Spark Plug designation?
Thread Starter
|
New User
Joined: Jan 2006
Posts: 3
Likes: 0
Spark Plug designation?
Hello, new here and asking obo my daughter who has an 03 F150 Sport with the 4.2L V6. She had always complained about poor mileage despite having overdrive and when I pulled the plugs at 46,000 miles the gap was around .060 and they were Motorcraft OE? Platinums but this is the mystery. On the left bank the plugs were AGSF 34EM and the other bank has AGSF 34EGM. Motorcraft's website doesn't list either part number but does list AGSF34FMF6 or 34C as the correct plug.
First Q is this, is there a heat range difference in these plugs? What (is) the difference? I'm assuming they are the factory plugs.
In any event, why the poor mileage? Hopefully the new plugs, Autolite 5144s will make a difference gapped at .044 but I'd still like to know why her motor had two different plugs in it?
Motorcraft's website and info number couldn't help and referred me to my nearest Ford Truck dealer and their service and parts mgr couldn't help me either.
Thanks for any information you can provide.
First Q is this, is there a heat range difference in these plugs? What (is) the difference? I'm assuming they are the factory plugs.
In any event, why the poor mileage? Hopefully the new plugs, Autolite 5144s will make a difference gapped at .044 but I'd still like to know why her motor had two different plugs in it?
Motorcraft's website and info number couldn't help and referred me to my nearest Ford Truck dealer and their service and parts mgr couldn't help me either.
Thanks for any information you can provide.
Post Fiend
Joined: Mar 2003
Posts: 14,413
Likes: 3
From: Sarnia, Ontario, CANADA!
Hi and welcome to FTE! Be sure to read this to help you around this site: https://www.ford-trucks.com/forums/s...88#post3272088 There are also State, Provincial and International Chapters located near the bottom of the main forum page.
We are glad to have you. Hope you enjoy the site. Check out the various forums. Lots of great info for you.
Thread moved to 4.2L V6 engine forum.
See ya on the boards!
-Matt
We are glad to have you. Hope you enjoy the site. Check out the various forums. Lots of great info for you.
Thread moved to 4.2L V6 engine forum.
See ya on the boards!
-Matt
Senior User
Joined: May 2004
Posts: 282
Likes: 0
From: B'ville, WV
If I remember correctly, one side is single platinum and the other is double platinum when you pull the stock plugs. Mine was the same way on my 2000. The Ford parts guy I talked to didn't know what I was talking about either when I asked why he gave me 6 of the same plugs.
I do remember this being addressed in an old thread. You might find it doing a search in this forum.
Isn't .044 a little close? I thought the rec. gap was .052-.056? Just curious?
Rich
2000 XL 4.2 5spd 127,XXX miles
Not running as of this this evenings commute home
SES on for the first time, so I can't complain too much...yet
I do remember this being addressed in an old thread. You might find it doing a search in this forum.
Isn't .044 a little close? I thought the rec. gap was .052-.056? Just curious?
Rich
2000 XL 4.2 5spd 127,XXX miles
Not running as of this this evenings commute home
SES on for the first time, so I can't complain too much...yet
Postmaster
Joined: Aug 2001
Posts: 4,532
Likes: 5
From: Trussville, Alabama
jakerin,
Welcome to FTE and the 4.2 forum. Glad you found us and hope you visit often!
What you found with the two different plugs is normal. (for the OEM factory plugs)
One side is a single platinum and the other side is double platinum.
If I remember correctly, this is due to the polarity of the voltage sent to the 2 different banks (+/- vs -/+). I know the answer is somewhere at FTE, but it's been so long I can;t remember excatly where I found it.
Anyways......
If you had gone with platinum plugs for replacements they would have been double platinum. But, it looks like you went with what I did in my previous (2000) 4.2:
https://www.ford-trucks.com/forums/s...ht=spark+plugs
The Autolite copper plugs worked fine and were way cheaper than platinum plugs.
Don't neglect the wires, but 46,000 might be a bit early to need replacement.
What is her MPG? City and hiway?
There tends to be a fairly wide variation when it comes to MPG. I tend to think the single biggest factor is how hard the truck is driven. I can easily vary my mpg by 2-3 mpg depending on how I drive it.
You can use the "search" feature to search this forum for more info on both spark plugs and MPG.
There are plenty of old threads here with all sorts of info.
Again, glad to have you here.
edit: I do seem to remember gap being around .050. I think the sticker on the fan shroud indicates the proper spark plug gap.
Welcome to FTE and the 4.2 forum. Glad you found us and hope you visit often!
What you found with the two different plugs is normal. (for the OEM factory plugs)
One side is a single platinum and the other side is double platinum.
If I remember correctly, this is due to the polarity of the voltage sent to the 2 different banks (+/- vs -/+). I know the answer is somewhere at FTE, but it's been so long I can;t remember excatly where I found it.
Anyways......
If you had gone with platinum plugs for replacements they would have been double platinum. But, it looks like you went with what I did in my previous (2000) 4.2:
https://www.ford-trucks.com/forums/s...ht=spark+plugs
The Autolite copper plugs worked fine and were way cheaper than platinum plugs.
Don't neglect the wires, but 46,000 might be a bit early to need replacement.
What is her MPG? City and hiway?
There tends to be a fairly wide variation when it comes to MPG. I tend to think the single biggest factor is how hard the truck is driven. I can easily vary my mpg by 2-3 mpg depending on how I drive it.
You can use the "search" feature to search this forum for more info on both spark plugs and MPG.
There are plenty of old threads here with all sorts of info.
Again, glad to have you here.
edit: I do seem to remember gap being around .050. I think the sticker on the fan shroud indicates the proper spark plug gap.
Thread Starter
|
New User
Joined: Jan 2006
Posts: 3
Likes: 0
Thanks guys. I'll be checking her mileage as time goes by. I still don't understand why double platinums are installed on one cylinder bank and not the other??? And, why replacing them shows no indication of this 'factory' preference. Its running fine so we'll see how and if the mileage improves.
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Originally Posted by jakerin
Thanks guys. I'll be checking her mileage as time goes by. I still don't understand why double platinums are installed on one cylinder bank and not the other??? And, why replacing them shows no indication of this 'factory' preference. Its running fine so we'll see how and if the mileage improves.
Replacements are done with either double plats or finewires, eliminating the need to stock and to install two different plugs when changing them. At the retail level, the cost per job is not significant.
Fine-wires, while a single plat design, eliminate the need for a double plat and replace both the singla and double plat conventional design.
Steve
Last edited by projectSHO89; Jan 19, 2006 at 09:20 AM.
Thread Starter
|
New User
Joined: Jan 2006
Posts: 3
Likes: 0
"Replacements are done with either double plats or finewires,"
So, is there anything wrong with replacing them with Autolite 5144s? They aren't platinums much less double plats.
So, is there anything wrong with replacing them with Autolite 5144s? They aren't platinums much less double plats.
Trending Topics
Postmaster
Joined: Aug 2001
Posts: 4,532
Likes: 5
From: Trussville, Alabama
The Autolite copper plugs will work fine. I used them, as have quite a few others.
I understand the reason for platinum is to provide longer replacement intervals.
The coppoer plugs will not last as long but are easliy replaced and cheap.
I'd figure 20-25,000 miles or so for the copper plugs.
I understand the reason for platinum is to provide longer replacement intervals.
The coppoer plugs will not last as long but are easliy replaced and cheap.
I'd figure 20-25,000 miles or so for the copper plugs.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Thread
Thread Starter
Forum
Replies
Last Post
