W211 AMG Discuss the W211 AMG's such as the E55 and the E63

Bad Misfire on high RPM

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Old Feb 4, 2023 | 01:48 PM
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2003 CL55 AMG
Bad Misfire on high RPM

UPDATE::: problem fixed with 8 brand new coil packs and plug wires. Car runs stronger than ever.

I have a problem.. 2003 55. my car runs fine with lower RPM just cruising but as soon as I jump on it it sputters, backfires, and then misfires badly to the point where it has no power. It feels like its heat soaked but this will happen regardless of outside temperature and on the very first pull. Ive attached a picture of the codes it throws. I have magnaflow primary cats in place of the OEM (they split open a year ago) and I have no secondary cats or resonators just a straight pipe into stock mufflers. When it’s accelerating it sounds like it’s making popcorn lol, then it will also backfire even though I’m not running the RaceIQ pop tune just the normal tune. My exhaust guy said he doesn’t think the cats are blocked since there’s a ton of pressure coming out of the tips when i rev it. It has brand new o2 sensors and that didnt fix it so its not that. Also started doing this right before the 82mm and 630cc were installed, I assumed the new injectors wouldve fixed it but it didnt. Need help.



mods:
raceiq tune
77mm clutched pulley
vrp v2 heat exchanger
82mm throttle body
630cc bosch injectors
secondary cat + res delete

Last edited by maz55amg; Feb 9, 2023 at 02:49 PM.
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Old Feb 4, 2023 | 01:57 PM
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2006 CLS55 AMG, 2005 SLK 350 AMG
Originally Posted by maz55amg
I have a problem.. 2003 55. my car runs fine with lower RPM just cruising but as soon as I jump on it it sputters, backfires, and then misfires badly to the point where it has no power. It feels like its heat soaked but this will happen regardless of outside temperature and on the very first pull. Ive attached a picture of the codes it throws. I have magnaflow primary cats in place of the OEM (they split open a year ago) and I have no secondary cats or resonators just a straight pipe into stock mufflers. When it’s accelerating it sounds like it’s making popcorn lol, then it will also backfire even though I’m not running the RaceIQ pop tune just the normal tune. My exhaust guy said he doesn’t think the cats are blocked since there’s a ton of pressure coming out of the tips when i rev it. It has brand new o2 sensors and that didnt fix it so its not that. Also started doing this right before the 82mm and 630cc were installed, I assumed the new injectors wouldve fixed it but it didnt. Need help.

mods:
raceiq tune
77mm clutched pulley
vrp v2 heat exchanger
82mm throttle body
630cc bosch injectors
secondary cat + res delete
Monitor your fuel pressure at low and elevated RPM.
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Old Feb 5, 2023 | 03:14 AM
  #3  
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From: SOCAL
2004 E55
Your plugs are shot
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Old Feb 6, 2023 | 10:22 AM
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2006 E55
How many miles on your car? Could injector be clogged/not flowing correctly?

I also agree with the above, I'd start with spark then I'd check your O2s/cats (basing off your codes).

Last edited by ArmoE55; Feb 6, 2023 at 12:23 PM.
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Old Feb 6, 2023 | 12:19 PM
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W211 E63 AMG
clogged cats can cause this. if the exhaust system is fully flowing, this sounds like if the computer was pulling all timing.
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Old Feb 27, 2023 | 03:44 PM
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2017 C43 Coupe
Originally Posted by eightysixtuned
clogged cats can cause this. if the exhaust system is fully flowing, this sounds like if the computer was pulling all timing.
Would clogged cats also cause exhaust to smell like it's running rich? Still wouldn't throw codes?
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