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Yesterday in traffic I get the CEL flashing for a bit then it stays on solid. Car began to shake and idle roughly.
After leaving the car overnight, I turned the car on and there was no issue at all. Idle was good, performance was normal.
Today I drive it and it starts to shake again and CEL comes on. Then I leave the car idling for about 5 minutes in Neutral and the idle returned to normal and car was good again
I'm getting a P0305 Misfire on Cylinder 5.
I don't know what it is and I have it booked in to the workshop on Monday morning. My question is, if it was a bad coil or spark plug, wouldn't the rough idle be constant and not "fix" itself up after letting it idle for a while?
If anyone has experienced the same thing or has any idea what this is, I'm all ears.
Thanks fellas.
Last edited by Jimmy_c63s; Mar 14, 2020 at 10:49 AM.
Reason: Info added
I've been having a similar issue. Intermittent rough idle (like a misfire) and it has thrown the CEL a couple times. After shutting the car down and leaving it off for a while, the code clears itself. The car runs fine otherwise, with no discernible loss in performance. I had the dealership check into it and they claimed there was no code stored.
Yesterday in traffic I get the CEL flashing for a bit then it stays on solid. Car began to shake and idle roughly.
After leaving the car overnight, I turned the car on and there was no issue at all. Idle was good, performance was normal.
Today I drive it and it starts to shake again and CEL comes on. Then I leave the car idling for about 5 minutes in Neutral and the idle returned to normal and car was good again
I'm getting a P0305 Misfire on Cylinder 5.
Sorry to hear your having issues...never fun.
But remind me...does your car have any performance mods???
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
Originally Posted by SJGetsome
I've been having a similar issue. Intermittent rough idle (like a misfire) and it has thrown the CEL a couple times. After shutting the car down and leaving it off for a while, the code clears itself. The car runs fine otherwise, with no discernible loss in performance. I had the dealership check into it and they claimed there was no code stored.
That's not good. Strange! Sounds like it could be our plugs or coils.
Originally Posted by W205-S
Sorry to hear your having issues...never fun.
But remind me...does your car have any performance mods???
Hey brother! Yep it sucks big time. I have no mods just stock (boring) and the spark plugs haven't been changed before.
I'm at 55,000km (35,000 miles) on the odo. Man I hope it's not some big engine problem as my warranty ended 3 months ago.
The misfire is always showing on cylinder 5. No other codes!
Hey brother! Yep it sucks big time. I have no mods just stock (boring) and the spark plugs haven't been changed before.
I'm at 55,000km (35,000 miles) on the odo. Man I hope it's not some big engine problem as my warranty ended 3 months ago.
The misfire is always showing on cylinder 5. No other codes!
Well let's just hope it is some computer glitch and nothing serious.
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
Originally Posted by W205-S
Well let's just hope it is some computer glitch and nothing serious.
Keep us informed and Good Luck my friend!
Thank you mate, will update this thread in case others have this issue!
Originally Posted by NYCSoiL
I had the same issue once, it was a bad gas.
Now that you've mentioned it I was thinking it could also be this because the misfire resolved itself when I left the car idling for 10 minutes but happened again later on when I drove it
Coincidentally I have just filled up a full tank. Can I ask you, did your misfire happen on just one cylinder? How did you fix yours? Would letting the car idle for 30 minutes be ok?
That's not good. Strange! Sounds like it could be our plugs or coils.
That's my thought as well. I'm still under the factory warranty so I'm hoping to get the dealership to handle changing the plugs and/or coils so I don't have to come out of pocket for it. My car is bone stock.
Not an uncommon issue and is usually coil(s) and/or plug(s). There has been at least one coil-pack recall ... then there are unusual plug issues, like this one:
Thank you mate, will update this thread in case others have this issue!
Now that you've mentioned it I was thinking it could also be this because the misfire resolved itself when I left the car idling for 10 minutes but happened again later on when I drove it
Coincidentally I have just filled up a full tank. Can I ask you, did your misfire happen on just one cylinder? How did you fix yours? Would letting the car idle for 30 minutes be ok?
It was a first gas station stop in the USA after driving the car in Europe on Shell 100. Floored the car merging into the highway, it started shaking with the check engine light on so I took the nearest exit, restarted the car and everything is still fine after driving the car for 9 months now. I waited till the last drop of that bad gas, filled the car up at the different gas station. Misfire happened on 2 cylinders
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
Originally Posted by SJGetsome
That's my thought as well. I'm still under the factory warranty so I'm hoping to get the dealership to handle changing the plugs and/or coils so I don't have to come out of pocket for it. My car is bone stock.
Is yours intermittent? Like, at times it runs okay and other times CEL comes up? Or is it just permanent CEL for you and always rough?
Originally Posted by user33
Not an uncommon issue and is usually coil(s) and/or plug(s). There has been at least one coil-pack recall ... then there are unusual plug issues, like this one: https://www.youtube.com/watch?v=M7WXHEsuh_Q
... that one caused misfire codes mostly when idling but also sometimes when under WOT above 6K RPM.
Yeah that's a bad plug for sure, thanks for the video.
Originally Posted by NYCSoiL
It was a first gas station stop in the USA after driving the car in Europe on Shell 100. Floored the car merging into the highway, it started shaking with the check engine light on so I took the nearest exit, restarted the car and everything is still fine after driving the car for 9 months now. I waited till the last drop of that bad gas, filled the car up at the different gas station. Misfire happened on 2 cylinders
Thanks man. Can I ask you, during the bad fuel incident, were the two misfires on the exact same two cylinders all the time?
@Jimmy_c63s bro its your plug, I had the same issue when i took mine to Mercedes before Dyne Performance blew up my turbos. Your engine will be fine its over engineered ... just change all the plugs not just that one ..
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
Originally Posted by Haji3978
@Jimmy_c63s bro its your plug, I had the same issue when i took mine to Mercedes before Dyne Performance blew up my turbos. Your engine will be fine its over engineered ... just change all the plugs not just that one ..
SOLVED!
Spot on brother, it was a bad coil which also zapped the spark plug!
The bad spark plug was actually caused by a failing coil so they replaced the bad coil and all the plug now she's back to her old self again (thank you lord). Cheers to all of you who took time and posted here.
PS: For anyone looking for it the coil part no. for C63s M177 4.0 V8 it's A1779069500 they cost over $600 AUD each brand new from Mercedes and our engines have 4 x coils in total - one coil on every two spark plugs.
You can get them cheaper (used) on ebay if you really need them urgently but I wouldn't get a second hand one especially if you are tuned.
Last edited by Jimmy_c63s; Mar 4, 2022 at 09:55 PM.
I've been having a similar issue. Intermittent rough idle (like a misfire) and it has thrown the CEL a couple times. After shutting the car down and leaving it off for a while, the code clears itself. The car runs fine otherwise, with no discernible loss in performance. I had the dealership check into it and they claimed there was no code stored.
I also have encountered the same problem today misfire cylinder 5
4 months out of warranty 52500 kms
Yesterday in traffic I get the CEL flashing for a bit then it stays on solid. Car began to shake and idle roughly.
After leaving the car overnight, I turned the car on and there was no issue at all. Idle was good, performance was normal.
Today I drive it and it starts to shake again and CEL comes on. Then I leave the car idling for about 5 minutes in Neutral and the idle returned to normal and car was good again
I'm getting a P0305 Misfire on Cylinder 5.
I don't know what it is and I have it booked in to the workshop on Monday morning. My question is, if it was a bad coil or spark plug, wouldn't the rough idle be constant and not "fix" itself up after letting it idle for a while?
If anyone has experienced the same thing or has any idea what this is, I'm all ears.
Thanks fellas.
I also have encountered the same problem today misfire cylinder 5
4 months out of warranty 52500 kms
Hey guys hope everyone is staying safe, I have a 2018 Mercedes c63s with just over 25k miles on it. The car has had the issue at stage 1 but more recently I just added downpipes so I guess u could call it a stage 2 car. Installing my downpipes gave me a check engine light which lead me to plug in a scanner and among the 2 codes I got from the downpipes(PO420 and PO430). There was also a PO308 for a misfire on cylinder number 8 that was pending. Did changing all spark plugs and the one coil pack solve the issue for any of you guys, would appreciate the input
Hey guys hope everyone is staying safe, I have a 2018 Mercedes c63s with just over 25k miles on it. The car has had the issue at stage 1 but more recently I just added downpipes so I guess u could call it a stage 2 car. Installing my downpipes gave me a check engine light which lead me to plug in a scanner and among the 2 codes I got from the downpipes(PO420 and PO430). There was also a PO308 for a misfire on cylinder number 8 that was pending. Did changing all spark plugs and the one coil pack solve the issue for any of you guys, would appreciate the input
Lots of these tuners seem to suggest fresh plugs, and more often. I'd honestly just do plugs regardless if you need them or not and go from there. I'm at 18k miles and will be tuning next week, I plan on doing plugs shortly after. Maybe you can convince your service advisor to do fresh plugs under warranty because you're misfiring (even though you're tuned).
Lots of these tuners seem to suggest fresh plugs, and more often. I'd honestly just do plugs regardless if you need them or not and go from there. I'm at 18k miles and will be tuning next week, I plan on doing plugs shortly after. Maybe you can convince your service advisor to do fresh plugs under warranty because you're misfiring (even though you're tuned).
gotcha and yes I do plan to take it in to the dealer, am not worried about it being covered under warranty as a cleared all the work the with service advisor beforehand, he’s the one who twisted my arms to put downpipes on it . Hopefully that will take care of the problem
thank you.
I have a 2017 C63S with 38K—Had the exact same misfire happen but CEL only came on when in Sport + mode. If I turned off and started again in comfort mode, it would run like normal. I’m getting reading from cylinder 4 for misfire but had to take the car to them while having CEL still on. Ill have them replace the spark-plugs for sure, but they were thinking coil packs as well possibly… would extended warranty cover that?!
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
Originally Posted by PistolPete C63S
I have a 2017 C63S with 38K—Had the exact same misfire happen but CEL only came on when in Sport + mode. If I turned off and started again in comfort mode, it would run like normal. I’m getting reading from cylinder 4 for misfire but had to take the car to them while having CEL still on. Ill have them replace the spark-plugs for sure, but they were thinking coil packs as well possibly… would extended warranty cover that?!
Yeah you're covered mate. Get the dealership to sort it out asap.
The rough idle occurs every time I drive the car, but is intermittent through the drive. The CEL comes up far less. Maybe only a handful of times.
As an update to the issue I was having, it finally threw a CEL that stayed on that I could have diagnosed and it was a misfire in cylinder 7. I changed all the plugs the next day and that resolved the issue. Turned out to be a failure of the Cylinder 7 plug that triggered the CEL. The ceramic broke and dropped down, covering the electrode. Before it finally gave way I assume it was loose and causing the intermittent issue I was having, but hadn't completely failed yet as there was no CEL.
Could have turned out a lot worse. If you're having a similar rough idle issue, start by changing and inspecting the plugs and that will likely resolve the problem. And if not, you'll have fresh plugs and know it's likely a bad coil.
Had a misfire in cylinder 1 a few months ago, had the coils and all spark plugs changed. Last week on my way to the dealer for a service had another misfire but this time it was no where near as bad as the first time (car didn't shake much then flashing to solid cel). Dealer did a scan and didn't find codes relating to a misfire, only codes relating to "off timing".
Both misfires happened in sport plus, once in heavy stop go traffic and this time cruising on highway.
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
How did you go?
Originally Posted by dctwc63s
Had a misfire in cylinder 1 a few months ago, had the coils and all spark plugs changed. Last week on my way to the dealer for a service had another misfire but this time it was no where near as bad as the first time (car didn't shake much then flashing to solid cel). Dealer did a scan and didn't find codes relating to a misfire, only codes relating to "off timing".
Both misfires happened in sport plus, once in heavy stop go traffic and this time cruising on highway.
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... just change all the plugs not just that one 
