Extreme power loss on c63s
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Junior Member
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2018 C63S Sedan
Extreme power loss on c63s
I recently got a muffler delete on my c63s w205 and am experiencing lots of power loss. I can’t even get up to 500hp. The computer is showing I barely get to 300hp. Is this cause I don’t have enough back pressure
Member
Joined: Aug 2019
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From: Dallas, TX
2020 Range Rover Sport P525 Dynamic
Will need more info than that man…did you get your valves removed or are any of them unplugged? Also did you anything to your cats as well?
Last edited by C63_01; Jul 7, 2021 at 05:31 PM.
Thread Starter
Junior Member
Joined: May 2021
Posts: 16
Likes: 2
2018 C63S Sedan
Thread Starter
Junior Member
Joined: May 2021
Posts: 16
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2018 C63S Sedan
MBWorld Fanatic!
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2019 AMG GT R
the muffler has 2 valves so if you did a muffler delete without plugging in a valve simulator you are in limp mode most likely
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Super Member
Joined: May 2011
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From: Vancouver
2018 e63s edition 1
You need a 50 dollar pair of awe valve simulators as long as your car is pre facelift (not sure if they make them for facelift models now). They plug into the wiring harness that uses to plug into the wiring for each valve on your muffler. Search the forum for the proper procedure to do it (is. Car asleep, etc)
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Thread Starter
Junior Member
Joined: May 2021
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2018 C63S Sedan
MBWorld Fanatic!
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2005 E55
Are u tuned or stock? I just put my stock tune on my car to get a recall done and it's slow as a prius lol if I were to open up the exhaust now it would feel even slower. It could be a loss in torque with less back pressure.
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Joined: Aug 2019
Posts: 82
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From: Dallas, TX
2020 Range Rover Sport P525 Dynamic
You would have to scan it with Xentry (dealership can do it). However, if its only showing 300-350hp its most likely due to limp mode. My car when i changed my exhaust was having trouble getting to 503hp but was still in the high 400s so i knew it wasnt in limp mode. However something was causing it reduce power by 5-10% and that was the soft code being throw by a missing valve (from going from an H-pipe to an X pipe that without center valve) which I plugged in with an AWE simulator.
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Joined: May 2011
Posts: 883
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From: Vancouver
2018 e63s edition 1
I can't even believe people are going back on this topic after how widely known this is on here. I had this setup, it's been talked about on multiple very long threads. your car is in a soft limp mode (no check engine light) where it won't build boost because it thinks your exhaust flaps are stuck closed and creating a blockage/decreased flow because the exhaust wiring is unplugged. 50 dollar awe sims is all it takes to fix this. This IS your problem.
Edit: Here...
https://mbworld.org/forums/c63-c63s-...ulators-3.html
You absolutely don't want back pressure in a turbo car. Ar the point where the exhaust is actually exiting the car you want it leaving as least restrictive and fast as possible.
Edit: Here...
https://mbworld.org/forums/c63-c63s-...ulators-3.html
Last edited by ShaneN.; Jul 9, 2021 at 07:23 AM.
Newbie
Joined: Aug 2024
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C63S 2017
You would have to scan it with Xentry (dealership can do it). However, if its only showing 300-350hp its most likely due to limp mode. My car when i changed my exhaust was having trouble getting to 503hp but was still in the high 400s so i knew it wasnt in limp mode. However something was causing it reduce power by 5-10% and that was the soft code being throw by a missing valve (from going from an H-pipe to an X pipe that without center valve) which I plugged in with an AWE simulator.
Three weeks ago I did a backbox delete on my 17’ C63S. After the delete my HP Gauge stopped going all the way to 500+ hp and only showed ~460 hp max. Next day the car went into limp mode (no code thrown or CEL) just power limited to 350hp max! Started investigating on forums about this. And is a common issue and a headache to solve. Happens because the cars senses the exhaust valves arent working properly and sends the car into limp mode.
Went with a local tuner so that they could code out the exhaust flaps, to see if that could solve the problem! It did to a certain extent. The car was out of limp mode, however the power was still only reaching 460hp and i could feel the lack of punch. Kept digging into it and found out the car even with the flaps coded out, sends the car into a Soft Limp Mode which cant be detected by normal scanners! Only Xentry system of MB can detect it. Been dealing with this problem for 3 weeks now. I reverted my backbox to stock. And still just shows 460hp on my HP Gauge! I asked a local mechanic with xentry to check it out and says no code shows in xentry! I dont know what to do. Maybe take it to the MB dealer? I took it to a dyno and showed 503hp however my HP Gauge inside the car only goes up to 460HP.
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Joined: Aug 2024
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C63S 2017
How does the soft code appears in Xentry? How can I delete the soft code! I did a muffler delete and now my car is only showing 460HP, I reverted the muffler delete and installed the stock backbox with its valves, however the car still showing only 460HP in the dynamic engine graph of the car!
