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Discussion Starter · #1 ·
have just had my 1999 DISCO II 4.0 engine swapped out for a 4.6L from a '03 disco II. I had the 4.6 engine installed with the wiring harness that cam with it and also the 4.6 ECM that also cam out of the same vehicle as the 4.6 engine. However here is the issue.

I took the vehicle to dealership and they said that the following would have to happen:

1. I would need to have the 4.6 ecm re-programmed so that it would look for the secondary air intake stuff that all newere 4.6 engines have (I took the intake off and plugged the four holes because I did not have all the other secondary air stuff). This 4.6 ECM is looking for that stuff and can't find it so the check engine light will always be on.

2. The wiring harness from the 4.0 would need to be put on the 4.6 because even thought thee ends are identical, the wires are spliced differently along the lines. So even if I put the 4.0 ecm back in the vehicle (which the car runs fine with in, but without the gains that the 4.6 ecm would give) I would still get error codes (evap codes) because the wires are coming from different sources than what the ECM is looking for all related back to the non-existing secondary air intake stuff.

3. He/the dealearship cannot re-program the 4.6 ECM to not look for the secondary air intake stuff and he doesn't know where I can get that done.

Does all of this sound correct? Do I really need to switch out the wiring harnesses or does anyone know of the splices that I can just change? Where can I get the 4.6 ECM reprogrammed so it won;t look for the non-existant secondary air stuff.
 

· Former LR tech, Albany NY
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yes, without secondary air on the truck the ECM will look for it.

And if you need to change over the wires then simply solder new connections.

you got yourself a very long job ahead of you.
 

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Discussion Starter · #3 ·
beezel said:
yes, without secondary air on the truck the ECM will look for it.

And if you need to change over the wires then simply solder new connections.

you got yourself a very long job ahead of you.

Is it easier/will it work if I just put back the 4.0 wiring harness and the 4.0 ECM?
 

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Discussion Starter · #5 ·
I had a 4.6 engine with only 12,000 miles on it and my 4.0 needed the usual valve job and also had lower end knock. So after talking with two different LR dealerships that relayed that the swap could occur, I went ahead and had it done by a local garage.

The local garage just kept the harness that was on the 4.6 when they did the install and took out the 4.0 harness with the 4.0 engine. I now have the 4.0 ECM in there with two evap error codes:

P0447 Evap control vent open
P0453 Evap pressure switch high
 

· Former LR tech, Albany NY
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2,437 Posts
thats a really obscure one. I would need T4 to get an idea where to go. I mean it could be something messed up or two wires in the wrong place.
 
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