I did a 5.4 to 4.6 swap would I have too change the computer also?

Tiny
DAMIEN12
  • MEMBER
  • 2000 FORD EXPEDITION
  • 120,000 MILES
The engine came out of a 99 grand marquis
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Tuesday, July 17th, 2012 AT 12:25 AM

14 Replies

Tiny
ASEMASTER6371
  • CERTIFIED MECHANIC
The computer is set to the 5.4. Not much difference except some fuel control issues. I would try it to see how it runs before getting a new computer.

Roy
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Tuesday, July 17th, 2012 AT 12:41 AM
Tiny
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I already place the engine in and its runs good but it has a stall to it and it smokes real bad and I was wondering would that computer make it smoke
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Tuesday, July 17th, 2012 AT 3:28 AM
Tiny
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If it is giving a rich command, yes. The 5.4 requires different fuel settings and that may be making it run rich or it may be an issue from the other motor as well.

Get a shop to monitor the computer trims and tell you what is happening

Roy
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Tuesday, July 17th, 2012 AT 1:20 PM
Tiny
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Can I use the computer out of the car that the motor came out of instead of going thru trying too drive it too a shop
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Tuesday, July 17th, 2012 AT 3:33 PM
Tiny
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No, the vin is burned into the computer and if you use that one, it most likely will not run from a vin mis match. You may be able to have the current one flashed by the dealer. Call a dealer service department and see what they say

Roy
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Tuesday, July 17th, 2012 AT 3:35 PM
Tiny
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I spoke with a mechanic at the ford dealership and he said he couldnt flash the computer over to a 4.6, he told me too just get a 4.6 computer to put in there, how do that sound?
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Tuesday, July 17th, 2012 AT 3:46 PM
Tiny
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Not right if he means a used one. The computers are the same, they just need different information

Roy
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Tuesday, July 17th, 2012 AT 4:49 PM
Tiny
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Well I did get a 4.6 computer and the truck started up and shut off and when I try too start it up it wont stay running
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Tuesday, July 17th, 2012 AT 10:33 PM
Tiny
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I have installed a computer and a mustang before and it done the samething and when I went back too it the next day it ran perfect do you think I need too give it time to reprogram?
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Tuesday, July 17th, 2012 AT 10:36 PM
Tiny
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It does not reprogram itself. They have to be flashed.

It sounds like a security issue. Did yours or the donor have a security light?

Roy
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Wednesday, July 18th, 2012 AT 3:43 PM
Tiny
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Yes it does have a security light
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Wednesday, July 18th, 2012 AT 6:01 PM
Tiny
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That alone will stop it from starting. It would have to be programmed at ford to release the security lock

Roy
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Wednesday, July 18th, 2012 AT 8:17 PM
Tiny
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Ok could I have the 5.4 computer that came with the expedition flash the the motor that I put in
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Thursday, July 19th, 2012 AT 3:11 AM
Tiny
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It goes by vin number and yours will show the 5.4. You need to speak to the dealer about this. They may be able to enter the code for the 4.6 if it was available for your truck. Yes, the 4.6 was an option. Give it a try

Roy
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Thursday, July 19th, 2012 AT 1:43 PM

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