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I have a jetta 2.5L 2006 and I have a P0305 check engine. The code says cylinder 5 misfire detected and the car shakes badly on iddle.

I did have a look at the coil packs and they look all good and the spark plugs were changed last year.

As a tests, I moved all the coil packs to see if I would get another error code but the P0305 for cylinder 5 reappeared.

Is there something simple I can try before bringing my car to a garage?

Thank you

Note: This all started after I jumped start my car

Update: I haven't checked the spark plugs yet because I don't have the tool but this morning I got a new check engine code. P0300 Random/multiple cylinder misfire detected

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    Change a spark plug as you did a coil. Same reasoning. – Pᴀᴜʟsᴛᴇʀ2 Aug 25 '16 at 23:05
  • Good idea! I will try that – Marc Aug 25 '16 at 23:18
  • I'm assuming this is the gasoline engine. Another cylinder-specific item worth checking is the fuel injector. Swap it with another injector and see if the code follows the injector. – Zaid Aug 26 '16 at 2:07
  • First thing I'd do is remove the spark plug from cylinder 5 and visually inspect it. Also inspect that it was seated correctly. You could swap cylinder 5 coil pack and plug with another cylinder and see if the fault moves to the other cylinder or stays on cylinder 5. Can you explain what "boosted my car" means please? – Steve Matthews Aug 26 '16 at 7:31
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    So I see. Compression test would be next on my list. If that checks out, check the wiring and fuses. The jump could have damaged the signal to the coil pack or something? – Steve Matthews Aug 26 '16 at 12:23
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If the coil pack on cylinder 5 started to malfunction then even swapping the coils around could still give the same trouble code because when a coil makes a plug miss a few sparks generally that spark plug will have gotten covered in fuel and fouled out basically. Check and clean or replace that spark plug then swap the coils around to see what the new outcome is. Also, if you don't reset that cylinder 5 code then it's gonna continue to show up on your scanner anyway. The scanner should have an ERASE CODES option which is necessary to do before continuing the process. In my experiences you're best bet is to go ahead and replace that coil and plug and reset the trouble codes, and I would recommend changing out the others before too long because the older ones are gonna struggle to keep up with the voltage that the one will be generating because all coils and plugs slowly get weaker over time.

  • Perfect! I will try that. I did reset the code though – Marc Aug 30 '16 at 13:41
  • I'm really thinking that plug is fouled out so bad it's not allowing any fire thru it. Which in that case would most likely mean that coil is fried. It's very common though, have seen it a million times with my customers and I follow my same steps each time and like a charm it takes care of it. – TRIGGA Aug 30 '16 at 13:44
  • If a coil is fried, what would it look like? They looked pretty good and clean – Marc Aug 30 '16 at 14:50
  • So I would have to change the spark plug and the coil pack? – Marc Aug 30 '16 at 14:51
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    Shouldn't be related, sounds like a vacuum leak somewhere. With the car running try to listen around the engine for a small hissing sound. Wouldn't hurt to spray clean your mass air flow sensor with MAF cleaner spray as well because it could be dirty and getting a faulty air flow reading so it's not telling the computer the proper air/fuel mixture to make. – TRIGGA Sep 12 '16 at 2:10
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I have just worked on an 05 Jetta with the 2.5 having this misfire issue. Ultimately what I found was that the rubber insulator inside the coil pack where the spark plug terminal meets the spark plug, one had cracks and another had chunks out of it. Also, the metal sleeve of the coil pack was either too close to the hex drive of the spark plug or even making contact with it, causing the spark to merely go to the spark plug base. Solution: I trimmed the metal sleeve off with a tin snips to even with the rubber insulator and wrapped the entire length of the metal sleeve with a layer of electrical tape. So far no more misfiring issues. Hope this helps some one out there. Ive been frustrated with this thing for about 5 weeks now.

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