FlamingoGT

It is past time for a tune up and I was hoping for some help in finding the better spark plugs to use. The only really helpful post I found was in the Tech articles, but that was from 06, and there has been some improvements in the technology since then.
The car is a DD 04 GT vert with no real mods to affect this choice. I want to keep the per plug price reasonable related to its expected life and performance. Any true help is greatly appreciated.

speedkills

I just changed mine using oem motorcraft spark plugs.

These: http://www.americanmuscle.com/ford-s...gs-9904gt.html

cliffyk

AFAIK there has been no major advance in spark plug technology for the last 30+ years--though there are a lot of snake-oil salesmen claiming there have been. Run any single platinum plug you like and you'll be good for another 80k miles.

I run Champion stk # 3401 platinums, they got me to 262/305 with basic bolt-ons and an optimised tune...

FlamingoGT

On NAPA's website for the Champions, they recommend replacing the coil boots... any thoughts on that? And is that easily done with the stock COPs?

cliffyk

If you have over 75k to 80k miles I would recommend replacing the boots. It is failure of the boots and/or plug wear causing excessive gap that weakens and breaks COPs. In normal use a COP never dumps it's full charge, however when the boot fail to insulate properly more and more of the COPs charge will be dissipated through the boot and into the head. Using my COP Tester/Destroyer I can kill a COP in 15-20 rapid succession full charge dumps:



Here's a video of a stock COP firing across a 16 mm gap.

This causes the COP to overheat and burn-out (the insulation of the coils breaks down). You can get new boots and springs here for $3 each.

I replaced mine at 85k or so and am now pushing 115k with the original COPs...

Justin00GT

While we're on coil boot.

So cliff, I replaced that cylinder 4 coil (with the ebay one) and the car runs perfect. So far.

My question is does water ever get back in that bank that you've seen? My COP had some wetness I first thought was oil, but upon further inspection it was dirty water. The bottom of the coil boot was enlarged a bit, I'm guessing from absorbing the water. No cracks other than a super tiny one running lengthwise at the very bottom. Maybe 1/4" long.

cliffyk

I have never known any water to get in there, other than from someone washing the engine and not being cautious...

Justin00GT

Hmm maybe it was coolant that got dirty as the coil boot had some gunk on it. I still don't understand where the coolant comes from and how it gets in the wells. From my BMW days, it was only oil.

cliffyk

Coolant runs through the crossover pipe at the front of the intake manifold, and up through the manifold to the heater core back near the #4 plug--it is fairly common on the older cars for that rear nipple to crack and leak coolant out across the head and possibly into the plug well.

Coolant in the plug well provides a path for the COP to dump its full charge at each firing, burning out the COP in fairly short order.

Justin00GT

Do you have a photo of what this cracked area looks like? I just checked with a flashlight and can't see much with the mess of hoses and stuff back there.

I smelled the dead COP and it definitely smells of coolant. I thought Ford replaced the faulty intake manis under a recall? The P.O. did mention something about it being replaced.

EDIT: I just did some research and my car did in fact have the original plastic coolant piped intake manifold replaced with the updated one (aluminum front coolant pipe). I just went out in pitch black with a bright flashlight and saw not a single wet area (checked by COPs, injectors, under manifold, etc). Even tried smelling for coolant and nothing. P.O. said the manifold was replaced like 5 years ago (during that recall). I don't know what to think of cylinder 4 being wet. It was too far back to look into the plug well, so I just am going by the coil boot having wetness on it. I am waiting for the plugs to come in before I tackle them and the other coils. I just don't want to kill a new coil because there is a coolant issue in that cylinder. :/