We have tons of Ford 3-valve Triton trucks in our fleet.
The replacement interval for them is 60K
And believe me, around 60K, the trucks can’t get out of their own way, because they’re screaming for new plugs. They have extreme difficulty keeping up with traffic
And most of the time, there is no check engine light on, no stored misfire codes. But there is something else . . . lots of activity on the misfire counter. Not enough to generate a light or a code, but enough to let you know what the problem is
I’m specifically talking about model years 2004-2008 only
I have to partially disagree about the idea that if the check engine light isn’t on, and there is no fault code, that your plugs must be fine
That may be true a lot of the time, but not always
“As long as the Check Engine light doesn’t come on with a misfire code, the plugs are fine.”
Not sure I agree with you on that one, @Tester . At the very least, you’re making the COPs work harder than they have to, increasing failure probability.
Every set of 100,000 mile plugs I have had have looked slightly worn but otherwise fine when pulled at 100,000 miles. Gaps were always within spec and none of them were ever stuck in the engine. I used to pull them every 30,000 miles to check them but got tired of wasting my time as the plugs always looked fine and it was a huge pain in the you-know-what.
Most o2 issues can be traced to exhaust leaks actually…or at least thats what I have found to be the case. Its either that or they flat out die… Sometimes on VW/Audi’s a cracked PCV system will post an o2 code…VW/Audi have a nasty habit of using brittle hard plastic hoses for their PCV system…they are a mess. Replacements/Upgrades are available in the aftermarket to correct this issue
Sparkplug electrodes erode gradually. As they do so, the gap through which the arc must travel grows. The arc concentration drops, the energy becomes more diffuse, and the arc temperature must therefore drop with it. This IMHO has to affect the ignition and the flame propagation.
In addition, perfectly normal ash buildup must IMHO adversely affect the arc even if it’s insignificant enough to cause the chronic misfires that trip a fault code.
My feeling is that an engine with old plugs may continue to run without misfire, but it doesn’t follow that it’s operating at optimum. As a previous poster mentioned, I too have noticed a performance difference when replacing old plugs even when there was no CEL present. I replace plugs every year or two whether I need it of not, and I believe the practice will contribute to a cleaner burning engine and resulting longevity… probably of the cat converter as well as the engine.
While I realize how extremely hard iridium is (8X harder than platinum), and I realize that erosion of the discharging electrode is definitely slower with iridium, I remain NOT and advocate of 100,000 spark plug changes. But, to each his own. If that’s what the manufacturer recommends and the owner follows that recommendation, he/she should be applauded for following the recommendations and not criticized for not replacing plugs sooner.
My personal observations with oxygen sensors . . .
Most of the reasons I’ve replaced were because of the heater circuit. Check engine light on, with a code for the heater circuit. Verified power and ground. No current draw, because heater circuit is dead. End of diagnosis. New sensor has correct current draw. Simple
I have also replaced a few because they were lazy, and the code pretty much spelled it out. No exhaust leaks. I know, because I verified with a smoke machine. The lazy oxygen sensors were always very old. Just a few weeks ago, I replaced an original, 17 year old sensor. The new sensor switched very rapidly, compared to the old
And then there the few that got replaced due to physical damage. Driver snagged the wires on something. Rodent damage, etc.
I’m not getting into biased and/or skewed sensors. I’ll let somebody else do that
Something interesting I learned recently about O2 sensors, they can be damaged by contamination getting on the outside of the sensor too. It’s not just that they are sensitive to contamination on the probe-looking part inside, the part in the exhaust stream. The reason is that for the O2 sensor to work, it sort of has to be able to breath in fresh air from the outside. I don’t know why this is needed, but to allow for needed breathing, O2 sensors have tiny ports or holes in them, inside to outside, that allow fresh air in the engine compartment to penetrate into the working part that lays in the exhaust stream. If those tiny holes get plugged up, the sensor won’t work.
I’m fully on board with mountainbike’s comments about spark plugs.
Regarding the seizure of plugs in heads consider the last time I changed plugs in my daughter’s 4.0 Mustang.
Those plugs had been installed by per the usual with a palm size 3/8" stubby ratchet. The tapered seat plugs were run down until they hit and then just bumped a bit to snug them.
On one Sunday afternoon while she was visiting I decided to pop the easiest one out (they’re all easy) and it was looking a little funky on the center electrode porcelain so I put a new set of plugs in. Three of them were refusing to come out even with a long 1/2" breakover. What was normally a 15 minute job turned into 2+ hours with me praying, “Oh God, please no heli-coils on the Sabbath…” although it was phrased more crudely than that.
I luckily managed to wrestle all of them out without thread damage and just to be sure I ran a thread chaser through every hole. Now the rest of the story.
Those plugs had anti-seize on them, were only snugged to begin with, and had only been in place in those aluminum heads for about 35k miles.
Your story just reinforces my belief and policy that spark plugs are to be installed with no anti-seize. It doesn’t help anything, and it can only hurt.
They were Autolites. The only plugs I use in family cars is Autolite, Bosch, or NGK now and then when they have them in stock.
If anti-seize was the cause of the frozen plugs then all 6 should have been stuck. I suspect it has more to do with cooling variations in the engine block and cylinder head rather than the anti-seize.
That’s just theory though.
I’m under the assumption that Autolite makes/made some of the plugs for Motorcraf . . . ?
Maybe, but that doesn’t mean anything. The same company that makes the Corvette made the Citation.
I would have used Motorcraft plugs in the Mustang. Looking at the threads I think the Motorcrafts are plated or coated so no anti-seize is needed. But according to ok4450 the Autolites had anti-seize and it didn’t help anything. But then I only ever replace spark plugs with the same brand that it came from the factory with.
The only time I will ever consider using anti-seize on a spark plug is if the engine came from the factory that way.
I don’t know who makes Motorcraft spark plugs, but I know it’s not Autolite, since Autolite doesn’t make their own plugs. I think they are a subsidiary of Allied-Signal or Honeywell or the same company that owns Fram or something like that.
I think of Motorcraft as far and away a better spark plug than Autolite. If anything, I would guess that the spark plugs that aren’t good enough to be labeled Motorcraft are then turned into Autolite.
A few weeks ago, I needed 1 single plug for a 3-valve Triton engine. I literally dropped a newMotorcraft plug, and I needed a plug right away. Having Ford deliver would have taken too long, unfortunatel
We headed over to our local NAPA, which is extremely close. We got an autolite plug, which looked 100% identical to the motorcraft plug. There are other brands out there, that look different, but this one looked identical
I don’t know anymore who makes what. I went to a seminar a few years ago given by the local AC Delco wholesaler, and the technical instructor really knew his stuff. And even he admitted that the only thing AC Delco makes is cardboard boxes in which to out the parts that are made everywhere by everyone.
That being said, I do believe that Motorcraft, Delco, Mopar, Denso, whatever parts, including spark plugs, are usually better quality than the aftermarket brands.
I don't know who makes Motorcraft spark plugs, but I know it's not Autolite, since Autolite doesn't make their own plugs. I think they are a subsidiary of Allied-Signal or Honeywell or the same company that owns Fram or something like that.
Yes they do. So what they’re owned by Allied Signal. Fram is also owned by Allied Signal…Does that mean that Fram doesn’t make filters. Autolite was making plugs long before Allied Signal bought them out.
Theres been so much consolidation in the industry it is hard to know who builds what anymore.
AC Delco was GM’s aftermarket parts division the sourced parts from GM’s own divisions, the real “Delco’s” and Fisher Guide, Inland, Chevrolet Axle as well as GM oe sources for their cars. As the closed or sold off or bankrupt those divisions or sources, they became a “box house” that simply put any suppliers part into an AC Delco box. Same for Motorcraft with Ford’s parts divisions that later became Visteon. And also later traveled the same fateful road of bankruptcy and sale. Mopar was probably the same but with fewer Chrysler-built parts because they just didn’t build as much themselves.
Federal Mogul has been through bankruptcy at least once, Dana as well. Kelsey-Hayes and Teves were bought out by Contenental, TRW took over Delphi’s Saginaw Steering Gear and has just been been acquired by ZF, Boge bought by Sachs, and then ZF took the whole lot. The brands remain be the actual parent companies are far fewer.
