How Long Before Plug Change

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Jan 5, 2009 | 04:45 PM

boatnfish

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Mountain Pass

Joined: Dec 2006

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How Long Before Plug Change

Curious as to how long (years & miles) people have gone before changing plugs on a 5.4.

Why did you eventually change them, and what problems did you have?

Jan 5, 2009 | 05:04 PM

n5926g

Posting Guru

Joined: Oct 2008

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From: Hernando Ms

Under normal circumstances,Id say replace the plugs/wires at around 100,000 miles.Ive never personally had one go bad on my 97 4.2,but after the 100K mark,the gap will be eroded enough to at least require re-gapping.The wires are pretty much a no-brainer,as most wires will come apart when the plugs are changed.
Concerning time,id say(if youre engine stays relatively clean) 4-5 years on the wires.

I remember my 70 Mustang with the 302 required plugs about every 5000 miles or so,but THAT was a carberated engine.Todays fuel injected engines make plug changes almost non-existant.

Jan 5, 2009 | 05:08 PM

LxMan1

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Joined: Dec 2001

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From: Louisville,Ky.

I changed mine @ 70K and they were worn, but not real bad.

Jan 5, 2009 | 06:29 PM

galaxie641

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Joined: Nov 2006

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From: SE Wyoming

60K-70K. They are too easily screwed up and made to blow out if you leave them in too long and/or do not torque them properly. The ignition systems run so hot that it doesn't take much of a plug to fire the cylinder so it really comes down to replacing them as preventative maintenance for the blow out. Make sure to replace all the COP boots since you will be in there anyway.

Jan 5, 2009 | 10:16 PM

steve(ill)

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Joined: Jul 2005

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i bought my F150 with 120k miles. Had a miss by 130k miles. Changed out all the plugs. all were original and WIDE gaps. Book says 100k intervals, that sounds like a good point to me.

Jan 6, 2009 | 07:13 AM

mjunk1

Fleet Mechanic

Joined: May 2005

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From: Vale, NC

I'm thinking around 100k as the book says also. Wouldn't hurt to go a bit early, probably wouldn't hurt to be a bit late. If they are bad, you'll know it by the way it runs.

Jan 6, 2009 | 02:09 PM

tj90

Senior User

Joined: Sep 2006

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I changed mine at 100k and it was a mother getting them out from all the years of dirt and crud. Antifreeze crusted down the holes doesnt help either. I will replace at 50k intervals from now on, just to make the replacement easier on me in the future!