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Cannot track down this misfire

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Old Aug 12, 2020 | 09:42 PM
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Escott16
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2001 w203
Cannot track down this misfire
Check engine light when wide open throttle above 4500 rpm. Code p0304 cylinder 4 misfire.

Replaced

-spark plugs

-mass airflow sensor

-valve cover gasket passenger side (along cyc 1,2,3)(needed done while doing this)

-tested fuel pressure and get proper pressure

-swapped coil pack and fuel injector with another cylinder and still constant misfire cylinder 4
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Old Aug 13, 2020 | 05:13 PM
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Russell Ormerod
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A good start would be to tell us what engine you taking about!
also some history of how this misfire started. Previous work done?
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Old Aug 13, 2020 | 05:22 PM
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2001 w203
I am sorry didn’t even think to, it’s a 2001 C320 with 120k miles and it kind of came out of no where I noticed it trying to merge fast one day erased the code and the car runs fine and only does the misfire when above 4500rpm and I noticed my valve covers leaking oil into spark plugs so I changed the plugs and gasket hoping it was related but it wasn’t
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Old Aug 14, 2020 | 12:14 PM
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Any work ever been done on the gearbox? Flexplate? Gearbox removed maybe?
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Old Aug 14, 2020 | 12:30 PM
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2001 w203
No work outside what I’ve mentioned
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Old Aug 14, 2020 | 12:53 PM
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Russell Ormerod
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Okay. For that kind of misfire.. do you have DAS? Do a default initialization and recheck
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Old Aug 14, 2020 | 01:10 PM
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2001 w203
I do not. Just a scanner
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Old Aug 14, 2020 | 05:56 PM
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Russell Ormerod
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Find someone with DAS
also you need scope the crank signal. I would like to see how it looks
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Old Aug 14, 2020 | 06:10 PM
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2001 w203
Is the scope thing something I can do. I have a decently equipped garage
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Old Aug 18, 2020 | 03:59 PM
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Then post a print out of the oscilloscope signal from the crank sensor at idle speed. Showing 1 revolution of the crankshaft
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