zeekracing

My friend has an 03 f150 that had a 4.6 in it. He just installed a 5.4 DOHC motor out of an 01 lincoln navigator. He is using the 4.6 harness. He put the 4.6 fuel injectors in it becuase of the differant connector that the 5.4 injectors had and he has the 4.6 computer on it. He does have the computer that came out of the navigator. The motor will turn over and acts like it is trying to start but will not. I have no clue on these later fords. What do we need to look at to try to figure this out. Thanks!

TheJMC

The Navi DOHC engine uses 24# injectors your F-150 uses 19# injectors. Either buy connectors or adaptors for the navi injectors and use them.

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torkum

You can get the connectors at www.fordracingparts.com

zeekracing

So the computer for the original 4.6 will work?

blackbetty

no

TheJMC

You will never know if you don't get the injectors working. There is the question of intake manifold runner controls but that is secondary to fuel issues.

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TheJMC

The main difference between these engines besides the number of cams is the fuel supply. The DOHC is designed for Sequential Fuel Injection and your 4.6 is batch fired. This may lead to flooding at start up so it is important that all the sensors are correctly attached and functioning. Try starting in the clear flood mode. That is press the accelerator all the way to the floor.

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ONELOWF

If you are using the 4.6 pcm, which thinks that it is running 19#ers, it might work better with the 19#ers installed.

Maybe the 4.6 maf as well.

zeekracing

Does it make a differance which maf is on the vehicle? I've messed with a lot of late model gm but not ford. Is it the same as the older fords where the maf and injectors are a matched set?

ONELOWF

The pcm has no idea what engine you have put in there, but it is programmed for the 4.6 maf with 19# injectors. I beleive it will run OK with those in place, but at higher engine load, the injectors should deliver but the maf may run out of capacity. So, the maf will tell the pcm that the air mass is not increasing, and the pcm will not add anymore fuel which will create an unsafe lean condition. Boom.

This combo should be custom tuned with larger injectors and maf to run right.