SP542 Thread

[FordPerf Addict]

And what’s the stock gap.. how could ford get this wrong on a stock truck?


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[Badgertits]

Anyone getting benefits with these on stock tunes ?


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Yes. I think I already posted. I was getting some knock/pinging on occasion depending on conditions & also sometimes experienced “stuttering” @ WOT acceleration, not like a drop off in power but like subtle sputtering/choppy acceleration as power built especially in upper ranges.

These plugs fixed that immediately- idles smoother too. Worth the $65 spent easily.

 

[FordPerf Addict]

Yes. I think I already posted. I was getting some knock/pinging on occasion depending on conditions & also sometimes experienced “stuttering” @ WOT acceleration, not like a drop off in power but like subtle sputtering/choppy acceleration as power built especially in upper ranges.

These plugs fixed that immediately- idles smoother too. Worth the $65 spent easily.

I think I’m starting to notice that... I feel it happens because it’s a Cold motor and 89 fuel tho, I’ll have to pay more attention


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[New Nick at JDM]

I’m so confused. Is the stock plug a 550?

SP-550 is stock on certain build dates

 

[Badgertits]

I think I’m starting to notice that... I feel it happens because it’s a Cold motor and 89 fuel tho, I’ll have to pay more attention


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Oh hell yeah these engines HATE low octane. Haven’t been putting anything but 93 in mine once I burnt through the dealers fuel....

 

[FordPerf Addict]

Oh hell yeah these engines HATE low octane. Haven’t been putting anything but 93 in mine once I burnt through the dealers fuel....

I’m mostly highway cruising and pretty easy on it, But when i offroad or were to tow I always throw prem in. In the summer I didn’t notice any of the hesitation tho


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[titanjc]

SP-550 is stock on certain build dates

What build dates? And what is the other stock plug(s)?

 

[New Nick at JDM]

What build dates? And what is the other stock plug(s)?

I am not 100% sure on build dates but I know certain 2018's have them.
I've had a few customers we sent 550's to, only to note that the plugs installed are in fact 550's
I think it was 534's that were in these trucks in the beginning, but again I am not 100% sure. Also SP-550's are no longer factory as well. I think currently the SP-580's are factory?

It gets confusing as it seems some of the spark plug coding in the complete part numbers from Ford is not commercially available to the public.

For example, the SP-542 identifies as CYFS-092-YPT and the SP-578 (the now debunked 542 replacement as it is not identical) is CYFS-12-YPT

The first and sometimes second number (09) as with the SP-542 and (1) with the SP-578 is the heat range of the plug.
0 in front of the 9 with the SP-542 denotes "extremely cold." The 1 with the SP-578 designates "cold"
The last number (2) is the tip design, and in both cases is an extended tip.

The SP-550 identifies as CYFS-12Y-PCT, but looking at the ford spark plug information available to the public it may be out dated.

PCT broken down individually is P- Standard Platinum electrode, C- Copper core electrode, T- ???

Ford claims the 550 is an iridium plug, so this may be another factor in the mix.

When we decided on Spark Plug selection, we first tried the NGK-6510's with poor results.

The SP-550's we tried next had no detonation and we have ran with them since with zero issues.

 

[Dachuri]

I just got around to changing my original OEM plugs to M1240535T, Ford Performance’s part number for the colder SP542 which is now hard to find.

I ordered my plugs from Steeda, since they were the lowest delivered price at the time. They came out of the box gapped between .025 and .027. I gapped all as close to .028 as I could.

The OEM plugs that came out of my April 2017 build look to be the SP550 if New Nick at JDM’s info above is correct since the part number on the plug CYFS12YPCT. After 21,200 miles they all came out evenly gapped, at .028 surprisingly since I believe the manual states .031.

 

[NASSTY]

I just got around to changing my original OEM plugs to M1240535T, Ford Performance’s part number for the colder SP542 which is now hard to find.

I ordered my plugs from Steeda, since they were the lowest delivered price at the time. They came out of the box gapped between .025 and .027. I gapped all as close to .028 as I could.

The OEM plugs that came out of my April 2017 build look to be the SP550 if New Nick at JDM’s info above is correct since the part number on the plug CYFS12YPCT. After 21,200 miles they all came out evenly gapped, at .028 surprisingly since I believe the manual states .031.

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The original plugs on my early build 2017 were gapped @ .028 I checked them when my truck was fairly new. I replaced them around 20K miles with SP550's and they came pre-gapped @ .028