Ok so some new problems have surfaced. I have the exhaust back on and it is sealed (no excessive noise), and I also replaced both upstream O2 sensors. I started the engine to check fuel trims and noticed that there seems to be a constant misfire, but I'm not getting a misfire code. Short term trims on Bank 2 were perfect, but Bank 1 started at 26% and climbed up to 42% before I shut off the engine. The only code I have is a DPFE code which was there before I started the entire project. Using my stethoscope, I narrowed the issue down to a hanging injector on cylinder 1. It was barely clicking and all I could hear was a "whoosh" sound like it was not closing nearly fast enough. Like it opens nearly normally, then slowly slides closed or something. The resistance checks out at 13ohms, so it must just be dirty. I assume that it's so rich that it wasn't igniting, causing the lean code. That is not the only issue. I also noticed something new or something I didn't notice before, but most likely would have if it was there the whole time. There is now a moderate amount of white smoke coming from the exhaust. I know this screams coolant leak, but I've also read that raw fuel can cause this (mostly diesel but I've read about gasoline causing this as well), especially in the case of a stuck open or hanging injector. Unfortunately, the smoke smells what I imagine coolant would smell like. After killing the engine, the remainder of the white smoke slowly flows out of the tailpipe and falls toward the ground. Kind of like dry ice fog. If anyone's ever seen what vapor from a vape pen looks like, it's nearly identical. Since the vape pens contain propylene glycol and antifreeze contains ethylene glycol, I imaging it has to be coolant. I did however look into the coolant reservoir and there were no bubbles while the engine was running and last time I did the compressed air leak test, there were no bubbles. Today I retested compression on all 6 cylinders (only dry). From 1-6, the results were 165, 165, 155, 210,210,220. The specs that I found say no lower than 100psi and no greater than 70 psi difference between the highest and lowest, so I'm sitting on the edge of normal. It seems very strange to me that one bank is so low and the other is very high. For this compression ration, 220 seems almost too high. So I was thinking that the only thing that could cause such a difference between the two banks would be a slipped timing sprocket like I was worried about before and never checked. This would not explain a coolant leak though. Tomorrow I'm going to improve my set up so that I can control the compressed air going in to the cylinders better than I could before and see where the compression is going. Last time I did this, I am certain I found DTC on cylinder 1, but air was rushing out of the intake, so I had to turn it until I could hear that both valves were closed. I can't remember how much I had to turn it, but it was at least an 1/8 to 1/4 turn. First I guess I'll have to take care of cleaning the injectors with an ultrasonic bath which I still need to order, but I'll also check the timing while I have the intake off. I'm really starting to hate this engine for how much work it takes just to get to the injectors. It takes me about 15 mins on my Suburban to get to the injectors, while it takes about an hour and a half on this one. I know that I could just loosen the intake plenum and try to push everything out of the way, but I'd rather not have to struggle. I could probably get the heads off my Suburban also in the time it takes me just to get the injectors off the Sport Trac. Anyway, probably shouldn't be bashing Fords and praising Chevy here, but what is with the complexity of this engine? It definitely has nothing to do with reliability, that's for sure.

Hi Nick,
The on time of the injectors is what you are reading and the higher # is because not enough fuel is getting into the cyl/bank.
Because there is extra oxygen at the O2 sensor as you know means not complete burning. Does the misfire go away when you raise the RPM ?
If so , you are looking at a vacuum leak on that bank. You could be right about the injector and if you can, check the other injectors on that bank as well.
I don't know the condition of the O2 sensor on bank one, so I would consider switching it with bank 2 to see how much if any difference we get.
Think about this,
If the injector is barely clicking , it most likely is not because it is dirty but may have an electrical supply problem. I know it is a PIA to switch it with another cyl,but that way you can narrow down some of the possibilities.If you can , confirm that full power(voltage) is available at that injector and the same for the ground that the PCM supplies.
That smoke you see could be the result of the high injector on time that the cyls can't burn all that fuel.
Tell us you did not put any old O2 sensor on that bank, did you?

Well O2 sensors only sense oxygen and there is a 14:1 ratio of air to fuel. So if the fuel does not ignite in that cylinder, neither will the oxygen, so both pass through and the oxygen only gets read. Now if it were igniting, it would probably make the O2 sensor read rich. There is a spark though so it must be way too rich to ignite or something. I could be wrong, but I've read this in a couple different places. Both upstream sensors are brand new NTKs. I was using one that I spliced on from my Suburban but the readings did not change with the new O2 sensors anyway. The NTKs are all they had in stock but they seem to be a good brand. Bank 2 is reading normally, so the sensors are most likely compatible. I didn't check to see if the misfire goes away with higher RPM and I already have the injectors off. I tested the power to the injector with a test light and it pulses as it should and it reads 12v. If I blow through the bad injector, you can very easily tell it is stuck open slightly. The others do not let any air through. As I said, the resistance on all of them is between 12 and 14 ohms. I removed the filter baskets and all but one were completely deteriorated, so I assume either there's gunk or pieces of the filter basket stuck in there. I'm going to try spraying compressed carb cleaner in them while pulsing them with a 12v power supply, otherwise I'm going to order an ultrasonic cleaner and a new set of filter baskets. New injectors are out of the question for now. Maybe a single replacement, but the whole set is probably not worth the money at this point.

I've never understood how there can be a vacuum leak on only one bank, since the entire vacuum system is connected. Also, the intake ports are separate from each other, so how could air possibly be leaking into only 3 cylinders? I'm going to check the timing on bank 1 since half the top end is already removed anyway. As far as vacuum leaks go, I noticed the PCV valve was not in its hole, but that's on bank 2. Also, it's a one way valve and there's usually positive pressure in the crank case, so this shouldn't have caused the problem. How would you explain the lack of compression on bank 1 vs bank 2? I've been searching and searching for answers but couldn't find anything. The only thing I can come up with is a timing issue on that bank since it was very hard for me to properly torque that cam sprocket bolt since the engine was in the vehicle and my torque wrench was most likely not calibrated correctly.

Go ahead and blame it on the torque wrench !! lol
It would be a good idea for you to save these posts and look back over them as you become a little more experienced,
Wonder if your thinking might have changed some .
As far as the 4.0 being a dog to work on, that will not change , pretty sure of that.

If you have a means of pulsing the injectors in milliseconds , OK, but if you put 12 volts to any of them, plan on replacing it .

You don't have to take my word for it.
If you have a spare injector around , try it !

I got the sticky injector to work consistently after using an ultrasonic bath and pulsing 12v through them. Also, I was right to suspect that the timing on bank 1 had slipped (pic below). I reset the timing and will report back later to say whether or not I'm still having problems.https://cimg1.ibsrv.net/gimg/www.for...d8599ecda6.jpg