only one black spark plug

[krawczuk]

ok about 2 mounts ago i blew the head gasket but befor that my passenger side last plug was always coming out black all fixed now but my spark plug keeps coming out black

its not oil on it its black carbon
what would cause this?

hi, could be low on compression, but my bet is non firing/ intermittent firing plug and or lead .. maybe even coil pack ???
mark k

 

[PaRaDoX]

flat black is un-burnt fuel ("carbon") check comp, if comps ok then check the dissy cap dissy cap ok swap another injector for this one and see if it still does it

 

[vn calais manual]

hi, could be low on compression, but my bet is non firing/ intermittent firing plug and or lead .. maybe even coil pack ???
mark k

his car is v8.

 

[HSV472]

well this week im going to buy new dissy cap rotor button and a new injector:bang:

and the comp is perfect
leads ,plugs are new but it was doing it befor i changed them anyway


could it be one of the valves
or
lifters on that cylinder?

 

[greenfoam]

Unlikely to be anything other than the injector if the compression is normal, I watch my plugs all the time and like I said I've replaced a few over the last couple of years that have gone bad. It may not seem a common problem but I bet it is. Just that no one else cares

 

[savage1987]

haha jason I don't even know how my compression is I've never had a check on either car.... maybe something i should look into

 

[pete30nz]

Hi people,

This is the condition of my 6 new spark plugs, it's a dry soot. The spark plugs have done less than 150km, It's on my vr v6. It has a new oxygen sensor.

I've had a read over a couple of posts and will swap to my spare injector rail to see if it improves. All new seals on my spare injectors for the vr v6.

Pete

 

[Immortality]

Or a dud spark plug or plug lead wasn't on properly or as I recently experienced, not torqued down properly.

IF the plug that came out wasn't all carbon-ed up it would suggest the problem lies with the new plug or something associated with it i.e a loose plug lead.

 

[pete30nz]

OK, so tomorrow I'll run the car, then pull a plug out and check if it's carboned up again. Today I made sure the plugs were tight when replacing them after a check and clean. I also replaced the coil packs 2nd hand as an elimination.
If they are re carboned, then check all lead connections are snug / tightly fitted.

Any other things to check?

Pete

 

[Immortality]

If the problem persists you may be looking at an injector issue. You could try swapping injectors around and see if the problem moves with the injector.