Codes P0305, p0301, and p0507, misfire?

2013 VOLKSWAGEN TIGUAN
143,000 MILES • 4 CYL • TURBO • 2WD • AUTOMATIC
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BHAMDOC1973
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It has constant check engine misfire. It's not coils. P0305 and p0301, as well as p0507.
Jan 18, 2024 at 8:58 AM
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STRAILER
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It seems like you may have a vacuum leak, I have seen the intake manifold crack and create a leak. I assume you have new spark plug, correct? Also, when the spark plugs were out what did they look like, were they all the same color?

P0305 and P0301: These are OBD-II trouble codes for cylinder misfires. P0305 indicates a misfire in cylinder 5, and P0301 indicates a misfire in cylinder 1.

P0507: This code indicates that the idle speed is higher than expected.

You can use this guide when the engine is cold to see if you can find a vacuum leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Check out the images (below). Please upload pictures or videos in your response of the problem so we can see what's going on.
Jan 18, 2024 at 11:26 AM
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BHAMDOC1973
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I ordered a new set of plugs and coils. Some coils are dirty and have minor oil. No oil in spark plug holes. There is a lot of fuel on cylinder 4 and it's wet, but they all look so old. I also suspect a leak like you said as am hearing a noise that is similar to cat leaks, similar to what a hemi motor sounds like when the exhaust bolt breaks on it.
Jan 18, 2024 at 11:52 AM
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STRAILER
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sounds good, on #4 I would do a compression test in case it is low.

Check out this guide:

https://www.2carpros.com/articles/how-to-test-engine-compression

Please go over this guide and get back to us.
Jan 19, 2024 at 9:40 AM
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BHAMDOC1973
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All good except 4, has zero compression. Well dang, is it possible all the fuel caused a cylinder wash? How does a cylinder just lose all compression on these motors? Seen it several times.
Jan 19, 2024 at 10:10 AM
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STRAILER
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Yep, that will do it, I have seen the valve seats fall out the cylinder head or the exhaust valve get burnt due to extreme usage. We need to remove the cylinder head to be sure and fix the problem. The lower ends seem to be pretty good so I don't think it would be the piston rings. How did the engine sound when it was running? Ticking, knocking? Here is how to remove the cylinder head. Check out the images (below). Please upload pictures or videos in your response to the problem so we can see what's going on.
Jan 19, 2024 at 10:27 AM
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BHAMDOC1973
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Minor ticking that is similar to an exhaust leak. But once you rev it sounds fine. And no smoke.
Jan 19, 2024 at 10:29 AM
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STRAILER
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Yep, it sounds like the valve seat fell out of the cylinder head, please look at the post above for instructions on how to remove the cylinder head to confirm.
Jan 19, 2024 at 10:41 AM
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BHAMDOC1973
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Is there a way to tell when pulling the valve cover off?
Jan 19, 2024 at 10:47 AM
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STRAILER
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Yes, if you remove the valve cover one of the valve stems will be slightly lower than the others.
Jan 21, 2024 at 9:34 AM
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BHAMDOC1973
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I am not sure what that would look like, can you get me a picture of how it should look like?
Jan 21, 2024 at 9:38 AM
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STRAILER
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Sorry I don't have a picture.
Jan 21, 2024 at 9:48 AM