater than 30%) and the vehicle is moving (greater than 15 mph/24 km), the ECT or CHT should warm up in a predictable manner, therefore, a timer is incremented. The target timer value is based on ambient air temperature at start-up. If the timer exceeds the target time and the ECT or CHT has not warmed up to the target temperature, a malfunction is indicated.

The target temperature will be calibrated to the thermostat regulating temperature minus 20°F (11°C). For a typical 195°F (90°C) thermostat, the warm-up temperature would be calibrated to 175°F (79°C).

Inputs: ECT or CHT, IAT, engine LOAD (from MAF sensor) and vehicle speed input.
Output: MIL.

 

[TheMightyThor]

right... the P1025 code we got today said something to the effect of PCM has verified engin running at proper temperature

the temp gauge is acting normally now, which it wasnt before.. that is what led to the change of the thermostat in the first place ???

my main issue right now is not the P1025 so much as the #5 misfire

 

[bedrck46]

is it possible that when you changed the t/stat that some coolant got into the spark plug wells? also I assume you installed the t/stat properly

Pull the COP and blow out the spark plug well with some compressed air get some dielectric grease and fill the boot or even replace the boot Autolite makes replacement boots as well as motorcraft

 

[bedrck46]

being the t/stat housing is very close to #5
I tend to think that is what caused the misfire If you do change the plug or any time you change plugs Make sure you torque them to specs when reinstalling

How many miles on the expy? when was the last time plugs, boots and COPS were changed?

 

[TheMightyThor]

yeah, I'm going to definitely pull the COP and see whats up... I am almost certain that I got coolant in the plug well, I have noticed that driving it just before that the symptoms have lessened to a degree when going to pick up dinner. I picked up a new boot and grease and will check it out in the AM, I will let you know what happens...

I have never changed anything I just got the truck a few weeks ago... I plan on doing all the Coil packs and the plugs soon just been doing things little by little. I do believe the plugs have been changed before at some point according to the previous owner but the coil packs look original.

 

[bedrck46]

again just make sure you torque the plugs to specs 15ft/lbs

 

[1stGeExpedition]

Make sure the thermostat isn't installed upside down.

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