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Vehicle:

2000 Ford Windstar, 3.8L V6 engine, automatic transmission, 166,000 km, recently purchased, was brought to me for some torubleshooting and minor repairs

Symptoms:

  • Occasional hesitation
  • Check Engine Light on, code was "cylinder 5 misfire"

Troubleshooting done so far:

  • disassembled wiper blade cowl and removed wiper assembly to gain access

  • removed spark plug cables (resistance test not done yet)

  • removed spark plugs: #5 looks new except for some brownish colour, the other 5 are pink, all gaps are on the high side (high 50's, should be mid-50's)

Pictures Cylinder #1 Cylinder #2 Cylinder #3 Cylinder #4 Cylinder #5 Cylinder #6

Question:

  • What causes pink colours on spark plugs?
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4
  • @NumairAidroos - Even as a comment, I'm not sure what bearing your questions have in reference to what the OP is asking?
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Oct 6, 2017 at 12:20
  • 1
    The #5 plug (non-pink) looks much newer/cleaner. Does it look like this is a matching set of plugs? I'm surprised by what looks like rust and burnt oil on the other plugs in the thread area. I don't know if it's the pictures, but the #5 plug also looks like a longer plug (higher heat range). Are they all identical length from the seat surface to the hot end of the barrel?
    – Tim Nevins
    Oct 6, 2017 at 20:04
  • @TimNevins - It looks like a new plug in comparison to the other plugs. Looking at the exterior porcelain, you don't see the dirt ring (which would form below the boot), nor the dirt (oil?) in the threads, plus the metal still looks shiny (really shiny in comparison to the other five). I'd suggest #5 is fairly close to brand new.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Oct 7, 2017 at 0:09
  • @TimNevins I believe #5 was recently replaced by the previous owner to attempt to solve the cylinder 5 misfire. All plugs are the same length, the pink ones have rust and oil on them.
    – tlhIngan
    Oct 7, 2017 at 5:03

1 Answer 1

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I assume you already checked the heat range.

The pink color has a similarity to the "ferrocen" symptom. Ferrocen is an iron-containing anti-knock fuel additive. It causes red, electrical conductive, deposits on the spark plugs. There are cases documented where is was illegally used to increase the octane rating of cheap fuel (google "Firepower ferrocene spark plugs"). According to Bosch (sorry for the German reference) cleaning is futile, you must replace the plugs (and the fuel station?).

Perhaps you want to ask the owner if he uses some fuel additive or prefers a certain brand of "special" fuel at a station where it is spectacularly cheap?

Edit: I also found an additional reference from champion (first picture on the top left)

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3
  • The van was very recently purchased, I believe they are still on their 1st tank of fuel. This must have been from the previous owner.
    – tlhIngan
    Oct 6, 2017 at 16:08
  • While this is an awesome answer, it makes me wonder how one spark plug wouldn't have the pink discoloration? (EDIT: I think I answered this in my comment on the OP's question.)
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Oct 7, 2017 at 0:06
  • How how soon after the ferrocen reaction to our spark plug tips, do you rekon we swap them out?
    – Lawyer Aidroos
    Oct 31, 2017 at 6:21

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