Spark Plugs - NGK Equal?

[tjanok]

I unfortunately dropped a plug and cracked the porcelain. Looks like our stock plugs are Motorcraft #SP542.
Pretty sure these have a heat range of "8". I know it was pretty standard to drop to one step colder on the 2.3 in the Mustang/RS. (Assuming a tune)

Anybody swapped to NGKs or similar, step colder or not? I can't find the SP542s locally, and unable to cross ref a NGK plug.

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[Scoops14]

I unfortunately dropped a plug and cracked the porcelain. Looks like our stock plugs are Motorcraft #SP542.
Pretty sure these have a heat range of "8". I know it was pretty standard to drop to one step colder on the 2.3 in the Mustang/RS. (Assuming a tune)

Anybody swapped to NGKs or similar, step colder or not? I can't find the SP542s locally, and unable to cross ref a NGK plug.

According to the owners manual they are SP-578 (page 320).

 

[_Ian_]

I unfortunately dropped a plug and cracked the porcelain. Looks like our stock plugs are Motorcraft #SP542.
Pretty sure these have a heat range of "8". I know it was pretty standard to drop to one step colder on the 2.3 in the Mustang/RS. (Assuming a tune)

Anybody swapped to NGKs or similar, step colder or not? I can't find the SP542s locally, and unable to cross ref a NGK plug.

Just went through this myself and couldn’t find an answer unfortunately, and only found plugs 2 steps colder that I didn’t want to go with. I was under the impression our factory plugs were SP578 though, you may be able to find them locally.

 

[tjanok]

Strange. My plugs are indeed SP542 I pulled out. I did have them replaced during a TSB awhile ago.
I wonder why they switched them out.

 

[Scoops14]

Just found this on 5 Star Tuning site:

https://5startuning.com/product/201...torcraft-iridium-spark-plugs-set-of-6-sp-578/

Part number SP- 542 has been superseded by Part number SP-578

 

[outdoorphotog]

I would stick with the recommended heat range unless you are making a lot more power and trying to fight detonation.

 

[NOVA_Ranger]

I'm running a 91/93 Tune and I'd like to go a step cooler when the time comes to change plugs. What are people going with for this?

 

[tjanok]

I'm running a 91/93 Tune and I'd like to go a step cooler when the time comes to change plugs. What are people going with for this?

It seems the NGK 6510 are still the choice, as with other EB engines. I ended up sourcing a pack of SP578s for now. But I do have a 5* tune I'd like to run eventually, and might might give the 6510s a shot. I had issues with early fouling on a step colder plug in my 3.5.

 

[HoosierT]

Any new info on this? Wanting to change my plugs since, according to other EB forums, running tuned (high boost) on these motors kills plugs in a hurry. I ordered some 578s since 542s are superseded and really hard to come by but not certain I want to put them in. They’re positively one step hotter than the 542s so I’m having a hard time pulling the trigger...

 

[MyLittleRanger19]

https://www.pandamotorworks.com/col...rworks-pre-gapped-ngk-step-colder-sparl-plugs

 

[HoosierT]

https://www.pandamotorworks.com/col...rworks-pre-gapped-ngk-step-colder-sparl-plugs

Nah, extensive research indicates that not only do these not have iridium in the straps (aka not double iridium like the motocraft), but they also don't perform as well according to testing by multiple EB tuners. Additionally, gapping the 6510's to .026 is going beyond the recommended allowable gapping from NGK. Ending up finding out that the 542s, being one step colder, were likely superseded due to emissions and replaced with a normal temp plug. As such, they moved these plugs to their ford performance line and changed the model number to Ford Performance M-12405-35T. I ordered three sets so I can keep some on hand and bought a nice gapper tool so I can gap them down to .026 as recommended for nearly any tuned EB. I'll report back how the truck runs after I get them put in tomorrow.

 

[HoosierT]

Okay, so I was assuming my truck had the sp542(one step colder plugs) based on other EB platforms and what @tjanok found above. However, my truck indeed had sp578 (CYFS12YPT) in it. Picture below, they don’t look great after 24.9k miles but 19k of those have been while running the 93 performance tune. I installed the sp542 one step colder plugs (ford performance part number above) and I can say with certainty that the truck runs and idles more smoothly. I’m glad I changed them out for sure.

 

[HoosierT]

Also, I did gap them down to .026 for the record.

 

[geophb]

Even stock the ecoboost eats plugs.

 

[HoosierT]

Even stock the ecoboost eats plugs.

So I've read, which is why I wanted to change them early and inspect. The stock plugs probably still have plenty of life based on the gapping, condition of electrode. and general cleanliness of the insulation. However, I felt that my truck wasn't really running all that great. I think the original richness of the Rev1 tune from 5Star coupled with a bad bout with bad gas on a road trip just contributed to some premature wear on them. Certainly running better now.

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