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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Tue, Dec-13-2016, 09:15:04 PM   #1
MyGuitar
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Default Ignition Coils, code P0306 remains, slight knocking

Hey M3 peeps,

Here's a bit of a weird scenario surrounding ignition coils. My search didn't find anything with the same symptoms so I hope this thread is informative as I post updates when these issues are cleared up.

I was driving to get coffee on Friday after Thanksgiving and the car just sank - roughness, misfire sound, and loss of power! SES light came on after a minute or so, but the car still ran so I slowly limped it back home since I wasn't far away. I couldn't get the code read right away - but I knew from the symptoms that it's likely the ignition coils. At 99,000 miles, I had actually been thinking about replacing them only weeks before this happened. I got online and ordered 6 new coils.

I tested and replaced the coils last Wednesday. The test revealed that it was only #6 that was bad. Due to snow and my car being on Pilots I didn't get a chance to test drive until Friday. I've been driving it daily since then and the SES light is still on, but it drives fine and I can feel a slight increase in power/response compared to the old, original Bremi coils that were in there before. I stopped at AutoZone to read the code and it returned P0306 - Misfire Cylinder 6. There are no other codes.

The odd thing is, the valvetrain is noticeably louder now than before the coil failure. It's an amplified ticking around 2500-3300 RPM. I don't know what to make of this since the car runs fine, but the SES code is still there so I am wondering if another issue might exist. Is the SES supposed to clear itself?

I didn't change the spark plugs because that was done last year during inspection 2, but could the bad coil somehow affected the the plug to where it's still causing a "small" misfire?
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Old Tue, Jan-03-2017, 03:03:18 AM   #2
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Default Re: Ignition Coils, code P0306 remains, slight knocking

I replaced the spark plugs, but the ticking noise at 2-3K RPM has not gone away, and neither did the SES light. The car runs excellent, but I'm still trying to figure out what else could cause the ticking before I take it to dealer for a diagnosis.

This noise started after a failed coil - what else can a coil possibly take out when it goes bad? Injector? Valve shims? Harness?
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Old Tue, Jan-03-2017, 04:33:21 AM   #3
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Default Re: Ignition Coils, code P0306 remains, slight knocking

You may want to park for a while until you can have someone take a look at the vanos.
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Old Tue, Jan-03-2017, 05:01:05 AM   #4
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Default Re: Ignition Coils, code P0306 remains, slight knocking

Could it be vanos tho? Can an ignition coil cause that damage? Vanos was replaced 4yrs/22k miles ago.

I am looking at plausibility of a loose tensioner, bad injector, or a vacuum issue.
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Old Tue, Jan-03-2017, 05:54:11 AM   #5
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Default Re: Ignition Coils, code P0306 remains, slight knocking

Do you think limping it back home on a bad coil could cause any damage?
I ask because the same thing happened to me a couple weeks ago
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Old Tue, Jan-03-2017, 06:14:54 AM   #6
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Default Re: Ignition Coils, code P0306 remains, slight knocking

I *thought* it wouldn't, it was about 3 miles of 35mph. It could be that something was already on the way out and this incident helped nudge it over the edge. In most cases I've read about, simply changing the coils and maybe the plugs fixes the issue.

I've dug through some other, more technical forums and found a video of another car with the same noise at 2-3k RPM, and that one turned out to have a bad timing chain tensioner. I will inspect that this week and have it replaced if needed.
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Old Thu, Jan-12-2017, 01:16:38 AM   #7
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Default Re: Ignition Coils, code P0306 remains, slight knocking

I have narrowed my rattle down to the upper timing chain guide, still not a 100% sure, but that's the area I suspect as the source of noise.

Before I do anything, I wanted to find out how to change it. I haven't seen a DIY anywhere other than the ones when it's done as part of a Vanos rebuild or update. Is it possible to change the guide without taking apart the entire front of the car?
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Old Thu, Jan-12-2017, 08:37:29 AM   #8
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Default Re: Ignition Coils, code P0306 remains, slight knocking

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Originally Posted by MyGuitar View Post
I have narrowed my rattle down to the upper timing chain guide, still not a 100% sure, but that's the area I suspect as the source of noise.

Before I do anything, I wanted to find out how to change it. I haven't seen a DIY anywhere other than the ones when it's done as part of a Vanos rebuild or update. Is it possible to change the guide without taking apart the entire front of the car?
You have to remove the vanos to access that guide, which is quite straight forward.
You won't need to retime your engine since you are not removing the hubs.
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Old Thu, Jan-12-2017, 04:59:05 PM   #9
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Default Re: Ignition Coils, code P0306 remains, slight knocking

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You have to remove the vanos to access that guide, which is quite straight forward.
You won't need to retime your engine since you are not removing the hubs.
Oh cool, I can then inspect the hubs while in there as well.

Thank you!
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Old Thu, Jan-12-2017, 09:45:32 PM   #10
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Default Re: Ignition Coils, code P0306 remains, slight knocking

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Oh cool, I can then inspect the hubs while in there as well.

Thank you!
You should be able to pop the valve-cover off and see the issue without doing anything past that. The hubs will be visible as soon as the cover is off

Sounds awfully similar to the HUB break that I just went through
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Discussing Ignition Coils, code P0306 remains, slight knocking in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)