Intake cam lobe lift is supposed to be a helluva more than .028", try .280".

4.6 and 5.4 have the exact same lift, as they are they same exact cam. PI 2V heads and cams are all exactly the same, regardless of what they are installed on. The only differences are cam gear fastener method (press fit or bolt) and cam cap assembly (individual caps vs cages) for Romeo or Windsor built engines, port shapes and cam specs are identical regardless of plant. The only way the lift will be less is if they are NPI cams. I think your mechanic is just talking out of his ***.

 

I am having the exact same issue. What did you find out??

 

All operating system reference begins at the crank sensor.
The crank has a tooth ring that passes by the sensor with one gap for the computer to reference from.
From this the ignition fire order is found and followed.
The cam gear passing by the cam sensor on the driver side times the fuel injection to inject just after the intake opens to draw air and fuel into the cylinder.
For there to be a backfire, the plug would have to be sparked with the intake valve open.
It's as simple as that.
Something some one is doing is causing the issue.
Is it the crank sensor, the cam sensor, injectors or coils plugged up in proper order or ?
Good luck.

 

Remanned motor. New pcm,new sensors,good compression, front cover is off and timing is good. Dealership has no frickin clue. I dont think anybody can fix this! I want to hang myself....

 

Lets start over again to find the present state of affairs.
1. Does the engine crank without backfire?
2. Does it start and idle without back fire?
3. Will the engine accelerate with backfire?
4. Do any codes set?
5. What is the fuel pressure?
You need to have the dealer answer each accurately in order to proceed.
Some one is making the same mistake each time they work on the problem.
You cannot have a replacement engine do the same thing twice unless a mistake is being made..
A new PCM and sensors won't correct a mistake.
This is either sorted out by some one who cares and knows the procedure or the truck is junk to you and are forced into a large loss.
Everything cannot be good and still not work without an error being made.
.
I will attempt to explain the difference in fuel injection and ignition timing.
A. As the intake valve opens and piston is on the down stroke, fuel is injected so the cylinder has fuel to ignite.
B. Only after the intake valve has closed and the piston is nearing top of cylinder does ignition occur.
You can see the difference in time between when fuel injection occurs and Ignition occurrs.
For a backfire into the intake manifold to occur, the ignition would have to occur before the intake valve fully closed and fuel injection would occur 'even earlier'.
The Injection order is set in computer program and reference from the camshaft position sensor.
The Ignition fire order is also set in computer program.
The reference for them 'begins' at the crank sensor/ toothed wheel location for the computer to get it's starting point..
.
It is a simple matter to check valve timing by moving the crank to position #1 cylinder at top dead center for compression and 'look' at the position of the intake valve. Both intake and exhaust valves has to be closed.
If only one bank is out, you check the other side the same way using cylinder #5 up on compression.
If either valve is open, that is your problem and someone made a mistake timing the Cams..
.
Again look for a mistake in harness plugup and be sure the fuel pressure is near 38 psi and not low causing a very lean condition and possible backfires.
If the shop only tells you it's all ok, your not any farther than before.
Take it to another shop that wants to solve the issue and will recheck everything.
You have no other choice.
Print this out and take it with you.
Any shop that takes the job is inferring they know how the system works and will do what is necessary to solve all issues related to the original agreement.

Good luck.

 

2 different engines and both backfire. hmm..... someones got this truck screwed up. you need to back up. and like said above, you also need to take it to a shop that knows what they are doing. you have it at a Ford garage? if they don't know whats going on with it...................Id sure wonder why.........Its a Ford in a Ford garage......

 

The previous mechanic had i stalled the lower intake improperly!! No more backfiring tbrough the intake now but we have #1#5#8 cops out. And the previous mechaninc also otched up the power steering pressure line. I had ot towed back home to finish this myself. I paid ford $2350 to tell me what the first guy did wrong! Hopefully this nightmare ends soon, and thank you all for the knowledge. I now a better understanding of how these mod motors work!

 

That's good news in a way except for what it cost you.
The cylinders that are out, see what code is set.
If in the 35x list, it is open primaries, if in 30x list, it is secondary issues with the boots or plugs.
Be sure everything is plugged up in proper order.
Hang in there and you will get it straightened out.
Good luck.

 

#3#5&#8 coils were non functional.
I got a set of pretty red cops off of craigls list brand bew $85. New hp power steering hose (previous mechanic didnt put the oring back in)
22 bucks. Runs great. Great throttle response. Still takes a while to start, sometimes. But all and all its definitely drivable. I never thought this day would come. With a couple of tools i had to buy. I spent $137. Dealership wanted to charge me 1800. >:/

 

Ah huh, aren't ya glad you came here and took our beating?
When your in the forest long enough all the trees look the same until some on else comes along.
Good luck, send check etc.