Engine change out
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Junior Member
Joined: Dec 2018
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From: Hagerstown, MD
Engine change out 2003 Ford F150
Has any one replaced a 4.6 engine with a 5.4? What problems will I run into? Any help will be greatly appreciated. Any major changes I need to do?
Last edited by ronblick; Feb 14, 2022 at 09:15 AM. Reason: Added. Year
5 Year Member
Joined: Dec 2016
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Not sure about the 4.6 - 5.4, but I do know when we swapped bodies on my son's 96 Bronco with 5.8 with a 94 Bronco originally with a 5.0, we had to swap the ECM, swap the entire under hood electrical harness, splice the HVAC harness to make it work, and repin some electrical connectors to the ECM on the firewall side harness under the dash. So in short, you will probably have to swap electrical parts and harnesses and repin and reprogram to make it work. With these computers, it isn't as simple as it used to be.
Good Luck
AK4wheeler
Good Luck
AK4wheeler
98 F150 5.4L E40D/4R100
Joined: Nov 2006
Posts: 28,519
Likes: 7,630
From: MI
Yes, you'll have to lengthen the IAC harness and exhaust to fit the 5four.
The original 4six tune will run the 5four, but it would be better to have the dealer flash the tune to 5four.
The original 4six tune will run the 5four, but it would be better to have the dealer flash the tune to 5four.
Last edited by Jbrew; Feb 14, 2022 at 09:37 AM.