dean1484
dean1484 UberDork
6/21/13 3:47 p.m.

My Porsche has been running rough lately and since it ahs been a while sine I have changed the plugs I decided to swap them out for the new ones I have on the shelf. When I pulled the plugs they are all a little on the rich side (tan with a little bit of black) BUT there are also areas of red on the insulator. I have never seen red before. What does this mean. With a little Google Fu I found this.

High Speed Glazing that indicate combustion chamber temp have risen suddenly during hard acceleration, normal deposits melt to form a conductive coating, causing misfires.so change the plugs with colder range.

Is this true? I am actually wondering if I should be running a hotter plug so the deposits burn off during "normal" operation so when I get in to it there are no deposits to burn off and glaze the plugs.

Anyone got any ideas / opinions?

MadScientistMatt
MadScientistMatt UltraDork
6/21/13 3:49 p.m.

Some fuel additives will also leave a reddish coating.

PseudoSport
PseudoSport HalfDork
6/21/13 3:55 p.m.

I’ve seen this once on my old Jeep running NGK plugs. When compared to a stock Champion plug the NGKs looked hotter so I switched back and everything was normal after that.

What octane are you running?

GVX19
GVX19 Reader
6/21/13 4:06 p.m.

In reply to dean1484: Do they look like this?

I need a Photo to be of more help.

dean1484
dean1484 UberDork
6/21/13 4:15 p.m.
GVX19 wrote: In reply to dean1484: Do they look like this? I need a Photo to be of more help.

I just took some and will post them up in a while. thanks!!!

fasted58
fasted58 PowerDork
6/21/13 4:28 p.m.

Kinda dated but back in the day 104 Octane Booster used to do that. Haven't had the need to boost octane lately tho so I dunno what's out there.

Zomby Woof
Zomby Woof UberDork
6/21/13 5:51 p.m.
When I pulled the plugs they are all a little on the rich side (tan with a little bit of black)

Even if you did a proper throttle chop, that means nothing.

I don't think anybody (except the bike guys and they haven't got a clue) reads plugs for fueling anymore. Timing yes. Fueling, no.

Kenny_McCormic
Kenny_McCormic Dork
6/21/13 6:58 p.m.

Are these stock size plugs in a stock engine?

belteshazzar
belteshazzar UberDork
6/21/13 7:57 p.m.

my vote is for fuel additive, also.

dean1484
dean1484 UberDork
6/22/13 10:08 a.m.

The ignition has been changed from stock one to a ford EDIS based unit from a 93 Contour controlled by a MJLJr. Timing map is about the same over all just a little more up above 5500 rpm. The stock map dropes off over 5800 where as my map maintains timing so I can run it up to 6800 if I want. I have the soft rev limiter at 5.8K and hard limit at 6K for the street. Track is set to 6.5K and 6.8 K. The motor has a tic or two more compression but nothing "special" Rest of the motor is stock 1983 short block with 1989 cam. Motor has not been on track with these plugs and I have not hit the limiter on the street in more than a year.

Kenny_McCormic
Kenny_McCormic Dork
6/22/13 9:40 p.m.

Sounds like you should go a step colder then.

kb58
kb58 HalfDork
6/23/13 11:27 a.m.

Yeah... pictures.

We need more details... like brand of gas, octane, any additives you put in, what the car's being used for, and how long it takes to color the plugs

dean1484
dean1484 UberDork
6/23/13 10:20 p.m.

Photos as requested.

Two of the 4 the others were the same.

GVX19
GVX19 Reader
7/2/13 9:58 p.m.

I don't know why they have that tent to them. Check your fuel filter. If it is old and passing rust and trash from the tank to the eng. It my explain the tinting.

Knurled
Knurled UberDork
7/3/13 12:37 p.m.
MadScientistMatt wrote: Some fuel additives will also leave a reddish coating.

So do many leaded fuels.

dean1484
dean1484 UberDork
7/3/13 3:03 p.m.

Just noticed I did not choose the best background for the photos.

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