1999 GMC Sierra Spark plug covers

Tiny
GWATS1957
  • MEMBER
  • 1999 GMC SIERRA
  • V8
  • 2WD
  • AUTOMATIC
  • 179,000 MILES
Each of my spark plugs has a metal sleeve over the plug wire near the engine block. What is this for?
Sunday, March 7th, 2010 AT 8:05 AM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
They reduce radio frequency interference (RFI) from interfering with the multitude of computers. The magnetically-induced voltages can be greater than some of the tiny signal voltages coming from the sensors and the computers will think the various spikes are sensor problems.

Caradiodoc
Was this
answer
helpful?
Yes
No
Sunday, March 7th, 2010 AT 11:35 AM

Please login or register to post a reply.

Sponsored links