Misfire like no other

[SyntheticShield]

My immediate assumption would be over tightening of the plugs, but it looks weird. Like it (the ignition voltage) found pores in the ceramic and arced up the plug.

 

[MTXGTP]

i kno that the spark is going into the insulator instead of through the plug

 

[archemedes]

I have seen that a few times, and only with the AC plugs (when at the dealer we had a bunch of cars with that problem) not sure the cause of it other than possibly poor workmanship in Mexico (delco quality suffered after the sell off)

 

[Toasty]

looks like it started as just cracked porcelain, went worse from there....what you see as dark deposits is some form of residue (carbon?) from the spark funneling through the porcelain, the longer it goes this way, the more cracks develop

 

[MTXGTP]

yea Cause NGK makes the AC delco plugs.

 

[SyntheticShield]

So Im assuming that replacing these has fixed the misfire issue?

 

[IndeedSS]

yea Cause NGK makes the AC delco plugs.

You sure about that? I and many others run NGK w/o issues.

 

[IndeedSS]

Carbon tracking:

Carbon tracking leaves dark lines, possibly looking like cracks, permanently etched into the spark plug ceramic and rubber of the boot. Carbon tracking cannot be rubbed or cleaned off by any means.

Higher peak cylinder pressures require higher demand voltage for spark plug operation. Higher demand voltage increases the stress on the spark plug to spark plug boot dielectric interface, such that contamination and air gaps between the spark plug and boot can cause this interface to breakdown. A break in the dielectric interface can allow the spark to find a path to ground other than the center electrode. These paths or carbon tracks are etched into both the spark plug and the spark plug boot

I would pull the spark plugs out and look at them closely to see if there is any evidence of carbon tracking. To correct this condition, it is necessary to change both the spark plug wire and the spark plug at the same time on only the cylinder involved. Changing only the spark plug or only the spark plug wire will not prevent the carbon tracking from recurring. Carbon tracking will happen again in the same location much quicker if half of the track is still available. Recurrence of the same problem is likely in as little as 1,000 miles if the carbon track is not totally removed

 

[archemedes]

yea Cause NGK makes the AC delco plugs.

I have had some that were stamped champion on the metal part (lowest bidder maybe?)

 

[MTXGTP]

^^^ i would say so

i ordered some taylor wire and some autolites i hope this crap finaly quits.