Spark Plug Question

I just changed the plugs and wires in my daughters 2003 Sonata V6. It was
pretty easy because I used an illustrated how to guide that I found in an
Santa Fe forum. I even managed to replace the dreaded back center (plenum)
brace bolt that most people suggested to leave off because it was so
difficult. Its not too hard if you mark the plenum where the bolt is before
you remove it. I was shocked at the appearance of the back three plugs
(1-3-5). They were worn down to the nub, I measured the gap and they were
..075-.080. The front three were around .045. The car has 70,000 miles on
it was running great with no problems. I would have thought that the CEL
would have came on with a miss-fire they were so bad. Has anyone seen this
before? Is it indicative of some problem? Is the back bank running that
much hotter? The only difference I see is that the wires running to the
back bank are much longer that the front ones. And before someone asks the
question - no, the front plugs have never been changed, the car has been in
the family since new.

 

Is this a Canadian Model? I ask because I own a Canadian 2007 Sonata (built
in USA) and I had an irregular idle speed that would only happen on a cold
morning.
I reported this to my local dealership, they plug in the code scanner, but
did not get anything. So, with my knowledge, I requested that they check all
6 spark plugs for proper gap.
They wanted to charge me for that request, SO, I did it myself.
Spark plug #3 and #5 were at around .060". After adjusting them, my
irregular idle on a cold morning disapear. Problem fixed in one Saturday
afternoon in my shop.
The car now has 42000Km +, this little "tune-up" was done when the car had
9000Km. There was no CEL. I do not think that the rear banck should be
running hotter than the front one.
I have "coil over plug" on my Sonata, I think that the wires you are talking
about are the 12 volts wires to the coils!?!

Hope this helps you out.

TheIceAge05
My knowledge bank is at www.hyundai-forums.com
My shop manual is at www.hmaservice.com
My own shop is at www.cfbhalifaxautoclub.googlepages.com/home

 

Is this a Canadian Model?<
Nope, US model.

about are the 12 volts wires to the coils!?!<
Nope, I was talking about the Hi-voltage wires from the coil to the plugs,
the coil packs sits up front beside the front bank.

 

What you describe is what I typically see. Here's why I think it occurs:

Your car has what's called a waste-spark system. It fires two cylinder
at a time (1-4, 2-5, or 3-6) by firing through plug wire #1 (or #3, or #5
into the engine block and back to the coil through plug wire #4 (or #6, o
#2), completing the circuit.

I'm guessing the fuel management system fires #1 with the same polarity a
#4. I.e., I'm suggesting that the spark always goes from the cente
electrode to the ground electrode on one bank, and from the groun
electrode to the center on the other bank, no matter which cylinder is o
compression.

I'm also reasoning that the direction of the spark causes one electrode t
absorb most of the wear and the other to absorb little.


If you go back and look at the plugs again, I think you'll see that th
bank with the most wear has worn the center electrode, and the bank wit
the least wear has worn the ground electrode.

As for being surprised there was no misfire, I'm not. Most newer vehicl
ignition systems will make a spark in excess of one inch.

 

And I bet you get reminded when you forget it. ;-)

Amazing how HV will find a way to ground.