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<!-- BEGIN TEMPLATE: ad_showthread_firstpost_start --><!-- END TEMPLATE: ad_showthread_firstpost_start -->finally completed the 4.6 to 5.4 converstion......everything for the most part bolted right up, a few diff mods were needed....anyways it's pretty much all finished but it's not firing yet....my guess is that it's not getting fuel or spark....my first guess is a security/theft system....or computer not egnoliging the new motor properly.....code reader would not work on the truck for some reason. it's still the factory 4.6 computer in the truck, I still need to buy a programmer for the computer, but I know very little about that device.

So up until this point I have no fuel pressure at fuel rail. I have attempted spraying gas in the intake and still not firing. Do you have any ideas or has anyone been through this and have any tips to help?
Thanks in advance

 

I'm about to make the 4.6/5.4 swap myself. Other than what you listed as far as it not firing up, what other issues did you have with the swap? What headers did you use? Where did you get your 5.4? Did the wire harness from the 4.6 work with the 5.4?I would appreciate your input.

 

The tuner is no biggie. It plugs into OBDII port and follow the directons.

 

You have a blown fuse which is why the code reader won't power up.

What year truck are you working on?

 

the truck is a 2003...

issues I've had:

the motor I installed was from a (believe to be) 1999, 2 wheel drive van.
I used 4.6 wiring harness rather then 5.4 because it didnt match up every where exactly.
Injectors connectors were different, simply cut out and resoldered from other harnest. There were a few other connections that didnt match up 100% so I just swaped the sensors. Had to keep the 4.6 oil filter brackets due to 4 wheel drive. Heavily suggest keeping existing exaust from 4.6... Will bolt up to 5.4, Other then that the trans (4r70w)...I had to buy a flex plate/fly wheel that had 8 bolt holes mounting it to the engine....scrap yard. computer has to stay the same due to it operating the tranny also. drivebelt much larger, therefore you may want to get the bigger pully's for the powersteering pump, altanator, AC compressor....and a new belt of course. on the van engine the throttle body is on a 45 degree angle facing the driverside corner, I bolted the old throttle body back on it, much easier....I had to heat the pcv exhast tube up and bend it down a bit, be careful not to burn a hole threw it like I did....had to reweld it closed again. the odd emissions ***** had to bolt up anywhere it fit.

 

I'm still needing help here, truck turning over but still will not fire, now getting fuel at the fuel rail properly, searched every fuse, none are popped, obd2 reader is now working, it's not picking up any codes but the emissions stuff is flashing on the page. drivers side exhast from mainifold back is not hooked up because I have to get the exhast angles welded back to original. Does anyone have any other ideas where I should start? plugs for spark? thanks ahead of time.

 

oh, I also forgot to mention.....when I split the wiring harnesses to make one from the two of them I found that in the differant yrs of the motor they changed the crank sensor wiring to be the complete opposite, the positive was said to be the neg and so on, therefore I changed it....I'm thinking tomorrow I'm going to cut the wires and cross them back over to original.....also the fully charged batteries that I keep using seem to be draining way to quickly. only about 3 to 4 cranks and it's toast. could a crank sensor be the cause of the truck not even attempting to fire.

 

found cause of engine not firing, it was the crank sensor wires reversed. After changing around the truck was firing but not starting. Also had a few wires in the wrong spot for the COPs, corrected and is now running!