Spark plug questions

[tw557]

I was just checking to see if this was about normal. When I bought the car they said they just changed the coil for a miss fire. So today I figured I'd check my plugs. I could see one coil looked cleaner. I pulled that one first. Plug was about 1/2 turn loose. Checked gap. Was 028 and very clean looking. I assume this plug was also changed 5000 miles ago. Then I pulled other plugs. They have 30000 on them. Very squeaky on the way out and they looked darker. Gap at 032. I assume they are darker just because of the more miles?

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[Juben]

I'd assume your assumptions would be correct. The plugs with more miles will definitely exhibit more wear, e.g. darker, sooty, worn insulators and electrodes. Given the mileage gap of 25,000 miles, they'll, without question, look different. I usually change mine every 10k-15k miles depending on their condition.

Based on your pics, the 30k plugs do look a little worn, but nothing that'd cause concern, in my opinion. I'd definitely gap them to 0.028 like the newer plug and make sure they're all properly tightened.

 

[tw557]

Thanks I thought so. I did gap all at 028 and a dab of antisieze on each threads also. Thanks.

 

[Jcopin]

quick question. i just changed out my plugs with new motorcraft ones. for a stock car do Denso really make any difference?
Secondly, the old ones with 48k on them had a gap of about .035 for 3 of them. 1 was at .036.

is it normal for the gap to widen over time? I thought .030 was factory spec. the new ones were all .030. Should i make the new ones .028 for a stock EB? if so, why?

here is another one for the hell of it. are those little gap measuring "coins" sold at advance auto and such good? do they damage the tip of the plug since they're metal?

thanks

 

[Juben]

quick question. i just changed out my plugs with new motorcraft ones. for a stock car do Denso really make any difference?
Secondly, the old ones with 48k on them had a gap of about .035 for 3 of them. 1 was at .036.

is it normal for the gap to widen over time? I thought .030 was factory spec. the new ones were all .030. Should i make the new ones .028 for a stock EB? if so, why?

here is another one for the hell of it. are those little gap measuring "coins" sold at advance auto and such good? do they damage the tip of the plug since they're metal?

thanks

Densos are a great upgraded whether stock or modded. That gap is pretty large for an EcoBoost engine and will probably start to exhibit some spark blowout, if it hasn't already.

It's completely normal for spark plug gap to grow over time. That's why it's recommended to check them every so often. I check mine every 5k miles to ensure they're all within spec. For a stock engine or very mild mods, like intake and exhaust, I'd recommend 0.028. For tuned cars with heavier mods, I'd say to run them at 0.026. Ideally, you want to run the widest gap possible without detrimental effects to performance and 0.026-0.028 seems to be the sweet spot range. If I gap mine at 0.030, I get spark blowout something awful.

In regards to the coins, they're garbage and you'll stand a very good chance of messing the plugs up with one. They sell a feeler gauge style gap tool, and although it's a bit more expensive, it's well worth the few extra dollars.

 

[Jcopin]

Densos are a great upgraded whether stock or modded. That gap is pretty large for an EcoBoost engine and will probably start to exhibit some spark blowout, if it hasn't already.

It's completely normal for spark plug gap to grow over time. That's why it's recommended to check them every so often. I check mine every 5k miles to ensure they're all within spec. For a stock engine or very mild mods, like intake and exhaust, I'd recommend 0.028. For tuned cars with heavier mods, I'd say to run them at 0.026. Ideally, you want to run the widest gap possible without detrimental effects to performance and 0.026-0.028 seems to be the sweet spot range. If I gap mine at 0.030, I get spark blowout something awful.

In regards to the coins, they're garbage and you'll stand a very good chance of messing the plugs up with one. They sell a feeler gauge style gap tool, and although it's a bit more expensive, it's well worth the few extra dollars.

Is it a noticeable difference with the densos?

 

[Juben]

Is it a noticeable difference with the densos?

Unless your old plugs are shot and performing like crud, probably not. This is more of a supporting mod and maintenance practice. You won't feel it on the butt dyno unless the old ones were worn out.

 

[Jcopin]

Does gapping to .028 from .030 have any adverse effect on mpg? Curious why ford wouldn't gap that at the factory.

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