spark plugs

[Mercurios2011]

Hi there fellow enthusiast

So today i have a simple question for yall..

Which spark plug (brand,price range and material ) would you guys recommend ?
Now ,now I,m not talking heat range . The car puts out extra 17-20HP or 18% with current re map.( have yet to actually calculate that accordingly lol)
how ever here suddenly i went from 40 mpg to 37.9 mpg , haven't done anything different to the car or the way i drive ,other
than fixing the massive hole the muffler(J2 Engineering) had by replacing it with a Magnaflow one(so much quieter than i remember them to be).

These plugs are but a year old , Original OEMs Ford Motorcrafts (iridium) while I'm fully aware that when gas goes up quality goes down
so i been adding the xtra Octane Boost every other thank even tho i run 93 since November of last year , but i seem to be stuck at that
MPG, i have an HUD to monitor everything and no DTC present other than the usual Small emission leak that pops at random and when so
clean the filler neck mouth and will go away for months at time .One customer of mine suggested to change them regardless being year old
simply because low quality gas will hurt the performance while not bad enough to cause a miss but clearly enough to suffer fuel economy.

Wondering if i should just stick with OEMS or maybe venture a different brand
Been Thinking Denso TTs , NGK Yitrium or Iridium
I have always been a big believer that unless your are making 80hp over stock ,stick to OEM everything including manufacture heat range
just figured id take some suggestions/advice first and see what yall thoughts on the subject may be .

Thanks in Advance

 

[LionsTooth]

I agree...unless you are tracking the car, stick with OEM.

 

[scotman]

The Fiesta uses a double Platinum type of spark plug. The platinum material is super long lived. I pulled out the plugs on my 2011 at 60k and just re-gapped them and replaced the wire set.
At 100,000 I will install a new set of spark plugs, remove and clean the throttle body and replace the oxygen sensors.
I can’t remember what the odometer mileage is on your car . But, if you are running 93 octane fuel, you should be getting a bit better fuel economy than on 87!
I would suspect that the oxygen sensors, especially the upstream one, are getting tired or have been skunked somehow.

 

[Handy Andy]

There are several new "alloy-types" with Iridium being the hardest alloy most commonly available.

Several Ford engines need to utilize the Iridium as the "only" plug they use and pass emission and give the best performance with. That's something most Auto Stores can help you find - if you want to try them - just remember this becomes an expensive hobby if you go down that rabbit hole.

Well, that's all well and great, except for the fact that the side electrode, the grounding electrode side, might not be plated with the same material nor even have the wear resistance the center electrode has.

The issue of the Center electrode is normally what the make states on the package, does not always equate to the same material used for the side or ground electrode - which are more of a nickel-steel plating alloy - while platinum can oftentimes be plated on both electrodes, but that too, introduces wear and pitting conditions you have to figure on dealing with on a more regular basis.

Some plugs claim to offer less firing voltage requirement - which I find quite a confusing effort to sell a plug on the basis that the arc itself needs to ignite the fuel air charge, so to say "less voltage" might be a misnomer, for it may be "less current" that is needed to pass thru in the arc due to the construction of the plug and Iridium's inherited intrinsic traits of conductivity and hardness - which will make for a heat transfer condition that makes the electrode hotter, changing the way the arc can form and jump the gap to fire the charge.

In this example, the ARC forms where the closest point
between the two electrodes exists.
See how far the outer arm of the ground electrode sticks out,
yet it is not used for the jump or occurring close to where the charge resides
- so much of the electrode surface that can be used for the arc
- just sits there gathering carbon soot from the ignition and burn.​

• Perhaps it can be better explained in making the electrode design different - by making the electrode more of a pinpoint firing location - being that the direction of arc and where the arc can reliably form from - the construction of the electrodes and their design make more of a difference in ignition and how the heat formed during that arc discharge can be kept for the next firing sequence.
• There used to be an older ignition system that used a rotor cam off the distributor to operate Points and Condensor unit using a set of contacts that to reduce pitting and improve their life, they used a Ballast Resistor designed to reduce the current that the contacts sent to the coil - when the engine was running.
  • When you started the engine, that resistor was bypassed by the Starter solenoid sending power from it's relay straight to the point and condensor - so the system saw full voltage and made the plug arc from the extra boost in current - even at a lower voltage.

​

Back to Iridium - high tensile (brittle) high meting point also has the best corrosion resistance to deposits as well as best material deformation characteristics - so since it has a very high melting point - it can stay hot and shrug off carbon deposits that other cooler plugs would foul and lose arc due to the carbon trail losses in the gap making conductive paths so the arc can't form - it's found a route around the gap to ground - thru the deposit is an easier path to follow.

You need a high voltage to for make the arc even occur (breakdown potential needed in the atmosphere and pressure in the cylinder during compression) once that is completed - the current - or amount of power passed in the arc jump - is limited by other factors - including the plugs own internal suppression resistor and the ignitions' pulse duration and field density of the coil and it's winds - used to generate the induction to make the arc spark.

I was always a big fan of copper-core because of their low-resistance conductivity and less hot-spotting - that coppers thermal profile has, to provide better heat conductivity than many other metals.

Problems with copper is; it's low melting point and ductility, causing sputtering so you can lose the electrode to wear just from the hot arc and so you'll need to maintain them and recheck gaps and replace as needed - checking them on a regular basis as a schedule is the best for such material.

So to me, being a fan of older more proven metals has my vote, but in todays typical environment for driving, you'll need to stick with the plugs and the gaps they use specifically for that engine - nothing else - else you risk more problems with the mixture, tune and performance the engine would otherwise have just sticking with OEM.

So to me, the field of "plugs to use" is wide open - so as the old saying goes...

"If you Build the Engine - the Plugs will come" - now I don't know if Ethanol from Corn is responsible for that ethic, but use what works for you is the best advice we can give you.

Just dimension it and use the right heat range - you'll have just your senses to figure out what your engine needs.

 

[Mercurios2011]

I run motorcraft Sp525x which is OEM according to my Catalog at work , as far as the O2 sensors I replaced those when the header was installed roughly year and half ago
The only 2 other comparable options are NGK (ruthenium) or Denso TTs (Irudium) It doesn't list Double Platinum other than Autolite APP5363
However the owners manual does not list a specific part number , The car has 176,797 miles , service maintenance always been done thru Ford and or rarely myself
Other than the water pump timing belt job that car has never had any major repairs other than when the ac went out while under warranty.
I don't abuse the car by no means ,I drive it hard here and there but majority of the time I use the cruise control unless I'm going thru town which takes no longer than 10/15 min after that is pretty much straight shot home .
Thanks again yall !

 

[Handy Andy]

The only 2 other comparable options are NGK (ruthenium) or Denso TTs (Irudium)

Iridium (NGK)

Ruthenium (NGK)​

Ah, more Elements to add to this rather interesting list, not sure if it's a Geology, Engineering or Chemistry degree you'll need to further this endeavor, but let us know how this turns out!

But wanted to post the Construction of the Electrode in the plugs you mentioned - plays an important role in where as well as how that ARC will form.

So "conventional" plugs using standard electrode design that been around since - er, Momma was a twinkle in Grammas' eyes.- although still in use, good to see someone got creative with crayons on the Paper Placement at a local restaurant.


Enjoy - keep us posted on this.

 

[Mercurios2011]

So it appears that my problem lies else ware , or one of em , I went ahead and replaced plugs with Fords Motorcrafts even though there was actually nothing wrong with them , while I did found out was my serpentine had a nicked on the side and it was starting to rip, so replaced that as well , had noticed small voltage drops and temps going slightly higher than usual (220F) once or twice so that belt was definitely a factor . I cleaned the air filter , check for exhaust leaks (yet to check the header) and made sure tire pressure was correct .
usually takes about 2 weeks to get the best overall MPG results, hopefully that will be the end of that , I will open a thread later on with a video on a very small noise I hear @ low rpms less (than 2k)

 

[Mercurios2011]

...and just like that I'm back to 40.1 MPG, my dumbass forgot to reset it the AVG , now when I got On it went to 38.2MPG in matter of seconds and dropping

 

[Handy Andy]

Thanks for sticking with OEM - rules out other problems that can set a MIL light and the engine can suffer from it.

The reason for a lengthy post earlier was due to another issue of changing plugs to a different type - the fitment becomes more paramount in trying to repair or replace plugs later.

This thread might help shed light on why many stick with OEM to avoid hassles of having to find a different plug - then when you find it - the next guy has to figure out how to take it out to replace them back with OEM ones.

https://www.fordfiesta.org/threads/spark-plugs.8693/post-23009