Changed out GM plugs 169,000 miles pics

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WobblyElvis

WobblyElvis

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Finally changed out the original plugs in my 2.2 Malibu at 169,000 miles. The factory spec gap was .042" but they had worn to between .065" to .095". This engines does not use coil on plug ignition, but uses one coil for every two plugs. One plug will fire from the centre electrode to the ground terminal and it's twin will fire from the ground back to the centre electrode. You can see how the centre electrode is eroded down on every second plug. I don't recommend waiting this long to change plugs.

Everybody loves pictures
 
I know its recommended to do them at 100k, which is when I did my grandparents 2001 Saturn L200 with the 2.2. The plugs in their car looked perfect when I changed them out. Interesting how the ones that fire the opposite direction were so much more worn out. I honestly don't remember what the coil situation was on their car, but would assume it is the same as yours.
 
The part number is the same for all plugs, but they are "double iridium", this means that both the centre and side electrode have an iridium tip. This way the plugs resist erosion regardless of which way they fire.

The engine doesn't really run any different although I have an occasional mis fire code that presented itself about a week before I changed these plugs. The code came and went a couple of times after changing the plugs so I can't say the plugs cured that problem. Engine runs very well.
 
That's why "dual platinum" and iridium plugs exist... :)

Metal ions are always removed from the "positive" electrode, so it will erode the fastest. When a single coil fires two plugs, one center electrode is "positive, the other is "negative" and the ground (threads) of both plugs are essentially "neutral."

Note also that a lot of engines that have two plugs per cylinder work this way and only have one COIL per cylinder which fires both plugs (eg. Gen-III Chrysler Hemi engines).
 
Good, big double ended coils.

COP have proven to be troublesome if you believe what your reading on Honda and Nissan forums. The Honda 1.5 COP go between the cast-in-head exhaust runners - talk about trouble just waiting in the shadows ...
 
Originally Posted By: slacktide_bitog
What did you replace them with? Did you use AC again, or did you switch brands like NGK?


I replaced them with AC delco plugs, as close as I could get to original. They seem to last.
 
This kind of system is called a "wasted spark" system because the plugs fire twice as often as they should--when one cylinder is sparking at the correct time at the top of the compression stroke, the other cylinder is sparking during the exhaust stroke. The late model Chrysler 3.7 (2009+ I believe) has an especially strange setup with COP for half the plugs and then short wires running to the other plugs. So it's like....a half COP engine and half not. My 2012 KK is like this and it threw me for a loop when I changed the plugs.

Also, some engines did indeed come with mixed part number spark plugs from the factory. The ford 4.0 sohc was a wasted spark engine and had "left" and "right" plugs from the factory--they were single plats but which part was plat was different between the two sides. But if I recall correctly the manual just called for the regular motorcraft double plat plugs for replacements. I'm not even sure you could get the factory plugs anywhere. Probably just a way of saving a tiny bit of money at the factory.
 
Last edited:
Originally Posted By: WobblyElvis

The engine doesn't really run any different although I have an occasional mis fire code that presented itself about a week before I changed these plugs. The code came and went a couple of times after changing the plugs so I can't say the plugs cured that problem. Engine runs very well.


This is what I argued here before. The spark in newer ignition systems is so hot the gap becomes less critical. It'll fire across a 0.1 gap just as easy as a .035 gap. I doubt I'll ever replace the plugs on my stuff.
 
Originally Posted By: WobblyElvis
Finally changed out the original plugs in my 2.2 Malibu at 169,000 miles. The factory spec gap was .042" but they had worn to between .065" to .095". This engines does not use coil on plug ignition, but uses one coil for every two plugs. One plug will fire from the centre electrode to the ground terminal and it's twin will fire from the ground back to the centre electrode. You can see how the centre electrode is eroded down on every second plug. I don't recommend waiting this long to change plugs.

Everybody loves pictures

How hard are the plugs to get out after being in use that long? I have 12 years on my 04 Camry V6, and I am a little concerned about taking plugs out of an aluminum head at 68,000 miles. I have read someplace that Denso plates the threads with tin to ease removal. Anyone know about that?
 
Originally Posted By: turtlevette
Originally Posted By: WobblyElvis

The engine doesn't really run any different although I have an occasional mis fire code that presented itself about a week before I changed these plugs. The code came and went a couple of times after changing the plugs so I can't say the plugs cured that problem. Engine runs very well.


This is what I argued here before. The spark in newer ignition systems is so hot the gap becomes less critical. It'll fire across a 0.1 gap just as easy as a .035 gap. I doubt I'll ever replace the plugs on my stuff.


I don't know about that. If I were to look at my example for a problem, It could be said I left the plugs in to long and the stress on the coils/ignition module has resulted in an intermittent misfire code. This code only appeared a week before I changed the plugs and it has come and gone a couple of times after I changed the plugs. Perhaps, had I changed the plugs a year ago, I would never have seen this code.

As it happens, the check engine light has been off for about 10 days, but It should have never been there.
 
Originally Posted By: HosteenJorje
Originally Posted By: WobblyElvis
Finally changed out the original plugs in my 2.2 Malibu at 169,000 miles. The factory spec gap was .042" but they had worn to between .065" to .095". This engines does not use coil on plug ignition, but uses one coil for every two plugs. One plug will fire from the centre electrode to the ground terminal and it's twin will fire from the ground back to the centre electrode. You can see how the centre electrode is eroded down on every second plug. I don't recommend waiting this long to change plugs.

Everybody loves pictures

How hard are the plugs to get out after being in use that long? I have 12 years on my 04 Camry V6, and I am a little concerned about taking plugs out of an aluminum head at 68,000 miles. I have read someplace that Denso plates the threads with tin to ease removal. Anyone know about that?


The plugs were easy to remove and came out clean. The new AC/Delco plugs come with an anti-seize coating already applied.
 
Originally Posted By: ksp7498
This kind of system is called a "wasted spark" system because the plugs fire twice as often as they should--when one cylinder is sparking at the correct time at the top of the compression stroke, the other cylinder is sparking during the exhaust stroke. The late model Chrysler 3.7 (2009+ I believe) has an especially strange setup with COP for half the plugs and then short wires running to the other plugs. So it's like....a half COP engine and half not. My 2012 KK is like this and it threw me for a loop when I changed the plugs.


The early production Gen III Hemi engines were similar, except they all had two plugs per cylinder. One plug had a coil on top and a wire leading off to one of the plugs on its 'paired' cylinder, which had a coil on its other plug and a wire leading back to the second plug on the first cylinder. That way if you lost a coil, ALL cylinders would still have at least one working plug and the catcons wouldn't get lunched quite so fast. They stopped on later Hemis and just fire both plugs of each cylinder with a single coil that mounts atop the two plugs, so I guess the extra complexity wasn't justified by a little extra catcon protection. No reason for doing it other than cost-savings on the 3.7, though.

Originally Posted By: ksp7498
Also, some engines did indeed come with mixed part number spark plugs from the factory. The ford 4.0 sohc was a wasted spark engine and had "left" and "right" plugs from the factory--they were single plats but which part was plat was different between the two sides. But if I recall correctly the manual just called for the regular motorcraft double plat plugs for replacements. I'm not even sure you could get the factory plugs anywhere. Probably just a way of saving a tiny bit of money at the factory.


The Chrysler 4.7 from 2008 up has two different TYPE plugs with different change intervals, not just single- vs double-plat. The intake-side plugs are all standard copper with a 30k change interval, and are mounted directly under the coil. The exhaust-side plugs are a different thread length and are double-plat with a 100k change interval since they're so much harder to get to. They're fired by the same coil as the intake-side plug, with a short ignition wire that crosses over the valve cover.
 
Originally Posted By: WobblyElvis
Finally changed out the original plugs in my 2.2 Malibu at 169,000 miles. The factory spec gap was .042" but they had worn to between .065" to .095". This engines does not use coil on plug ignition, but uses one coil for every two plugs. One plug will fire from the centre electrode to the ground terminal and it's twin will fire from the ground back to the centre electrode. You can see how the centre electrode is eroded down on every second plug. I don't recommend waiting this long to change plugs.

Everybody loves pictures



Looks like you should have rotated your plugs at the 85k mile mark.
wink.gif


BC.
 
I can get pics sometime later upon request.

A 2.2 I started driving about a year ago. I pulled 981s like you, but at 134117 miles. Replaced with 105s. On a 12/05 2006 Cobalt, so 10 years.

Car ran better and smoother, but still acts like it want to die sometimes, but the computer compensates, from what I know, so rpms drop below idle then just back over idle.....is this what a stepper motor does?


Still have an orange engine light on, but she runs (and can haul)!


4 speed automatic.........the very first automatic I like. A 88 coupe deville had a trans I did not hate.....so two automatic in my lifetime I could live with.. Still, manual strong!
 
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