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2003 Centennial Last Project Vehicle

Today I took possession of what is probably my last project vehicle - a 2003 Explorer Centennial with a 4.6L SOHC V8, 5R55S automatic transmission and rear wheel drive.
The following threads are related to this vehicle:
Next project vehicle?
DOHC 4.6L V8 build
Motorized pre-oiler
4.6L DOHC head cooling and crossover delete mods
2003 Centennial 4.6L Engine Removal
ATF to Fluid Cooler for my 2003 Centennial

There were only 4,000 of these Explorers manufactured and they all were identical inside and out. They have black exteriors to match the only color available on the Ford Model T. There is a badge on each side and rear to identify the anniversary model. The Centennial is basically a more expensive Limited with some unique interior and exterior combinations. I prefer the black wheel well trim over the normal gray on the Limited and the gold on the Eddie Bauer.

The exterior is in decent condition considering the age of the vehicle and the mileage (181,800). There are no significant dents or dings but the paint on the wheel well trim is starting to show some wear.

The rear panel is broken which is typical for the 3rd generation.


There is virtually no rust on the underside.

Which is typical of a vehicle that has been located in Greenville, SC since new.

The leather on the driver seat is in pretty good condition.

The rest of the leather and all of the carpet is in very good condition.


Officially, I am only the second owner. The vehicle was purchased new by the parents of the seller and she never transferred the title into her name. There's not a lot of spare room in the engine compartment and I plan to use all of it.

My near term plans are to install:
ScanGauge II to read transmission fluid temperature (TFT)
Remote mounted full flow engine oil filter for ATF
Remote mounted full flow & bypass engine oil filters
Pod type engine oil pressure gauge
Electric pump engine pre-oiler
I'll probably remove the chrome side step bars that are fairly heavy & just in the way upon entering/exiting

My farther term plans are to:
Replace 4.6L SOHC V8 with rebuilt 2003 Aviator 4.6L DOHC V8
Install 2003 Mach 1 intake manifold, throttle body & plenum
Install billet fuel rails with mounted fuel pressure gauge
Generate custom tune using Advantage III software package
Beef up 5R55S transmission
Install Aviator front spindles and brakes

Eventually I might:
Purchase and install some type of forced induction
Install a "stealth" high performance exhaust system

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Three keys

I only received one PATS key and one remote with the vehicle because the other original set was lost many years ago. Yesterday I paid the county property tax for the next year and paid for the tag so today I was able to drive to my local PATS qualified locksmith to get two keys made. He used my existing key to cut two more microchip keys to fit the door and ignition locks. Then he hooked his machine to the OBD-II port and put one of the new keys in the ignition and turned it to run. It only took about ten minutes before the PCM recognized the new key. Then he disconnected the machine and used the two PCM recognized keys to program the third key. That only took about 10 seconds. The total cost was $100. Now if I lose a key I can get another one cut and program it myself.

Nice clean truck! I'm pretty sure the rear aviator knuckles are set up for larger brakes too. I want to say they use almost 13" brakes in the rear but have a smaller pad surface area.

Transmission fluid temperature

Excessive Transmission fluid temperature (TFT) is an indication of a potential damaging condition to the transmission. Racing, towing and hill climbing can rapidly increase the TFT to damaging values. Ideally, the TFT should not exceed 200 degrees. Operating at 220 degrees can cut transmission life in half. The TFT should never be allowed to climb above 250 degrees.

The 5R55S/W has a thermistor that allows the PCM to determine the internal temperature and provides it on the OBD-II bus. I can datalog the value with my SCT PowerFlash but wanted it to be visually displayed continuously. My 2003 Limited and my 2000 Sport utilize Ford's PWM protocol while 2004 and later models utilize the CANSF protocol. Two common aftermarket OBD-II based "gauges" are the UltraGauge and the ScanGauge that have pre-defined pids that are user selected digital readouts. The UltraGauge MX is advertised to be compatible with Ford's unique protocol implemented prior to the CAN bus standard. Unfortunately, it is unable to display TFT in 2003 and earlier models. ScanGaugeII has XGauges that provides the capability to define pids to be displayed.

I purchased a used ScanGaugeII via ebay. I first tried it on my Limited with the ignition on but the engine not running and it failed to connect. So then I tried it on my Sport and it immediately connected and displayed the "home" page. Referring to the user manual I selected the choices to get to the page to edit and save an XGAUGE. Then I entered the values for TFT.

TXD: C410F1221674
RXF: 046205160674
RXD: 3010
MTH: 000100080000

I was pleased that TFT in degrees F was displayed. I went back to my Limited to try again. This time I started the engine and ScanGaugeII connected. I set the default display to show TFT and the predefined parameters IAT deg F. (FIA), degrees advance or retard (IGN), and % of max power available (LOD).

I went for a short drive to let the transmission warm. Even though the ambient air temperature was only 56 deg F the TFT continued to increase above the 125 deg F when the external cooling loop was supposed to open. Upon returning home I left the transmission in reverse at idle and watched the TFT increase slowly to 171 deg F. I ran out of time so I selected Park and the TFT started decreasing. I concluded that the external cooling is marginal and will investigate improvements.

Lock/unlock remotes

I purchased a pair of lock/unlock remotes from an Amazon seller (2 KeylessOption Replacement Keyless Entry Remote Control Key Fob Clicker Transmitter).

The received package included programming instructions for a Focus, Towncar and Ford, Lincoln, Mercury which I followed. I did not follow the Explorer note about having one door open. All doors were closed and unlocked. I reprogrammed my worn but known functional remote first and rapidly followed with the two new remotes. The doors locked and unlocked after each remote was programmed. After the programming mode was exited I tested each remote and they all worked from a distance of about 10 feet from the vehicle.

Nice Find, never heard of centennial edition before or seen one. Subscribing--your work is incredible as always.

The cool fall weather has prompted me to resume working on my project vehicle. Last month the engine started to falter at idle so I replaced all of the spark plugs because they were worn to an excessive gap. None had signs of oil fouling or detonation. I want the engine to be running well when I pull it to begin swapping in the DOHC 4.6L. That way I won't have any qualms about selling it to someone who needs it. I installed Motorcraft SP-493 AGSF32PM platinum plugs.

Edit: The new plugs didn't fix the engine stalling at idle. I added a bottle of Techron fuel injector cleaner to the fuel tank but I'm beginning to suspect the idle air control (IAC) valve is not functional. I read the diagnostic trouble codes and there are none set associated with the IAC valve. I installed a new group 65 Interstate 1000/850 CCA battery since I have to restart the engine so often when releasing the accelerator.

Resolution: I cleaned the IAC valve with throttle body cleaner and confirmed the solenoid shaft would move and the return spring was not broken. The solenoid coil resistance was about 10 ohms and the electrical connection to the PCM and battery junction box was good. However, when 12 volts was directly applied to the solenoid coil the IAC valve made a sound like a loud buzzer instead of a hum. Replacing the IAC valve resolved the idle issues.
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