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Discussion Starter #61
I did a short idle with the cylinder 4 injector unplugged, the fuel trims actually ended up sticking together (bank 2 went to ~.78%). Here's a log with it: https://docs.google.com/spreadsheets/d/1wpHSBmdiGpvWlHNWnZH2NMZgr2_fA3Y3qbGP4EaY2V8/edit?usp=sharing
In the log I start with the injector unplugged, I plug the injector in, then I unplug it again. It should be fairly obvious when each action was taken as you'll see the fuel trims move.
Unfortunately the battery had died (small battery was off the charger) so the LTFT's were lost. I compared the temps of the exhaust pipes again and this time, with the injector unplugged, cylinder 4 was slightly cooler than before (around 20-40 degrees).

I tested the plug and it sparked without issue (no fuel, turned the car over, grounded the plug). I also tried another plug, nothing changed. I can't figure out which spark plugs spark at the same time, if I can I can try swapping spots on the coil pack I can see if the car starts running properly. Keep in mind, within the last month I replaced injectors, spark plugs, spark plug wires, swapped spark plug wires with a known good one (no change), and I also threw on a brand new coil pack.
 

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I think you are not seeing how things work

the 02 sensor detects 02...........

if the number 4 is misfiring, no explosion

that 02 is going in to the exhaust, with the fuel.....02 does NOT care about fuel

remove the injector, no fuel, YOU SHOULD expect the fuel TRIMS NOT TO MOVE.

the same amount of air is in the exhaust.......

can you see this?

take your test light to battery positive, verify it, by touching a ground source

then unplug the #4 injector, probe both pins on the harness, while the engine is running

what does the test light do?
 

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Discussion Starter #63
I kinda get where you're going. I think the confusion on my end is coming from what others keep telling me; if your plugs are wet from a misfire you're O2 is going to read rich.

At this point, what exactly do you think could be wrong? I'll do the test you requested tomorrow.
 

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your fuel trims, from your logs, do not match what would be expected

I am not sure who these 'others' are, but I know 02 sensors only create a voltage when there is a 02 pressure difference between what is inside the pipe, compared to atmosphere

how much raw fuel is in the pipe, matters not

when you are thinking this out, you must totally understand this concept, otherwise what the ecm is doing will never make sense

do the injector connector test light test, and we will go from there

reversed banks is still not out of the question
 

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Discussion Starter #66
I also traced back the O2 wires and the signal wires reach the ecu correctly. The ford wiring diagram book I have does not really delve into O2 sensors much, but from what I can tell they're wired up correctly.
 

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Discussion Starter #70
No problem, it's cylinder 4 injector, plugged into the positive and negative side of injector 4 pigtail. The tester is flickering. I just verified that the banks worked correctly all the way to the ecu, but I'll swap banks and record it.
 

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Discussion Starter #71
Here's a log of reversing the O2 banks. To make sure we're on the same page, I left the sensors in the same bank and swapped the harness, so bank 1 is plugged into bank 2's harness and vice versa.
https://docs.google.com/spreadsheets/d/1S89gdu3XLij5tpf7_zxpSb-OtKSIWUKqAbi04t-zIfk/edit?usp=sharing

If you don't want to look at the log, the fuel trim issue swapped banks and the car was still consistently missing.

I also pressurized and smoked the intake for vacuum leaks and I couldn't find any leaks.
 

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okay, sounds good

for spits and giggles

redo that same test on the injector harness, but have the engine off, key off
 

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Discussion Starter #73
You mean swap o2 banks and watch the #4 injector with the vehicle off?

If not, when the banks were plugged in correctly and the test light was plugged into injector 4, there were no lights with the engine off and key off.
 

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Discussion Starter #75
Ignition off, key off, there the test light is off.
Ignition on, car not started, the test light is off.
 

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okay, that is good test, that there seems to be NO short to ground on the ground side switch

the video, doesn't really show a distinct pulse, as i would expect, could be a frame rate artifact....

lets go over it a little

you have verified good strong spark, at the plug

you have injector pulse, and compression is normal

yet no power from that cylinder, dead miss

is this correct?
 

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Discussion Starter #79
Regarding the miss.. I'm not 100% sure it's a dead miss, but it's definitely missing. I've been using a laser thermometer to check the exhaust temp at each port, which is what helped identify there was a miss. Each time I ran the car, cylinder 4 exhaust was 40-60F colder than other cylinders. When I did the test with the injector unplugged, it was about 20-40 degreese cooler than that.
With that in mind, it's most likely late combustion with the often dead-miss. I'm not able to 100% verify this as I'm not a mechanic, but that's what I'm seeing at least.
You are correct on everything else you mentioned.
 

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well, we have exhausted common tool tests......

more sophisticated tools, like a scope and a scan tool are probably going to be needed

we would need see wave forms to see what is happening inside the comb chamber

do you have a good diagnostic shop around?
 
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