SP542 Thread

[Spartan1]

I went ahead and did the swap form the SP 534 to the SP 542. The truck did seem maybe a little smoother although I changed the oil at the same time so who knows.

 

[OPT PRIME]

Today I romped on the truck off the line in 4A and during the shift from 3-4 I the engine cut power, CEL flashed and I limped along for the next mile until the condition cleared. Pulled codes at home: P0300, P0301 and P0304. Upon shutting down the truck in the garage I noticed water dripping form the exhaust, it has been pouring here for days. I presume when I shut the truck down I picked up a bit of moisture in the intercooler and it caused a general knock.

Will try the SP542 this week...

Frak!

 

[hammer73]

@Whipple Charged, et al,

FWIW I replaced my stock spark plugs for the SP542's, gapped at 025

With CAI and Whipple tune the car definitely to starts easier and idles smoother.
No science/measurement to the conclusion.. just observation.

 

[RaptorFlipper]

I concur. Starts easier and idles much smoother after switch.

 

[802Avalanche]

20K miles on OEM plugs. Whipple Stage 1 went on at about 6,700 miles. For the most part i have had very few issues. very infrequent rough idle. however, i have had a couple misfire codes. unsure whether those were caused by an argument between ACC and my right foot or something else. tech is working on plugs right now. #1 plug was gapped at about .027-.028 which is wider than the Whipple spec .025. Perhaps that alone could've been an issue. Anyway, opted to go with SP542 at .025" this time. So hopefully that makes things better, not worse.

 

[OPT PRIME]

Whipple Stage 1 with 23,000 miles, not driven easy. Recently started getting misfire codes and horrid stumbling issues with a flashing CEL. P0301 - P0306 and even a P0316!

My SP542s arrived today and I regapped them to .025, nothing changed. Once I got into a long hard pull in top of third you could hear audible misses and by fourth we were well into limp mode...

My friend asked about gas and as I glanced up at the 2/3 full gauge it hit me, it’s not 93. I topped off with 93 from Chevron and even added a bottle of VP octane booster (80 points per 10 gallons), hoping that will at least get me up 2 octane in the tank. She still stumbled a bit and gradually improved. It’s been raining hard and with rush hour I couldn’t open her up to check however I suspect it’s fine.

Take aways.

My OE plugs we fine at 23,000 miles, still right at .025” gap.

The truck runs exactly the same with the 542s.

If you have a tune and inadvertently swallow something under 91 octane problems won’t likely show up until above 5,000 revs and a few gears have passed by. I can’t say what the gas station actually had under the 93 label, 87, 89, etc...








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[OPT PRIME]

It was fuel. Still think stock plugs GTG, I’ll keep the new ones to stay hip.


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[K1llD4shN1n3]

Well earlier this year when I came across the SP542 recommendations I thought it sounded crazy. After reading this thread I ordered them lol

I have MPT 91PRX and I’m eager to see if it makes a difference. I have 30k miles now so should change them anyways.


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[K1llD4shN1n3]

Well I installed the new plugs this evening and I’m shocked how much of a difference it made.

I have the MPT 91PRX tune at the moment and the NGauge unit doesn’t hit as high of knock (in positive range) as it did.

The stock plugs were very hard to break loose. I used anti-seize for the SP542s so hopefully future replacement is easier. I gapped the SP542s at 0.028”

The stock plugs had a gaps ranging from 0.029 to 0.032.

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[K1llD4shN1n3]

Started the truck up this morning and it was noticeably more quiet with cold start and truck was certainly more smooth in acceleration. Temp this morning was 27 degrees.

I’m still shocked there is such a positive difference with these plugs


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