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Discussion Starter · #1 ·
Ok heres one thats got me....

I installed new motorcraft double platinum plugs around 10k miles ago, when I did so I cleaned and made sure they were gapped EXACTLY to .051 inches. Now 10k miles go by and my idle seems kinda rough...so I check some stuff and then finally decide to check the plugs. They still look great, but all the gaps were off by a lot! Only one was still at .051. What causes them to "De-gap" and is this normal? If so how often should you like recheck them?
 

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You should never clean plat plugs, the plating comes off. You gotta figure for a 1.80 or so a plug your not getting too much actual platinum content.
 

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I'm fairly certain that spark plugs do have an increase in the gap as they age - I can recall looking in my Toyota Factory repair manual for the old MR2 and it had specs for what the gap should be if the plugs are new, and what the gap should be if they are used - and those were platinum plugs, also. Why that happens I don't know but I'm gonna guess it has a lot to do with the high-energy spark flying across that gap a bazillion times a second, and of course the destructive nature of a controlled burn happening over and over again in each cylinder, also many times per second.
 

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Re-read your post, yes the gap does increase over time. It's a sacrificial metal the burns away over time. IMO it's not really worth all the trouble to clean and gap plugs, especially on a 4cyl. It's only 10 bucks to replace em all, and that shouldn't need doing very often, even changing them once a year would be overkill unless you have other problems that need addressing. Plat+4 is just a gimmick. Sounds good to have 4 seperate arcs igniting, but electricity will only flow to the electrode with the least resistance, and the 3 other electrodes surrounding the tip are actually shielding the flame from the air/fuel mixture. AFAIK all platinum plugs come pre-gapped, the manufacturers don't want the coating scratched off by people sliding the gauge in. One more thing to consider when gapping plugs, you need to use a spark plug gapping tool, the feelers are round wire. The flat blade feeler gauges don't read plugs correctly.
 

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Discussion Starter · #6 ·
ok I understand, but my plugs seem to be changing in the gap too quickly. Ive checked this a few times and it doesnt stay properly gapped. It changes like every 5k miles or so and then they're all off again, WTF is that happening?
 

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EuroZX3Focus said:
ok I understand, but my plugs seem to be changing in the gap too quickly. Ive checked this a few times and it doesnt stay properly gapped. It changes like every 5k miles or so and then they're all off again, WTF is that happening?
[scratch] Are you using the correct heat range?

I just dug out that old Toyota manual and it says (concerning platinum-tipped plugs), "never use a wire brush for cleaning / never attempt to adjust gap on used plug / spark plugs should be replaced every 60,000 miles"

I think the first two warnings are for what someone said earlier, that the platinum coating is *very* thin and easily removed. I dunno what Ford says about how often to replace the plugs.
 

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Discussion Starter · #8 ·
by cleaning I meant I blew on them to get the carbon off LoL, as far as heat range, I dont know how it would be wrong they are the OE plugs from the ford dealership
 

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I was reading through some other posts and noticed a lot of people talking about rough idle. Is this specific to any particular model focus or is it pretty much all of them across the board, including the SVT?

A few posts said the rough idle could be the version of the software in the car? I also noticed a few mentioning fuel type, and again I noticed people talking about different plugs. I am curious as to how much of this is really pertinant??

I have a fairly stock 2000 ZX3 that idles real rough. It seems to run fine otherwise. I have the Bosch +4 Plat plugs, a screamin demon coil, a AEM cone filter on the stock intake tube, 9MM Ford Racing wires and I have been running premium gas which i think here is about 91 octane but I dont remember offhand.

What is the general understanding about this combination??? Do I need to change something, or should I just live with the rough idle???

Oompa
 

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rough idle is only a problem with the SVT generally.

if i were u id ditch the bosch +4 they are very bad plugs for our cars, burn too hot. get the autolite double platinums and im sure your idle will be a lot better. also make sure your maf is clean too, it should be but just in case u can clean it with a cotton swab and rubbing alcohol be very gentle. and u should run 87 unless u have a chip. there was a thread a week or so ago where we discussed it if u wanna surch around on why
 

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what about the denso iridium plugs-can they potentially damage the engine?,by burning 2 hot or sumthin-(new 2 all this spark plug stufff)
 

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Discussion Starter · #15 ·
I would think that those would burn too hot, but Im not sure maybe its just that the Iridium can withstand higher heat? Ive never heard of anyone using those in a focus, I would be careful
 
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