Chronic ignition coil problems

Can a problem elsewhere in the system cause ignition coils to go bad? I have an '03 Mazda 6s, 147k miles, owned it since new (Dec '02). 3 1/2 ~ 4 years ago, over a period of 6 months I had to replace 4 of the 6 coils. A month ago, one of the replaced coils went bad so I had all three rear bank coils replaced (cheaper to do all three at once rather than one at at a time since half the engine needs to be disassembled to get at them). This week, I started to get the initial symptom of a coil going bad on me: Occasional stuttering in the engine.

This issue always starts when it’s wet outside. The first few times it started when going through a car wash, this last time was right after Super Storm Sandy dumped a lot of rain (I am not in one of the flooded areas, NH just got a lot of rain).

Who Is Diagnosing These Coils As Being Bad ? Is It A Mazda Dealer ?
How Are They Concluding This ? Trial And Error ?

Besides, " Occasional stuttering in the engine, " Are There Any Other Symptoms, A “Check Engine” Light, DTC P0300, Etcetera ?

I think it’s really unusual to have all these coils go bad. I’m wondering about a faulty sensor, (camshaft, crankshaft), connector, etcetera.


Actually, you should have replaced all six coils back in '02. To the credit of the coil manufacturers, they have pretty consistant operating lives, and generally if the original set starts going bad it’s prudent to change all at once.

While stuttering IS a symmptom of a “missing” coil, it’s also a symptom of many other malfunctions. Stop by the local parts store and have them down;load the codes (most will do it for free). Post theme here and we’ll help from there.

Spark plugs. If a plug fails to fire, then the inductive kick builds up so high it will cause an internal arc inside the coil. Coils can withstand some misfires, but the internal arcing causes heat to build up, so if there is too much internal arcing, the coil will be damaged.

This is a classic symptom of bad plug wires. Moisture in the air allows the spark to jump through the bad wire to the block. This will toast the coil.

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Coil on plug, no spark plug wires.

I have a 2004, same problem. The Mazda V6 engine is a Ford Duratech. From what I have been told coil failure is very common with this engine. My mechanic actually keeps these in stock–only ones he stocks. I haven’t had to replace one in the last year or so.

A grounding problem can also lead to early coil failure. The COP design has the coil grounded to the engine block at the mounting screws typically. I got in the habit years ago to polish off the mounting points on the engine and coil and using some dielectric grease to prevent grounding issues at the coil.

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Sorry for the very long delay, the site never notified me of any responses.

To sum up answers to all:

The first time, a few years ago, the coils were diagnosed initially by the dealer, this time around I had the code read at a parts store and it came back “ignition system” on one of the rear bank cylinders. I then brought it to a reputable local shop (found here in the Mechanics Files) who diagnosed it as an ignition coil. Based on my first experience, I had them replace all three rear coils proactively, and I kept the two non-faulty ones as spares for when a front one goes bad. I believe, but I don’t remember exactly, that the effected plugs were also replaced at the same time. It’s a coil-on-plug engine. With the coil(s) replaced, the problem went away.

Other symptoms did include the Check Engine light.

I’m glad I kept the two “spare” coils because sure enough, a few weeks later I got the same symptoms and this time it was one of the front bank cylinders, which I could do myself so I did. And replacing just the coil the problem went away and has stayed away for over 3k miles (the car now has 151k miles). I wire-brush cleaned, but didn’t grease, the mounting surfaces.


congratulations are in order!

Hi! I know my post is kinda super late…i own a '03 Mazda Tribute (used) so its racked up almost 147k miles as well. My older brother and I just changed its ignition coil and ALL 4 spark plugs last year around July. N now, just yesterday it started sputtering and can’t make it up an itty bitty hill. Brought it to the shop and the mechanic was sure 2 of the 4 coils have gone bad. Spark plugs still good so i bought another ignition coil for an arm and a leg ($165!!!) and had the boyfriend change it. Could there be another cause of this thats making the ignition coil go bad that fast?

i think i will try this! THANKS!