Toadster
FRF Addict
They kept stock plugs for me @.027 gap, They don't recommend colder plugs but I think due to emissions,etc
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SP542 Thread
- Thread starter Guy
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They kept stock plugs for me @.027 gap, They don't recommend colder plugs but I think due to emissions,etc
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I’d like to know if there is more to this than just a colder heat range.
Is there something different about the plug? Different resistance? Different spark geometry based on the strap design?
I just don’t get why one heat range colder will make this kind of difference.
Where is Fordza 1? Maybe you know. It’s a chance to wow me.
LOL I just saw this today. You have peaked my interest because I don't think you would make such a claim if not absolutely convinced.
Initially I don't have an actual reason why these particular spark plugs seem to make such a noticeable difference. That said, a spark plug is a pretty simple component, but plays a huge role in how any particular engine will perform. The center electrode and ground terminal design can make a significant difference in how the plug performs in certain circumstances.
The smaller diameter the center electrode the better for a more powerful spark ie the iridium versions being the most widespread for performance and longevity. The ground terminal is simply that, the ground point, so it just needs to be there and be sharp-edged at the tip and along the sides near the center electrode. The spark will easily jump from the tiny tip center electrode to one of the sharp edges of the ground electrode.
The one thing that will make a difference in the actual energy released at the spark is the resistance of the spark plug AND the spark plug wire/cable. The higher the resistance, the higher the voltage available at the center electrode. The higher resistance of the plug/wire makes for a huge spark, but taxes the coil heavily, hence the move to individual coil-on-plug designs.
My "GUESS" is that the OEM plugs/wires are spec'd for a relatively lower overall resistance and the SP542s have a higher resistance that results in a "hotter" spark, but a lower heat range because it has a shorter insulator to account for the extra heat with the shorter path to the head for cooling. I haven't researched the specifications on the oem plugs or the SP542 Motorcraft to be absolutely sure, but it sounds like something that needs to be done...
All said, I have zero running issues with my 2018 with the MPT 93PRX tune, but I will certainly buy a set of these (in)famous(?) Motorcraft SP542 plugs and see what all the noise is about!
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k-rub
Full Access Member
I put the SP542 plugs in yesterday and my truck has 22k miles. They came gapped at .026 so I left that gap. I was pretty surprised at my stock plugs. Looks like I've been running rich.
I agree with all of Guy's thoughts about these plugs. The truck starts, drives, idles, and accelerates much smoother than before. I am very impressed. At the same time another set of stock plugs would have helped too.
On a side note, I've been experiencing a rattle on startup. It lasts 10 seconds or so. The dealership diagnosed it as cam phaser rattle. The parts are on order and I'm supposed to drop it off Monday to get the work done.
Here's the weird thing. After putting in the new plugs the rattle is completely gone. Not a hint of a rattle. I still have to do some more driving to see if it comes back. But at this point I am completely baffled.
I agree with all of Guy's thoughts about these plugs. The truck starts, drives, idles, and accelerates much smoother than before. I am very impressed. At the same time another set of stock plugs would have helped too.
On a side note, I've been experiencing a rattle on startup. It lasts 10 seconds or so. The dealership diagnosed it as cam phaser rattle. The parts are on order and I'm supposed to drop it off Monday to get the work done.
Here's the weird thing. After putting in the new plugs the rattle is completely gone. Not a hint of a rattle. I still have to do some more driving to see if it comes back. But at this point I am completely baffled.
Did you disconnect the battery when you changed the plugs? Everything re-sets I believe.
k-rub
Full Access Member
Yeah I disconnected it. Are you thinking something in the programming changed and it has to relearn?
I was thinking waste gate but who knows.
https://www.f150forum.com/f118/2017-f150-3-5-ecoboost-strange-noises-399724/
On the video #14 if you click on it then watch it on youtube and look at the comments or just click below. This dude replaced the whole engine and it was still there. He then updated the PCM and it went away. He is probably on this forum.
https://www.youtube.com/watch?time_continue=25&v=Ix24_X8Vf7I
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k-rub
Full Access Member
Yeah that was MJSlasherAdmin. I got the PCM/TCM flash update. It got rid of a rattle in valve cover area. This other rattle sounded like it was coming from the bottom of the motor and out of the wheel well.
Maybe the combo of new plugs and the battery reset did something. I dunno. I'm super happy how it's running now though.
Maybe the combo of new plugs and the battery reset did something. I dunno. I'm super happy how it's running now though.
Well, I have a set, but haven’t installed them yet. I measured the resistance in them from firing tip to lead end to compare to the oem plugs. Haven’t measured the oems yet, but the SP542s range from 4.3 to 5.2 K-ohms. They’re iridium tipped on the center and the ground electrode.
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