2 types of stock spark plugs?

[Tim Mason]

Well, after 99,000 miles I decided to change the spark plugs in my '02 4wd. I realize now that if I ever do this again I'll have to warm up by:



1) Sitting on a chair in front of the grill for 20 minutes and screaming at the Ford emblem, might as well get it out of my system early.

2) Practice crawling under my truck to the exact dimensional center to retrieve sockets, extensions, and swivels.

3) Heading down to the hospital and donating a pint of blood and skin samples ahead of time.



Anyway, when it was all said and done I found that the driver's side plugs were different than the passenger's. The driver's side had Motocraft AGRF-22P's and the passenger's side had Motocraft AGRF-22PG's. There is a slight visual difference in the electrodes. Both sides looked normal as far as wear & tear. The new ones are AGSF-22FM's. Is there a significant difference or reason why Ford would use 2 different types??

 

[Rodger Tellefson]

:rofl:



That's a very good question as to why Ford would use 2 different types, but I would go with what the dealer shows for the latest part no. all around.

 

[Jim parnell]

Are you the original owner? If not, maybe the original owner changed them and they were packaged wrong, or he got tired after the first 3 and quit. Ah, Quality is Job 1.

 

[EddieS'04]

Not odd at all. Some of the early tracs came that way oem. No one noes why. As long as you used motorcraft or autolite replacements, your ok.

 

[scott degroot]

I know why they use 2 different plugs......it's got to do with the way the coil fires. One side of the coil fires positive polarity adn the other side of the coil fires negative polarity. This firing difference causes the plugs to wear different so Ford uses 2 different plugs to even out the wear. The first time I saw this was on the 4 cylinder engines that they used to put in Rangers that used 8 spark plugs.

 

[EddieS'04]

1tech, Why dont the parts houses, sell two diferent replacements, when looking them up.

 

[Tim Mason]

To answer an earlier question, yes, I am the original owner and this is the first plug change it's had.



I have the week off so I not only did this but dropped the tranny pan, installed a drain, tightened the solenoid adjustment 1/4 turn, and put in 5 quarts of Royal Purple.

 

[scott degroot]

by EddieS'04,7/15/2010 17:56 MT



1tech, Why dont the parts houses, sell two diferent replacements, when looking them up.

I can't answer that...I just know how and why the systems work, I can't speak for the part suppliers.

 

[Richard McAlister]

I remember my '97 Lincoln 4.6L having a different plug for each bank. They were platinum plugs, one bank had the platinum on the center electrode, the other bank had the platinum on the side electrode. Technician at the dealership said it was to save money, the replacements had platinum on both electrodes.

:driving:

 

[Jim parnell]

well, job well done anyway.

 

[Johnny O]

I know why they use 2 different plugs......it's got to do with the way the coil fires. One side of the coil fires positive polarity adn the other side of the coil fires negative polarity. This firing difference causes the plugs to wear different so Ford uses 2 different plugs to even out the wear.

I remember my '97 Lincoln 4.6L having a different plug for each bank. They were platinum plugs, one bank had the platinum on the center electrode, the other bank had the platinum on the side electrode. Technician at the dealership said it was to save money, the replacements had platinum on both electrodes.

Both of the above are basically true. One plug has a platinum tip and one is a double platinum. The double platinum has a different part number and is the recommended replacement plug. The owners manual for the '99 Ranger I used to have described this.

 

[Tom Schindler]

One side of the coil fires positive polarity adn the other side of the coil fires negative polarity.

OK, never heard of that. Interesting.



One question, if the chassis is ground, how does a coil fire a negative charge to a plug that is grounded negative? If both the block is positive and negative charge, how does that work?



Just wondering. I have a little electrical background and I know what needs to be present to get electricity to flow. Negative to negative just doesn't happen.





Tom

 

[scott degroot]

I can't really explain the technicial side of it as electricity isn't my strong point when it comes to discussion...I can visualize it in my head but can't explain it. Google will bring up some references but nothing that really explains the technicial side of it

 

[Johnny O]

Also this is the reason why late-model Fords do not run well with Bosch or other multiple electrode spark plugs. The bank that fires from the electrode to the tip gets confused because there is more than one electrode and the plugs on that side foul pretty quickly.



Tom, just a guess since I'm not an electrical engineer and did not stay at a Holiday Inn Express last night, but possibly the polarity is also reversed on the coils on that side.

 

[scott degroot]

JohnnyO,7/18/2010 11:26 MT



Also this is the reason why late-model Fords do not run well with Bosch

Nothing runs well with Bosch plugs

 

[EddieS'04]

Nothing runs well with Bosch plugs

Amen...

 

[Johnny O]

Nothing runs well with Bosch plugs.

It doesn't keep Auto Zone from pimping them strong though. :haveabeer:

 

[Andy Cabrera]

Nothing runs well with Bosch plugs

I put Bosch Ir Platinum plugs in my track last year. Started out fantastic but has been losing MPGs lately. I will be replacing them with OEM soon.

Really looking forward to that!

 

[Tom Schindler]

Tom, just a guess since I'm not an electrical engineer and did not stay at a Holiday Inn Express last night, but possibly the polarity is also reversed on the coils on that side.

Spark Plugs have one electrical connection to it. That connection is the plug wire. It is one half of the circuit. The other half is the engine block, which is the ground.



What l1tech says makes perfect sense and sounds totally logical, but I just cant understand how electricity can flow negative to negative and creat a spark, UNLESS the potential is different or something, but then again I don't know electricity as well as an electrical

engineer should.



Some of our resident know-it-all's should be able to explain this. I pray one of them give us the answer.





Tom

 

[scott degroot]

Ok I think people are getting hung up thinking everything flows positive to negative and what we should be looking at is differential. Opposites, such as protons and electrons, attract. With the waste spark system, such as what is on the ST with one coil pack firing 2 cylinders, the system gets overcharged with with either protons or electrons and will cause the negative firing incident to occur. It is the proton/electron difference between the 2 poles that causes the firing event to occur....at least that is my feeble attempt to try and explain how the system works.