robs87fox

Do any of you fox guys know maybe whats going on?

My car has been pissing me off. Its missing at high rpm's(WOT) and I've been trying everything.

All ignition is new and looks good

I changed the fuel filter, TPS(new& set at .98),new IAC, new coolant temp sensor,cleaned tb,and egr.

Buddy even scanned my computer and only thing was low tps voltage(which we reset)

The next thing i'm going to do is pull each plug out and check them-even though there only 1 year old.

do you guys think it could be a fuel pump or regulator?

rob

mstngsule68

get a fuel press. gauge and watch it.

robs87fox

i put new plugs in and it solved the miss. I just didn't think plugs with 12k on them would of been bad. But I guess running timing advanced with 91 oct. did there damage. Has anyone else had this happen when they advance there timing, is it normal for the plugs to wear this fast. I had ngk plat. in there.

rob

mstngsule68

im not a big fan for ngk, i havent heard good stuff personally...

U S Marine

I would still check the fuel pressure. Lean condition will burn plugs. How old are your O2 sensors? I've run NGK in the past with good success. I've had them installed in a 10.75:1 comp engine for 45K miles. How did the plugs look? Clean? Grey? Black? Red? White? Green(ish)? I will tell you this; I generally stick with Motorcraft or Autolite in Ford engines. The ignition systems tend to run hotter than GM.

robs87fox

the plugs looked greyish white.

???on the 02 sensors, i've only had the car for 15 months. They maybe original

I used autolites this time

67mustang302

They could have just worn enough of a gap that they were misfiring. Post pics of the plugs.

robs87fox

I inspected plugs closer and discovered one plug had 2 cracks on it...

do plugs just crack like that...or perhaps I did it when installing headers, i might have bumped it???

rob

U S Marine

Greyish white is fine. You could pull codes to see if the O2's set a code. It's a good idea to change them if they are over 60K-80K miles. A craked plug will definitely cause a problem.

67mustang302

Cracked plugs will short through the crack to ground since it's usually a lot less resistance than trying to jump the gap of a plug in the high pressure, fuel saturated, high heat environment of the chamber. Some plugs just suck and are fragile. I don't like Bosch for that reason, they crack the insulators just way too easily imo. But over torquing them can crack them, as well as hitting or flexing them.