2012 CLS 63 Misfire
Thread Starter
Junior Member
Joined: Sep 2017
Posts: 23
Likes: 1
From: Colorado
2012 CLS 63 AMG, GL450 2017 C300 4matic
2012 CLS 63 Misfire
Hi, looking for some insight and help with the flowing issue;
2012 CLS 63 ( has Weistec ECU Tune, cats only, all removed from cats back)
Constant misfire at idle (PO305) on # 5. Have replaced the plugs, the coil, and a new injector yesterday. (Done by local repair shop that specializes in MB, they have been very helpful and the owner has 25+ plus years experience at a MB Dealer). Car runs fine on the highway at all speeds, rough and intermittent idle when you pull up to traffic light.
Does not seem to use use any more oil than normal. Took it to the 1/4 mile track here on Wednesday (5800 feet above sea level), street tires, RWD, and it will run a 11.6 (best) to 11.9 to low 12s (not very consistent). CEL came on and code PO305 from a inexpensive reader I have.
Repair shop is struggling to find the issue and I do not want to keep replacing part after part. They think maybe a valve, scored cylinder?? Very good people there and they are trying to help, but has us all baffled. Any help would be very much appreciated. Thank you.
2012 CLS 63 ( has Weistec ECU Tune, cats only, all removed from cats back)
Constant misfire at idle (PO305) on # 5. Have replaced the plugs, the coil, and a new injector yesterday. (Done by local repair shop that specializes in MB, they have been very helpful and the owner has 25+ plus years experience at a MB Dealer). Car runs fine on the highway at all speeds, rough and intermittent idle when you pull up to traffic light.
Does not seem to use use any more oil than normal. Took it to the 1/4 mile track here on Wednesday (5800 feet above sea level), street tires, RWD, and it will run a 11.6 (best) to 11.9 to low 12s (not very consistent). CEL came on and code PO305 from a inexpensive reader I have.
Repair shop is struggling to find the issue and I do not want to keep replacing part after part. They think maybe a valve, scored cylinder?? Very good people there and they are trying to help, but has us all baffled. Any help would be very much appreciated. Thank you.
Thread Starter
Junior Member
Joined: Sep 2017
Posts: 23
Likes: 1
From: Colorado
2012 CLS 63 AMG, GL450 2017 C300 4matic
CLS 63 Misfire UPDATE
UPDATE
Issue got worse, car started to vibrate badly, no power at all (limp mode?) CEL flashing. Stopped and had it towed to the authorized MB dealer here in town. They pulled #5 and there was a obvious issue. (See pic of #6 and #5 Plug)
Replaced all 8 plugs again, as they believed that the plugs were significantly more than a few months old. Misfire gone, smooth idle, took it to the track that night and ran a 11.67 at 5800 feet, stock all season Yokahoma tires, RWD. Power was like when it was new! Smoked a Hellcat and that is always enjoyable.
Issue got worse, car started to vibrate badly, no power at all (limp mode?) CEL flashing. Stopped and had it towed to the authorized MB dealer here in town. They pulled #5 and there was a obvious issue. (See pic of #6 and #5 Plug)
Replaced all 8 plugs again, as they believed that the plugs were significantly more than a few months old. Misfire gone, smooth idle, took it to the track that night and ran a 11.67 at 5800 feet, stock all season Yokahoma tires, RWD. Power was like when it was new! Smoked a Hellcat and that is always enjoyable.
Member
Joined: Jan 2015
Posts: 146
Likes: 6
From: Georgia
2010 S550 + 2014 CLS63 + 1993 300zx TT + 2014 Pathfinder + 2013 Hyundai Sanata
UPDATE
Issue got worse, car started to vibrate badly, no power at all (limp mode?) CEL flashing. Stopped and had it towed to the authorized MB dealer here in town. They pulled #5 and there was a obvious issue. (See pic of #6 and #5 Plug)
Replaced all 8 plugs again, as they believed that the plugs were significantly more than a few months old. Misfire gone, smooth idle, took it to the track that night and ran a 11.67 at 5800 feet, stock all season Yokahoma tires, RWD. Power was like when it was new! Smoked a Hellcat and that is always enjoyable.
Issue got worse, car started to vibrate badly, no power at all (limp mode?) CEL flashing. Stopped and had it towed to the authorized MB dealer here in town. They pulled #5 and there was a obvious issue. (See pic of #6 and #5 Plug)
Replaced all 8 plugs again, as they believed that the plugs were significantly more than a few months old. Misfire gone, smooth idle, took it to the track that night and ran a 11.67 at 5800 feet, stock all season Yokahoma tires, RWD. Power was like when it was new! Smoked a Hellcat and that is always enjoyable.
Super Member
Joined: Jul 2007
Posts: 636
Likes: 3
From: Orange County, Ca
C350
I just picked up a used 2012 CLS63 with 44K miles on it from Carmax and had a car shaking issue this morning while as a stop light. I thought it may have been the start/stop feature but it was very noticable. It has only happened once so far, and there were no warning messages. I hope this isnt a problem with the car, any thoughts? Maybe misfire?
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Out Of Control!!
Joined: Jun 2004
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2014 E63S; AMS 100 octane ECU dyno tune; EDOK TCU tune; BB intakes; sprintbooster
I just picked up a used 2012 CLS63 with 44K miles on it from Carmax and had a car shaking issue this morning while as a stop light. I thought it may have been the start/stop feature but it was very noticable. It has only happened once so far, and there were no warning messages. I hope this isnt a problem with the car, any thoughts? Maybe misfire?
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Super Member
Joined: Jul 2007
Posts: 636
Likes: 3
From: Orange County, Ca
C350
It’s not tuned that I know of, it seems very stock. I was reading on this forum and I’m wondering if I’m noticing the MCT transmission shudder? It only happens when the car is cold. I do have 5 days to return and I have the 5 year extended warranty.
Member
Joined: Nov 2011
Posts: 109
Likes: 5
From: DFW
W222 S550, W218 CLS63, W166 ML550, Titan, Sentra
Hey guys,
i had the same issue.....car has stage 2 EC tune, DPs, filters, and gapped down plugs.... misfire code came on and went into limp mode....the issue was running ****ty 93 gas from Exxon/7-11. Added a bottle of Octanium (only from Autozone) and filled with Shell 93 (purest form of all) and nothing has happen since. Cars runs like a champ with the +8 point booster.
i had the same issue.....car has stage 2 EC tune, DPs, filters, and gapped down plugs.... misfire code came on and went into limp mode....the issue was running ****ty 93 gas from Exxon/7-11. Added a bottle of Octanium (only from Autozone) and filled with Shell 93 (purest form of all) and nothing has happen since. Cars runs like a champ with the +8 point booster.
