Hi everybody. I've been a member here a little while but mostly just lurked around gathering information, but I'm at my wits end with this thing and could use a little help.

1997 f150 4x4 super cab has 4.6 with vin w, but has had an engine swap at some point.
Problem is that it floods like crazy on the very back cylinder drivers side. Runs very rich to the point of smoking. Have replaced the plugs (motor craft fine wire) wires( auto lite pro) both coil packs and the injector on #8. I'm about 300 in this fixing this skip and I'm out of ideas. Maybe the computer is bad making number 8 hang open all the time? I thought I had it fixed before when I swaped #4 plug and injector with number 8 but it started back again within 200 miles. Frustrated I just replaced the whole ignition with no success. Compression checks normal no water in oil or vice versa. Any help is appreciated.

 

The computer has solid state drivers just like the coils do for opening the injectors on a timed basis.
My guess is an intermittent 'ground' or cross in the harness or it could be the driver in the computer.
Never saw an injector driver go bad but it's always possible.
All the injectors and coils have 12 volts standing on them from a common source so all it takes is a ground from some source to operate them individually just like the computer does..
If you can catch it at idle and put a Noid lite on it may show near solid lighting instead of the normal blinking.
An analogue voltmeter would provide the same indication with needle movement as the indicator. Look at a good cylinder then the bad one to compare.
On the bad one, move the harness around to see if there is a reaction.
Good luck.

 

Tried a modified version of the blink test. Used my test light backwards while hooked to a constant 12v source and checked it against the ground side of the number 8 injector plug. Was averaging 1 blink per skip as best I could tell.....back to square one lol

 

So it's not these:

Plugs/Coils/Injectors.

Considering the ECU controls the firing order of the injectors and "pulse width", i.e. how long the injectors spray for, I would think there could be a potential issue with the ECU solders being old/broken and causing this issue.

Does it go away when you unplug the battery and reset the ECU?

 

Unplugged battery and turned switch 5 or 6 times before I did a flash test on the injector. It did flash like its supposed to.

 

I guess I could check the spark plug to make sure it fires at the right time. Spark at the wrong time is worse than none at all right?