Originally Posted by JMC

I am not going to turn this thread into a debate over which of the Modular engines is best suited for the F-150. The intent of this thread was to inform members who wanted to swap a 5.4 in place of their 4.6. In hindsight I should have never answered any of the above posts.

Originally Posted by JMC

Notes for 4.6 to 5.4 swap Part 2 Revised 04 April 2015

PCM and Tuning: it should start and run using the 4.6 PCM so if it doesn't there is something wrong with the wiring or a sensor. That is assuming t hat the 5.4 engine is mechanically sound. It is best to have a custom tune done to accommodate the extra displacement of the 5.4 when using the 4.6 PCM. You should be able to use the 4.6 MAF as any competent tuner can adjust for it. It is always best to discuss this with your tuner.

Knock Sensor: The 97-98 99 4.6 uses a 2 wire knock sensor. The 97-98 5.4 has 3 wires of which one is a ground for the shield. Both have a Yellow /red wire to pin 57 on PCM.
1997-98-99-2000-01 Yellow/red to 57 on PCM 4.6 Same for 5.4.
97-98 Pin 91 feeds power for 4.6 and other components. Same for 5.4
1999- 2000-01 Pin 32 for power. Same for 5.4
2002+ Cannot confirm.

Accessories: Some engines have 8 rib serpentine belts and some have 6. Be sure to check so that your accessories have the correct pulley. The original alternator, Air Conditioning compressor, water pump and power steering pump can be reused by changing the pulleys. You also can cheap out and use a 6 rib belt on an 8 rib pulley.

PATS (Passive Anti-Theft System) : The 1999 model year saw the introduction of the PATS as standard equipment on the F-150. If you try to use the PCM from a PATS equipped truck (1999 +) on a non PATS equipped truck (1997-98) you will run into wiring problems. The instrument cluster in PATS equipped vehicles communicates with the PCM and they share security data. The work as a pair and if you use a different PCM they will need to be reprogrammed to work together. For a PATS capable PCM to function in a Non PATS vehicle the PATS function in the PCM must be disabled. So a 1999+ 5.4 PCM in a 1997-98 truck will need to have its PATS disabled. 1999+ 5.4 PCM in a 1999+ 4.6 Truck will need to have the PCM configured to the 4.6 instrument cluster or have the PATS disabled.

Misc: Both engines use the same engine mounts and their location on the block are also the same so your old ones will fit. Unbolt and place aside the AC and PS. You need to remove the intake manifold for the engine to come out. Yes there are 3 bolts on the starter.

Originally Posted by JMC

Notes for 4.6 to 5.4 swap Part 1 Revised 04 April 2015
Application: These notes cover the F-150 from 1997 to 2004 Heritage model years. They do not cover swaps to a supercharged 5.4 engine.



Before you start: All you are doing is putting a bigger displacement motor in place of your 4.6. I recommend you use your 4.6 ignition and PCM along with its engine harness.

Cylinder Heads: The following info applies to the F-150 and not any other vehicle engine.
4.6 Engine: The 4.6 engine had Non Pi Heads from 1997 to 2000. The Pi heads were introduced to this engine for the 2001 model year.
5.4 Engine: The 5.4 engine had Non Pi Heads from 1997 to 1998. The Pi heads were introduced to this engine for the 1999 model year.

Exhaust: The collectors on the exhaust manifolds are set at different angles and locations. The 4.6 exhaust might not bolt up to 5.4 manifold. You may need to have a muffler shop modify your 4.6 exhaust to match up.

Ignition: All 5.4 engines use Cop ignition. . 2000 and later 4.6 use COP ignition. 1997-99 4.6 engines use coil packs. It is easier to wire your 5.4 using the harness from the 4.6 and use the 4.6 ignition coil packs if applicable. If you use the 4.6 Coil pack ignition you will have to fab a bracket for the driver side coil pack.

Engine harness: To use a 4.6 PCM to run a 5.4 engine: The IAC harness must be relocated to the rear of the throttle body elbow. The oil sender wire on the 4.6 may be too short so measure or test fit the harness to see if it must be extended. All 97-00 and some 2001 4.6 engines use some sort of intake manifold runner control valve. Remove it from the 4.6 and plug it into the 4.6 harness and bolt it to the engine some where out of the way. Note; you can get a tune to remove its function and eliminate it all together.
All 97-98 4.6 engines use an Engine Coolant Temp sensor (ECT) and an Engine Coolant Temp sender. By the 99 Model year the ECT was dropped in both the 4.6 and 5.4 harness as the Cylinder Head Temperature sensor (CHT) was used for the PCM to monitor coolant temps. None of the 00+ 5.4s use ECT sensor or sender. Some of the 99 5.4s still use the sender to feed info to the instrument cluster. You will have to tap the intake manifold crossover pipe to fit the sensor(s) if your 4.6 has them and the 5.4 doesn’t.

Transmissions: the 4.6 and 5.4 have the same bellhousing bolt pattern. That means that all the transmissions will bolt up. All the 5.4 engines have 8 bolt crankshafts. Some 4.6 engines (ROMEO ENGINE) have 6 bolt cranks. You will need the flex plate from the 5.4.
Manual transmissions: If you don’t have an 8 bolt flywheel a flywheel from a 1997-8 4.6 Windsor engine will work. As it has 8 bolts it will bolt right up to the 5.4 crank. Remove the flex plate spacer and install a pilot bearing from a 4.6.

Special note about the different automatic transmissions and their respective harnesses. You cannot run a 4R100 transmission with a PCM that had a 4R70W transmission and vice versa. The transmission harnesses are different and will not plug into the different engine bay harness. The control functions in the PCM are not compatible so the transmission will not function properly.


Torque Converters:
4R70W
ENGINE............Stall Speed............Multiplication
4.2..................1978-2330...............2.3:1
4.6..................2105-2505...............2.3:1
5.4..................1830-2190...............1.9:1

4R100
All Engines......??????....................2.2:1


If you swap a 5.4 into a 4.6 engine bay and use the 4.6 converter you will multiply the 5.4's torque at a higher rate and at a higher stall speed which will put the torque at the transmission input shaft close to the limit if not over the limit of the 4R70W. The 99+ 5.4 produces 350 ft/lbs of torque. 90% of that is available at 2000 rpm. The stall speed of the 4.6 is above the 2000 rpm range so more than 90% is available. 350 ft/lbs x 2.3(4.6 multiplier) x 90% is 724.5 ft/lbs.

Originally Posted by JMC

Notes for 4.6 to 5.4 swap Part 1 Revised 04 April 2015


Engine harness: To use a 4.6 PCM to run a 5.4 engine: The IAC harness must be relocated to the rear of the throttle body elbow. The oil sender wire on the 4.6 may be too short so measure or test fit the harness to see if it must be extended. All 97-00 and some 2001 4.6 engines use some sort of intake manifold runner control valve. Remove it from the 4.6 and plug it into the 4.6 harness and bolt it to the engine some where out of the way. Note; you can get a tune to remove its function and eliminate it all together.
All 97-98 4.6 engines use an Engine Coolant Temp sensor (ECT) and an Engine Coolant Temp sender. By the 99 Model year the ECT was dropped in both the 4.6 and 5.4 harness as the Cylinder Head Temperature sensor (CHT) was used for the PCM to monitor coolant temps. None of the 00+ 5.4s use ECT sensor or sender. Some of the 99 5.4s still use the sender to feed info to the instrument cluster. You will have to tap the intake manifold crossover pipe to fit the sensor(s) if your 4.6 has them and the 5.4 doesn’t.

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