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· Registered
'02 ETC 34,000 miles 2002 F55 STS 83,000 miles, 2016 Challenger SRT 392, 6 Sp.
267 Posts
Discussion Starter · #1 ·
So., about a month ago I'm driving to Denver. About half way (200 miles) I notice the engine missing as I try to accelerate up a hill at about 70 mph. Then it runs fine until I get to Denver. When I stop I notice it's missing pretty noticeably when idling in Drive, but not in Park.
The next day driving around it is missing pretty badly accelerating from a stop. SES light blinking intermittently.

I try to hammer it hard a few times to smooth it out. Seemed to go away as speed built up.
Then after driving another 30 miles or so on the highway, the symptoms just disappear. Ran fine on the trip home, running fine now. No sign of any misfire.

Didn't pull codes as I figured I'd just get P0300 in history.

What does this sound like? Clogged injector that managed to unclog itself? I have run Techron through it., but several tanks ago.

I have noticed a hairline crack in both my coil cassettes, I expect to have to replace them soon, but if this was causing the misfire would it likely be intermittent and then just disappear?
I know there are a whole slew of things that could cause a misfire, but how many would be intermittent and then just vanish?

TB is clean, FPR is nearly new. About 69,000 miles now.
May be time for new cassettes, plugs and boots.

· Administrator
2002 F55 STS, 2014 Explorer XLT, F-150
80,404 Posts
Cracks in coil (cassette), boot, or (not your case) plug wire insulation can harbor moisture - a perfect short to ground. Stuff heats up, moisture evaporates, and the cycle waits to start again after a humid evening cooldown.

Just one of a dozen possible scenarios ................. Time for a beer and thorough condition/cleanliness checkup.

· Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
22,636 Posts
Didn't pull codes as I figured I'd just get P0300 in history.
you should still check for codes -

if you do get the P0300 -
a good hand-held scanner WILL read the individual cylinder -
P0301 - P0302 - P0303 - etc -
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