Hey all

so just reinstalled my motor. Got everything reconnected, primed the oil galleys by turning motor over without crank sensor plugged in. Reconnected crank sensor and motor fired immediately but had a large misfire - checked wiring.
check engine light still on dash and occurred to me - does the computer need to be reflashed to reset factory settings?

thanks
S

 

No, not if you are using a 4.0l and its a 4.0l computer
If it had code and CEL on before it needs to be cleared, but if battery has been unhooked for awhile they should self clear in a few days, assuming all sensors are hooked back up

Spark plug wiring, it ALWAYS gets me on these
3 4
2 6
1 5
front

The 5 6 4 side always gets mixed up

 

its the stock 4.0l computer

so its
3 4
2 6
1 5

I thought it was
3 5
2 6
1 4

I think thats my problem if I understand you correctly thanks Ron

 

Yes, engines are balanced in Matched Pairs, for the 4.0l, and 3.0l and most V6s, they use 1/5, 2/6, and 3/4, these pairs are both at TDC at the same time to balance the spin of crank
Ford uses Waste spark so there are only 3 coils in that coil pack
[3 4]
[2 6]
[1 5]

So these are sparked in Pairs when at TDC, one cylinder on compression stroke the other on exhaust stroke, so exhaust stroke spark is "wasted", hence the name waste spark ignition
Waste spark was the very first spark system used, back in the late 1800's, and single cylinder engines still use it, spark is timed by crank so sparks at every TDC

 

thanks Ron
just to make sure I understand.

engine cylinder order:
3 6
2 5
1 4
front of engine

engine firing order:
[3 4]
[2 6]
[1 5]

 

or are you saying engine cylinder order is:
3 4
2 5
1 6
front of engine

 

Ford uses this for cylinder numbers
3 6
2 5
1 4
Front

Coil pack wires are
3 4
2 6
1 5
front

So wire 1 goes to front cylinder on passenger side
5 goes to center cylinder on drivers side




Chevy(GM) uses this for cylinder numbering, just FYI
5 6
3 4
1 2
front, lol, odds and evens

 

thanks again

 

ok so went back through - confirmed wiring is correct as per above. Still MAJOR misfire at start up. what else could I be missing?

 

Well a cylinder fires when it has 3 things:
Spark, at the right time
Air/fuel mix in correct ratio
Compression, above 120psi

What year is the engine?
1990-2000 is 4.0l OHV
2001-2011 is a 4.0l SOHC
There are a few differences, but spark isn't 1 of them

If you have a compression gauge its best to take that off the table right off the bat, because you can waste ALOT of time on spark and fuel when its a compression issue
Remove all 6 spark plugs and test one cylinder at a time and write down results