rough idle, low power, sulfer smell in '03 Ztech

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#1
I am the proud owner of a 2003 Ztech ford focus. It came to me with 106K miles. It drove very very rough, so I did the motor mounts, which brought to light a rough idle and low power, which I somehow couldn't perceive through all the rattling. Spark plug 4, when pulled, yields no change in the motor's rhythm. I replaced all spark plugs, the discoloration in plug 4's core-nose insulator is very un-even, all of the plugs have black/grey coloration, not tan/brown and not at all gunky. Nothing oily comes off on my fingers when I wipe the tang of the old plugs.

Since replacing the plugs, I stall even more easily and the idle is actually worse. Cylinder 4 still is not firing. They came from the factory with a gap of .050 - .055" which I'm told is usually OK, but the old plugs that I believe came from the mfg were a step tighter, .044 up to .05.

I applied a volt tester to plug wire #4 with regards to continuity, it seems normal or better relative to its brothers.

Since changing the plugs, I get a sulfur smell in the cab. Does a mis-adjusted gap effect the way the fuel burns, and could the preset gaps be a contributing factor to this sulfur smell? There was no funny smell before doing the plugs, but I did have the power issue and the arrhythmia. . The check engine light is not coming on through all this. I haven't had a problem that causes the light to come on (Except stalling), so I dont know if the diagnostic actually works.

Thank you for merely reading all this. Sorry for the long post. I am not familiar with etiquette on this board. I'm doing all of my own everything on this car, I don't have a mechanic that I trust in this city. No disrespect intended to any professionals here.
 
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Thread Starter #2
Self replying here. Attached (hopefully) is an image of the NEW plugs, having only been driven for 10 or 20 feet and idled for 20 minutes. The cores are already radically different, attached is a picture. If there's anything to be read from these plugs, I would be interested to hear somebody's interpretation.
 
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Thread Starter #4
It's me again. I am going to disconnect the fuel pump and let the spark plugs hang out of the cylinders, so I can look and see if all are firing. I'll connect them to the frame for ground.

The fuse box diagram does not reflect the box in situ. It says that the pump (#12) uses a 15 fuse, but the actual fuse reads 30. It says that 11 is ABS and 13 is unused, but my 11 is empty and 13 has a fuse in it. Is is possible that the diagram is correct, and these variations are not important? Thanks in advance.
 
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Thread Starter #6
Plugs are autolite, which I think is the same as motorcraft? Wires look like new, volt meter gives 2.7 at 20K resistance for the short wire.
 
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Thread Starter #8
The CEL is not on (trying not to make any assumptions), and no way to connect to the on-board at this time. Probably I will limp to the auto parts store to do the coil, I believe they'll let me use their ODB scanner
 

inventiv

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City
Sydney
State
Non-US
Country
Australia
What I Drive
2002 Ford Focus Mk1
#9
Replace plugs with standard copper plugs such as the Motorcraft ones. In a Focus the platinum or iridium plugs actually don't yield as good a spark. Also, HT Leads are often overlooked. Here is a vid on how to replace all of it at home:

 

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