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How do these plugs look?

879 views 17 replies 10 participants last post by  JDOGG  
#1 ·
I had to pull my blower off today to remove my J&S so i figured I would take a peek at my plugs. The numbers represent what cylinder they came out of, I only pulled 3. From the looks of it the boot on cylinder one got some water in it hence the corrosion. The plugs 1 & 3 look good but not2, I don't understand why the front bank would burn differently than the rear.


By mitchg53



By mitchg53
 
#4 ·
they look decent but they shouldn't be black like that... lots of carbon... perhaps too rich? Otherwise they look fine... they are suppose to be white with slight browning.
 
#5 · (Edited)
I thought that the plugs were supposed to be white to grayish color.

White is lean and black is rich, no? I know my tune is rich but I don't understand why the front bank looks differnt than the rear bank.

they have between 5-10K miles on them, I would have to look in my log for the exact mileage.
 
#6 ·
maybe your somehow getting more fuel into that cylinder?

Try pulling the plug next to the front one?
 
#7 ·
Yeah, I think I will take a look at it tomorrow while I still have the blower off. I am in the process of getting the engine bay cleaned for HIN in april, the 3000gt will be getting driven a lot until then.
 
#11 ·
It's funny you mention that. One of them wasn't that tight and I know I torqued them down like it should be.

HEy Mitch just for giggles can you get someone to flow the injectors out there for ya while you've got the intake off? Kind of a CYA thing more than anything else and as far as #2 plug that's not that bad it could be just an injector that flows jus a little more than the others:3_winkthu
Not near me. I know of a few companies on the web that I can get them to but i'm not really trying to do that. CYA?? You lost me.
 
#9 ·
Looks like that cylinder may be running a little rich. Carbon fouling will present as- dry, black, and sooty deposits on the plug.

Perhaps you have a faulty injector that is sticking open longer than it should be.
 
#10 ·
HEy Mitch just for giggles can you get someone to flow the injectors out there for ya while you've got the intake off? Kind of a CYA thing more than anything else and as far as #2 plug that's not that bad it could be just an injector that flows jus a little more than the others:3_winkthu
 
#12 ·
They seems to be in perfect range, even on 4cil F/I engines is almost impossible to have all the plugs at same "color/range".

If they look like this....



Then you have a problem w/ injector or something else
 
#14 ·
i'd say 3 and 2 look closer to each other than 3 and 2. that being said it's impossible to tell if your lean or rich without the following.
A) you need to replace your plugs with new ones
B) you need to do a couple full throttle runs and then shut the motor down IMMEDIATLY... absolutely right after you finish the run... limp it to the side of the road and check the plugs.
C) your looking for a small ring of deposits where the insulator meets the threaded body of the plug which cant be seen from these photo's.
Basicly from looking at your plugs you can tell that your idle is a smidgen rich but good... and they'res no detonation... that's about all these plugs tell ya.
 
#17 · (Edited)
Yeah, my maf took a dump on me and I noticed when I went WOT and the a/f hit 30 on my wideband. Thank got I have the built motor and the J&S otherwise whe would have popped. I did that 2 more times durring my test to see if the fault light was coming on on the mafterburner. I don't think that the cylider 2 plug would look like that fom just a few lean WOT pulls for just a second. Thoughts on replacing the plugs?

I just pulled the other three plugs real fast and they all look identical to 1 & 3, i wonder if my #2 injector is running a little on the rich side of things.
 
#18 ·
A) injector 2 is sticking open or just outflowing the others or cannot completely close due to some sort of manufacturer's defect or contamination.
Run some injector cleaner thru and see if the condition improves.

B) you're getting less air to cylinder # 2. I'd be tempted to rent a cylinder compression checker and see if that cylinder's sealing up to par with the rest.
perhaps a leaky valve or leaky rings? you may have overheated and slightly bent an exhaust valve on one of them 30:1 A/F ratio runs.