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Hey everyone,

So a bit of background - Just had the engine rebuilt. While the engine was out the engine builder found that there was actually quite a large crack in the coil pack and everything was kinda corroded so it was all replaced (leads and coil pack). NOW - Here is the problem. I noticed the car was driving terribly and idling like crap so I had a look. Turns out one of the leads had popped off the coil pack (it was still in place, it just wasn't attaching to anything). Anyway, I played with the connection on the lead and managed to get it to clip into place. The car continued to intermittently drive like crap and I found that the same thing kept happening (with a different lead this time). So I fixed it and all was well again.

This is the part that really concerned me. Went for a drive this afternoon and then all of the sudden the car started idling like a rotary. I instantly pulled over and found one of the leads had popped off the coil pack completely and was just sitting out in the open with an open electric arc between the coil back and the base of the lead! Obviously this was kinda crappy as it seems like a great way to start a fire.

Anyone had any similar problems? Does it sound like faulty leads (they are OEM mazda ones) or is there something far more interesting going on?

Any help would be greatly appreciated - Thanks!

7Hazi wrote:Does it sound like faulty leads (they are OEM mazda ones) or is there something far more interesting going on?

Mazda MX5 OEM leads can have a fairly short life - sometimes they'll only last 20k kms - reckon it's the leads.

They were replaced along with the coil pack though. They have only done about 300km

93_Clubman wrote:

7Hazi wrote:Does it sound like faulty leads (they are OEM mazda ones) or is there something far more interesting going on?

Mazda MX5 OEM leads can have a fairly short life - sometimes they'll only last 20k kms - reckon it's the leads.

Sorry to disagree, but even very crappy no-name leads should last more than 20k, and even IF it wears, it will be the insulation around the length of the leads, and not the boot where it connects to the coil pack.
The most common failure with cheap-ass leads is melting, disintegrating, and bonding of the spark plug boots onto the the cam cover and/or spark plugs. The leads will still work ok, but as soon as you try to remove them, that's where the trouble starts.

Post up a photo of the inside of the errant boot that connects to the coil pack.

You live Northside don't you?

Andrew, the Mazda OEM ones are even crappier than the crappy leads! It's common for the OEMs to fail relatively quickly. However, agree you should get more than 300 kms out of them unless they were faulty to begin with!

just for reference my OEM leads lasted 110,000km before they died.

Perhaps their quality has improved (there was certainly room for improvement), as from 1990-2000 my NA6 was going through a set of OEM leads every two years. Changed to good non-OEM leads in 2000, & still running them.

mate
take the leads off [ one at a time if need be ] and clean the inside of the boot at the coil end with a litte carbo clean or mild solvent not to much though [ even run a bit of not to course sand paper around the inside of the boot]. A lot of the after market leads have a slippery film [ must be a protectant ] and when they get hot and a little engine vibration they slip out of the coil tower. Once cleaned your issue should stop happening [ I get a lot of cars with this issue in my workshop]
agent orange

1red5 wrote:

93_Clubman wrote:

7Hazi wrote:Post up a photo of the inside of the errant boot that connects to the coil pack.

You live Northside don't you?

Yeah, I am on the northside. Your photo request prompted me to take a closer look at the connection between the coil pack and the lead. Turns out that the little clip (or whatever) inside the connection on the lead was bent out of shape (when compared to other ones). I got the pliers out and bent it to look like the others. Car ran well for a bit and then it popped off again lol .

Agent Orange - Thanks for the suggestion. I did notice a lot of residue on the coil pack this afternoon and wiped it all down. I'll try cleaning out the leads though.

Worse comes to worse I'll probably just buy some new leads - I'd rather spend $100 and have the car running properly!