Spark plug Q's and gap info - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

88000&counting · 03-09-2008, 16:24

I have a bunch of spark plug questions and have searched all over but haven't been able to find the answer(s).
First, How often should one replace the spark plugs. I have a 98 and a 05 Taurus. The 98 has 88000 miles and I replace them about every 40k miles. The 05 goes about every 50k miles (I am not as attached to the 05 as I am with the 98) Does this sound ok?
Second why are the orig plugs that came with the vehicles different? The 05 taurus came with (3) AGSF22PM and (3) AGSF22PGM. The PGM's were hardly worn but the PM's needed replaced. Why? (non even wear)
Finally, I trusted the Napa store who sold me Autolite AP764's saying they were just fine for the 98 and put them in. Does anyone not like Autolites enough that makes me want to pay the high price Ford wants for Motorcrafts?
Thanks in advance all!!!
p.s. I found the gap info I needed finally (It was .042-.046)

btexpress · 03-09-2008, 20:54

Not sure why the factory plugs are different on some engines, bank to bank, but when replacing them use all the same number, no problem. Hopefully AP764 is the right Autolite. NAPA telling you they SHOULD be ok is like saying it's ok to spray aerosol in your eyes. Why can't they tell you these ARE the right plugs?

My shop uses Autolites in just about everything. Best to stay away from Bosch and Champion. You can go 100K miles on plugs if you care to, won't hurt the engine or cause problems. And gap can go as high as .060", you might see better performance with a bit wider gap. These systems produce plenty of power to fire a wide gap.

**tbird100636** · 03-10-2008, 05:12

Plugs shouldn't differ between banks. Should have bought one set of one # or the other. I always go with what the car came with. You can get Motorcraft plugs at AutoZone for relatively cheap.

**360ci** · 03-23-2008, 06:37

Quote:

Originally Posted by btexpress

Best to stay away from Bosch and Champion.

Not true. Champion and NGK produce the best copper plugs on the market. Besides, Champion is the only one to produce an F1 plug (three times smaller than reg spark plug) for high rpm racing applications. I run copper plugs in almost everything I won except my newer G6 which has platinum or iridium plugs (I forget which it has now). I change out copper plugs every 20-25 000miles for best performance. I'm the type of person who is a bit leery leaving spark plugs in for 60-100,000miles. After I had a platinum plug seize in one of my older car engines and had to drill it out, I went back to copper. If I wanted to run a cooler heat-range plug, Autolite would be the one I'd go with. Cheers.

SHOZ123 · 03-23-2008, 22:12

OEM Ford plugs on cars with the DIS ignition use single plats on one bank and double plats on the other.

Both have been replaced by the Motorcraft Fine Wire plugs. I like the Autolite XP iridium plugs myself.

RickMN · 03-23-2008, 22:43

360ci is kinda right about copper plugs--they really do give the best fire. But, as he said, they don't last nearly as long as plats or Iridium. My best advice is to NEVER keep a plug in for the whole 100K, even if the mfg says it's ok. First off, a 100K plug with 80K on it is already 80% worn. Second, and more important, they are a bearcat to get out at 100K, almost welded to the head.

Autolite is a good brand. I personally do not like Bosch--had too many problems with them.

Always use anti-seize and these days, always use a torque wrench. Deduct 10% of specified torque due to the anti-seize. Too little torque and they can leak. Too much torque and you can distort the plug body or damage the threads in the head.