PerryB

I put new Motocraft 515's in my 05/5.4 about 41,000 mi ago. Recently it began getting fussy to start when warm or hot. I suspected dripping injectors so I replaced them (it was on my to-do list anyway). No change in the problem, so I pulled a couple plugs and the electrodes are almost gone! The gaps have burned open to about .085-.090. New plugs are about .050. Another set of new plugs fixed the problem but I'm stumped. I'm running an Edge Evolution on level 2 (Tow/Performance) with a couple minor tweaks to shift and lockup points, along with tire and gearing corrections. I have timing set at minus 1 degree (or maybe its minus 1.25-have to go check) because I usually just run regular gas.
For now I'm going to put the Evo in Trans. Only mode to fix the tire/gearing issue but leave the engine parameters stock. I'm baffled and a bit bothered by this. FWIW, I changed the original plugs at 95,000 mi and they looked a lot better than these do with 41,000 on them. Looking for ideas, thanks.

Summers22

iTrader: (2)

Interesting as I have had my SP515's in now for about 40k and I have just recently noticed what I feel is like a small stumble/miss at highway cruising speeds. Maybe I need new plugs as well. I to run the Edge converted to a Gryphon on level 2 with timing ADVANCE of +1 degree for my 91 octane.

PerryB

I'm at a loss for a plausible explanation to this. I don't think the tuner employs a multiple spark strategy, and even if it did I don't know if that would cause such rapid wear. I've run MSD systems on a few different performance vehicles over the years and never detected any accelerated plug wear. I can't imagine any reasonable air/fuel mixture causing this either. My tailpipe runs a thin light gray, the same as it did pre-tuner. Prior to the new injectors I ran a couple stiff doses of Techron through it, but nothing crazy. Enough to do up to 40 gal. in 25 gallons of gas.
As mentioned earlier, I've un-tuned for the moment until I can come up with some better ideas. Summers, if you pull a couple plugs let me know what you find. Thanks.

Summers22

iTrader: (2)

I sure will. I do notice a light black smoke upon hard acceleration, which from my research is from my use of high octane gas coupled with timing advance.

PerryB

I would also guess that your more aggressive tune runs a fatter fuel trim at or near WOT to provide some extra protection against detonation and some additional cylinder/piston cooling.

Summers22

iTrader: (2)

I am sure it does

techrep

iTrader: (1)

Did you replace springs and boots with the plugs ?

PerryB

When I changed the plugs their first time, yes. That was 41K mi. ago. The boots looked great this time. Actually they looked good the first time too, but at 10 yrs old I changed them just because. The truck runs beautifully, with the new plugs and injectors its the smoothest idling 5.4 I've seen. When you stomp it, it takes off like a shot. No hesitation, surge, miss etc. I read an opinion on another forum yesterday stating that old/failing COPs can cuase short plug life. I can see misfiring and fouling as a result, but not prematurely burned off electrodes. Maybe I'm missing something here.
When I did the first set of plugs (chronologically about 1-1/2 yrs ago... I drive a lot) I was going to change the COPs. The counter man asked how the old ones looked. Any evidence of arcing, cracking, tracking etc.? I said no, and advised him the springs and boots were still surprisingly good as well. Also runs great at WOT. He advised to change out springs and boots but not spend money on coils it doesn't need. He and I both agreed that a bad coil(s) would be fairly obvious, and that if the plugs, boot & springs aren't allowed to get too bad - excessive resistance - the coils usually last forever. FWIW I've known this man for at least 15 yrs and he knows his stuff. He's not just a parts pusher, so I give his opinion some weight. Anyway, continuing thanks for any thoughts/ideas and still scratching my head.

techrep

iTrader: (1)

Agree with your buddy

DualXhst289

I know this is a old thread, but, did you ever figure out what was burning your plugs up? I'm having same issue. Except I've only got about 15k on the plugs that just went bad. Truck is super chipped on performance