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Discussion Starter · #1 ·
Hi all,

Here's the story:

My Beetle is a 2003 with 160K miles, convertible, 2.0L gas (BDC) engine, 6-speed tiptronic transmission.

Last week out of the blue, she sputtered on start up and I got a blinking CEL light. Hubs ran the OBD II and it pulled P0302, or misfire in Cylinder 2. He changed the spark plugs and added some fuel injector cleaner and that seemed to solve the problem.

Until today. Same thing happened, same code pulled from OBD scan. We've had heavy rain for the past few days, so I thought it might be the ignition coil based on this thread: http://newbeetle.org/forums/2-0-liter-gas/26525-misfire-cel-light-blinking.html

My question is this: is there a good way to tell (without VAG-COM, which we can't get to work on my car) whether it is the ignition coil GermanAutoParts.com , ignition wires GermanAutoParts.com or both?

And if so, is there a good DIY with pictures? I looked for the one on the Vortex but it looks nothing like the inside of my car. Everyone says it's easy-peasy, but there are virtually no instructions. Just trying to determine if we can tackle this ourselves or have to go to the dealer.

Thanks much for any advice!
Kaela
 

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Discussion Starter · #3 ·
We have not changed the wires, either the spark plug or the ignition coil wires. I think my order of 'diagnostic' replacement would be: SP wires, ignition coil wires, then ignition coil itself.

Thanks for the tip on the water: I actually just found that same tip on YouTube a few minutes ago! Much easier than messing about with voltmeters and such.

I just wonder why, if it were the ignition coil, the error code would be consistently in cylinder 2. It makes me suspect that the problem is specific to that cylinder, rather than the whole ignition coil.

And I've seen air intake, cracked distributor cap, MAF...seems like a difficult code to diagnose properly. :(
 

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Jitterbug
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The 2.o coil pack is two coils, each of which fires a pair of cylinders, 2 & 3 are fired by one coil, 1 & 4 by the other.

Consequently a single cylinder misfire is usually (in descending order of likelyhood and increasing cost):

Plug
Wire
Coilpack
Injector
Mechanical (eg valve or piston problem)
 

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The 2.o coil pack is two coils, each of which fires a pair of cylinders, 2 & 3 are fired by one coil, 1 & 4 by the other.
No!No!No! It is engine dependent! I have AZG and sparks are not wasted! I had this misconecption before I realized that fact!
If your coil pack looks like the following, then sparks are not wasted:
 

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Discussion Starter · #7 ·
Yep, that looks like my coil pack. So I guess my sparks are not wasted, but I'm not sure what that means to my diagnosis. Is it not just as likely that an issue with the ignition coil itself would impact more than one cylinder?
 

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Jitterbug
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Whether sparks are wasted depends on the ECU, not the coil pack. Yours has 4 coils vs 2 on the AEG/AQY however my understanding is that the ECU still triggers them in pairs.

However it does mean that a single cylinder could be the coil pack however due to cost and simplicity I would still go with my sequence above of the order in which to change parts for a single cylinder misfire.

So, its a difference that makes no difference IMHO.

"Wasted spark" just means a cylinder receives a spark on the induction stroke where it does not serve any purpose (ie it is wasted), it makes for potentially a simpler/cheaper ignition system.
 

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however my understanding is that the ECU still triggers them in pairs.
That is probably not right. There are 6 IIRC prongs on coil pack connector vs 4 on those that waste spark. There would be no reason to have extra prongs if ECU commands in pairs. I had exactly the same issue and exactly with the 2nd cylinder (I dunno why). Changing coil pack with the one from AutoZone with lifetime warranty did the trick.
 

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change your coil pack dude.......if it happens after rain...i bet thats what it is ...due to its position it gets hairline cracks , and when it gets wet it'll arc to ground.....(the block)

i'd almost guarantee thats your issue
 

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Discussion Starter · #12 ·
An update: we tested the ignition coil by soaking it down with a water bottle while the motor was running. Nary a hiccup in the idle, so seemed likely that the coil was still intact.

Hubs changed the wires: we used this set, good for non-AEG engine, although similar is much cheaper at German Auto Parts (we needed it today). As for the infamous "ignition wire removal tool," we had decided just to buy it, as we had limited time to get this done today, but when my husband saw it and understood how it was supposed to work, his opinion was that it would save about 15 seconds/wire. Not worth $40. (FWIW, he did say it was a pain to get the old wires out; he still doesn't see how that tool would have helped much). I'm not sure what tool he used to remove the old wires, but I do know he did not need to remove the intake manifold and the whole operation took less than an hour.

When he removed the old wires, we noticed that the boot of the wire to spark plug #2 was crushed somehow; no idea how that happened but it looks clear that was the culprit.

Thanks for all the advice.

Car started up fine and ran well on a test drive, even with the pouring rain today. Fingers crossed that this solves the issue.
 

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Jitterbug
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Glad its sorted, crushed plug boots are mostly the result of using pliers to remove the boot (previous owner/shop).
 

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Discussion Starter · #14 ·
Well, I guess I didn't cross those fingers hard enough.

Car sat over the weekend: went to start it today (a reasonably dry, if humid day) and same problem. Same code: P0302. Turned it off, let it sit a minute. Turned it back on: started up fine and engine smoothed out beautifully. Let it run a few minutes. Turned off. Turned back on: same rough start, same choppy engine, same code. Soaked the ignition coil down very well with WD40, let it sit about 10 minutes. Started up again: no difference.

I suppose I should just replace the coil, but I hate to spend $200 on one if that is not the problem, and none of the diagnostic tests are pointing to the coil. Could there be an internal problem with the coil that isn't related to a crack in the casing? Or should I start looking at other things? MAF maybe?

Sigh. In the meantime, I have to rent a car for a trip to Boston. Another $200 down the drain...
 

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educate me some....what was the purpose of soaking the coil pack with wd-40?

if you still ahve a misfire, i'd be looking at your fuel injectors
 

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Discussion Starter · #16 ·
Droid,

As I understand it, ignition coil issues often happen when it is wet or humid out; small cracks in the coil get wet, then the spark generated in the coil is not transferred to the spark plugs, but instead follows the water and grounds out.

Soaking the coil in WD-40 is a way to draw the water out of the coil, drying it out and improving performance. It is somewhat of a diagnostic tool to assess coil issues.

Kaela
 

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Did you ever figure out cyl 2 misfire issue?

I know this post is really old but I am having the exact issue with my 2003 VW Beetle 2.0. Did you ever discover the actual problem and solution? If you don't mind, could you email me at [email protected] with what you found out. It would be greatly appreciated! Thanks!
 
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