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Discussion Starter · #1 ·
Hi Fanatics,

This is my first post, having an issue with my wife's '04 SVT, only mods are a drop-in K&N air filter and Tom's Tune that was loaded about 6 weeks ago. According to my wife yesterday the car started sputtering and bogging, she thinks it was somewhere in the middle of the rpms and at mid-throttle. She got home and had a p0302 CEL for mis-firing in cylinder 2.

To see if it was anything with the tune I switched back to stock and the problem remained. From what I could find the typical causes are usually ignition related so I pulled the plug wires and plugs to check, I've attached some pictures of them, in the picture they are in order with cylinders 1-4 from left to right. The wires seem ok and the plugs look pretty much the same across all of them, but I'm not very confident that I can read the plugs correctly. Strangely the rubber ring around the middle of the one from cylinder 2 was on it when it came out, I guess maybe it's part of the plug wire but can't see where it should have been. Please check out the pics and tell me what the rubber ring is/means. From that I'm thinking plug wires and plugs as well if needed, but if you wise and experienced folks have any advice I'd really appreciate it.

Also, I've read on here that the coil is often the culprit, haven't checked that yet but I'll take a look when I get home and try swapping the plug wires to see if the problem moves to a new cylinder. To diagnose misfiring in cylinder 2 I should swap plug wires 2 and 3 on the coil to see if the problem moves to cylinder 3, correct?
 

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That rubber ring looks like it came out of a spark plug socket-it's there to hold a spark plug in place while you thread the plug into the hole.
 

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Discussion Starter · #3 ·
Dude, I'm dumb, you're absolutely right. After taking out the #2 plug which has the ring on it I was able to unscrew but not lift out the next plug until I switched to a different spark plug socket, that's definitely where the ring came from. Thanks!

So with that part aside, how do the plugs look? I'm guessing that it's going to turn out to be the coil since the plugs all look pretty similar, but I'm still at work, will check when I get home. If the coil is the problem are those plugs still good or should I just throw in some new ones while I'm at it.

And on the same line, should the plug wires be fine? I know there's some way to test them and see if they spark, with a screwdriver or something, but I'm not very clear on what to do or look for. Can anyone advise?
 

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Start with a fresh set of plugs, those have been in there a LONG time.
 

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Discussion Starter · #5 ·
Thanks for the advice, will do. They are probably the original plugs unless the previous owner changed them, so likely close to 90k miles on them.
 

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Then a waste of time putting them back in. The rust belt around bottom of the porcelain says the spark could possibly be leaking down outside of plug to short to the outside lower metal case. These are bad about that.

The only way you can check plug wires is by the resistance per foot of wire, or 5000 ohm per foot and no more. You need a cheap voltmeter for that, Harbor Freight was giving them away free last week if you bought anything at all.
 

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Those plugs do look done. While you are at it, get a multimeter and check the wires and coil pack as well. A good multimeter can save you a whole world of guessing. Find a digram for your coil. 1 and 4 should have continuity and 2 and 3 should have continuity. This is a regular ZETEC diagram but I'm pretty sure the wiring is the same for the
SVT coil pack: http://repairguide.autozone.com/zne...96b43f/80/24/2f/8e/large/0996b43f80242f8e.gif.
 

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SUP Memphian!

It doesn't look like you're dealing with any extreme engine control problems except for old plugs. I recommend going through all the things that make for a "tune-up" on these vehicles. Then see what that fixes.
1) Clean the air filter, since it's a K&N, you'll need to purchase some spray MAF cleaner, and clean your MAF 2x afterwards for about a month because the oil will upset the readings.
2) Clean the MAF
3) Change the fuel filter (check on here for How-To's, all Focis up to 08 have the filter in the same place)
4) Plugs and plug wires, I always recommend lifetime warranty wires because you can change them whenever for free and cross a potential cause off your list- even if you might've just gotten a new set a short time before.
5) SVT special stuff- inspect your intake tubes. Look for cracks, dry rotting, etc. Several suppliers sell alternatives to the factory tubes made with more exotic materials. Those tend to last about 10 years or so. If one does develop a large leak, the car won't run.
6) SVT special stuff- check out the DSI clip. The clip that holds the DSI arm to the actuator breaks, and when it does that will cause engine running problems, loss of power, etc.
 
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