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  • Has anybody bothered to replace the sparkplug wires?

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 #76578  by JohnCollins
I was on the NGK website looking up plugs for my M when I saw a blurb on the wires. Nobody here really talks about them, so I figure probably not an item worth replacing, but I thought I'd ask.


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 #76584  by vegas
There are no "spark plug wires" on the M, our ignitions are known as "coil over plug" or various other similar names, but what it comes down to is that there is no conventional high voltage spark plug wire, just two normal wires, I believe 16 gauge. One delivers ground to each of the six coil packs, and one 12volts, one of these beign switched by the pcm to control firing.

The coil which develops the high voltage required for a spark to travel from the electrode of the plug to ground mates directly to the spark plug, thereby eliminating the need of a special wire we call a "spark plug wire". This does a few good things for us like:
removing a costly part of routine maintenance in replacing wires
provides a more reliable means of getting our high voltage to the plug (no wires to fail or open)
MUCH LESS electromagnetic inductance induced into the vehicles electrical system and radiated in general under the hood. No matter how good plug wires are shielded for your typical car, they leak magnetic waves all over the place which are picked up by your radio and any other electronic devices.

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 #76602  by JohnCollins
Thanks, Vegas!

I'm getting an ejumication here. Obviously I don't know a lot about cars. I'm just picking up maintenance tips. I appreciate the lesson!


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 #76603  by vegas
no prob, when i first bought the car, I didnt notice the setup, and wanted to do a tuneup and was asking in advance auto what the wires cost, and nobody could find a part number, glad eventually I figured it out myself before someone could make me look like a dumbass in public! 8)

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 #81926  by JA Cumbo
Hey, i dont feel as bad now. :D When i first got the car, i kept trying to find the spark plugs and wires. I finally realized that the plugs are being hid by the coil packs and that everythign is pretty easy to get at. Planning on doing a lot to it when it hits 100K miles (timing belt, water pump. plugs, etc)

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 #146030  by Arved
I hate to resurrect an old thread, but the 2000 owners manual does list spark plug wire change at 100K miles (Federal Emission Control Vehicles) and 105K miles (California Emission Control Vehicles).

Yeah, yeah, I know the engine has coil over plug. There are no high tension wires. I figure the guy who wrote the owners manual knew it, too.

So what's up with the plug wire change? Is this listed in the service schedule for 2001+ LH models?

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 #146035  by mnitetrain
JFYI, I'm still running the original coil packs although I do carry a spare one I picked up at Advance Auto parts.

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 #146355  by Ledgic_13
this set up did not surprise me, before i owned a Chrysler i had a 1991 BMW e34 525i. which of course has the ignition coils. there was a set of performance coils i put on that car, i wonder if that would work on our m??