yodano

I have replaced the coil pack in my daughters 05 4.0 mustang 3 times in one year and the last one only lasted for 3 weeks and it too is showing random misfires on 1-4-6 and the previous packs were all different misfire patterns. The last two coil packs came from auto zone. Auto Zone said that it must be something else causing the coil packs to go bad. I have had issues with bad electronics from auto zone in the past. My question is; Is there anything that could cause the coil pack to go bad? eeg issue, module issue, ect.
Plugs and wires are only 6-8 months old.
THANKS! Daniel

99GTvert

Do you have any coolant leaking out that could find its way into the plug holes? What brand are the coil packs?

Mine went bad on my car (though not a 05 v6) because I had a coolant leak which leaked into the plug wells/holes where the COP boot covers the spark plug. When I was considering which replacements, it seemed like OEM was the best way to go as some other random brands had bad reviews.

GrayPony

Have you checked the smart junction box for water damage/corrosion? 05 and 06 had a problem with water leaks.

wayne613

Using anything other than OEM replacement COPs is asking for trouble for our cars, for any model. Do a short forum search for accel cops, and you'll see what I mean.. Sometimes they'll be fine for a few months to a year, then crap out, others, you don't get so lucky.

Should you want further information (the thread is for the new edges, but is still completely relevant to our S197s, and the codes apply):
https://mustangforums.com/forum/4-6l...formation.html

yodano

What is the "smart box"? I do have some sort of leakage. Once or twice a month I do have to add coolant to the radiator, but I've never been able to find a leak. Nothing on the ground, nothing wet inside engine compartment. Thought it might be the 16lb pressure cap so I replaced it a year ago. It still leaks.

yodano

Thanks for the reply 99. How do I check for the leak? Thanks!

GrayPony

The smart junction box is in the passenger kick panel. 05 and 06 had problems with cowl water leaks hitting and corroding the box. Has the passenger side carpet ever been wet? (under the mat)

BTR-75

An even more basic question, does she attempt to clean the engine with water? Stranger things have been done, I was told by a friend who worked as a mechanic at a dealer of repeated problems they'd have after detailers cleaned engine bays with power washers which in turn caused the coil packs to be very angry.

JimC

I'd be surprised if washing the engine would cause a problem.

One the owners manual tells you how to do it (cover the intake, fuse box, and battery first).

Two, I used to do it all the time to my car. At least once a month I'd wash down the engine bay and spray it with the wand even at the "quarter" car wash. I put 200,000 miles plus on the car. I only replaced the coil at 150,000 + miles because I had one in the garage from another car, and thought I felt a miss on the highway.

yodano

Yes, my daughter says it leaks onto the passenger side carpet when it rains and it smells terrible. So its really looking like a "Smart Junction Box" issue. Ford didn't put it in a smart place huh! Can the Smart box be repaired, or replaced only?
I really appreciate your help; Thanks!