Question on Spark Plugs for 2019 5.0

[jcttraveler]

My 2019 Mustang GT convertible has nearly 90K. I have some time, so wanted to change the plugs. Was also thinking of going with a cooler plug than I was already running because for nearly the entire time I've owned the car, it has suffered from pre-ignition (trips to the dealer, including ride alongs returned the verdict: "it's normal.")

Anyway, I pulled an existing plug. Decoding the number CYFS092FT I think it is a SP551. My manual calls for SP548 (CYFS12F1), but current searches say to run SP589 (CYFS12YT6).

I tried to dig into the details of each plug the 551 and 548 are obsolete. It seems they were heat rated at 7. From what I can tell, the 589 is a step cooler at 6, so should be what I was looking for all along. Can anyone confirm? Has anyone else experienced chronic pinging with OEM plugs? Thanks

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[ralph7]

I'm surprised the computer didn't take care of the pinging, even if you are running cheap gas.

 

[Optimum Performance]

SP548 >> SP548X You do want to run the SP589, that change happened when DI was added in 2018.

General Buyers Guide from our site. I say general because Ford likes to change things randomly.


Buyers Guide:



2011-2017 5.0 Coyote - SP548 (Platinum)

2018-2024 5.0 Coyote - SP589 (Platinum)

(also fits 2011-2017 3.7 V6)

2015-2019 5.2 Voodoo GT350 - SP548 (Platinum) OR...

2016-2020 5.2 Voodoo GT350 - SP590 (Iridium)

2020-2022 5.2 Predator GT500 - SP581 (Iridium)

 

[Optimum Performance]

If you are having pre-ignition issues, I have to ask exactly what oil are you using. You need to use an oil rated for LSPI.

 

[Optimum Performance]

SP551 >> SP589

 

[robvas]

You don't need a colder plug than stock on an NA cart

 

[jcttraveler]

If you are having pre-ignition issues, I have to ask exactly what oil are you using. You need to use an oil rated for LSPI.

I don't know which specific oil has been used because I don't change my own oil. I ask for 5w-30 synthetic. I keep a jug of Motorcraft oil around for the rare times I need to top off. I'll be more specific next time.

 

[Craig Brown]

As far as plugs go, I just changed my plugs and used NGK 6509. (normal heat range) I have a 2015 GT pp car N/A with mods like LTH catted, MBRP race cat back exhaust, CAI, 2018 Intake manifold, Auto Mafia performance tune. You do not need cooler plugs for the N/A cars. Normally I would have gone with the Motor craft plugs, the research I did showed the NGK to be a better plug. I also changed coils and I did go Motor craft. They changed the number for those too. It is DG-542 now. When I changed the plugs, the color was a nice golden brown, I also checked the gap of the old plugs and found that to be at .042 to .052. I only have 35 K miles on this car, so the plugs are factory set. Before changing plugs, I would get a random misfire code after running the car hard and at higher speeds. Again, doing some research, I learned the cause was a condition called (blow out) when the power in the combustion chamber would temporarily blow the spark away from the plug and the computer would detect the momentary misfire. Note, the car never ran rough. Anyway, when I gapped these plugs, I set them at .035 and that has cured the issue. Something to consider.

 

[Dana Pants]

I knocked down the plug gap a bit and a lot of roughness went away with the OE plugs… whatever they are.

 

[SCP440]

I fitted a set of NGK Ruthenium 12 months ago, better throttle response and marginally better fuel consumption.

 

[Weyland-Yutani]

Has anyone else experienced chronic pinging with OEM plugs? Thanks

Yes, and it's maddening. It's one of a few reasons I'm in the process of trading the car.

 

[Optimum Performance]

General question for everyone: What Octane fuel do you use? Have you ever run injector cleaner through a tank full of fuel?

 

[BullittBoy]

General question for everyone: What Octane fuel do you use? Have you ever run injector cleaner through a tank full of fuel?

I run 93 but my car is tuned with headers/H pipe and active exhaust and it is a NA Bullitt. I run a bottle of Amsoil fuel system cleaner at least once a year because I can't always get top tier gas, but I try too-

 

[Weyland-Yutani]

General question for everyone: What Octane fuel do you use? Have you ever run injector cleaner through a tank full of fuel?

93 Eagle Blood. Always.

Cleaners have been Chevron or whatever they use at Ford dealer shops.

 

[Optimum Performance]

93 Eagle Blood. Always.

Cleaners have been Chevron or whatever they use at Ford dealer shops.

Ford uses BG 44K

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