C32 AMG, C55 AMG (W203) 2001 - 2007

Misfire at higher rpms

Old Aug 24, 2021 | 02:41 AM
  #1  
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Mercedes c32 2002
Misfire at higher rpms

Hello everyone, it is my first post here I been reading on this website and I didn't really find a solution to my problem. So i have a mercedes c32 2002 with 240kms on it, when I bought it it have a front damage and a some sort of misfire, so I thought it could be the coils or spark plugs, so first thing I did was to change the spark plugs and coils I took it for a test drive and when ever I push it and the rpms reach about 4 thousand rpm it would not shift and it would misfire so I would pull over turn the car off then back on then it would drive just fine. I took it to more than 1 mechanic and they all said a different thing, one said vacuum leak and he I told him to fix but still had the same problem, the other one said fuel filter but when I changed it the car had a better pick up but still had the same problem, so I decided to take it to the dealership so they can tell me the final answer, they said it was the throttle body, so I changed it and still has the same problem. So now they are telling me the timing chain or the catalytic converter, and plus now I have a code for the cats. Any idea on what I should do any advice?. Thanks you for reading
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Old Aug 24, 2021 | 05:50 AM
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Erik C32's Avatar
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'02 C32 (S203)
Originally Posted by Mike_c32
Hello everyone, it is my first post here I been reading on this website and I didn't really find a solution to my problem. So i have a mercedes c32 2002 with 240kms on it, when I bought it it have a front damage and a some sort of misfire, so I thought it could be the coils or spark plugs, so first thing I did was to change the spark plugs and coils I took it for a test drive and when ever I push it and the rpms reach about 4 thousand rpm it would not shift and it would misfire so I would pull over turn the car off then back on then it would drive just fine. I took it to more than 1 mechanic and they all said a different thing, one said vacuum leak and he I told him to fix but still had the same problem, the other one said fuel filter but when I changed it the car had a better pick up but still had the same problem, so I decided to take it to the dealership so they can tell me the final answer, they said it was the throttle body, so I changed it and still has the same problem. So now they are telling me the timing chain or the catalytic converter, and plus now I have a code for the cats. Any idea on what I should do any advice?. Thanks you for reading
Look inside your cats to see if they are blocked. I had the same thing and that resulted in misfires on 1 specific cylinder (which theoretically doesn’t make sense) at higher RPMs / load. In my case, the root cause for the failed cat was a leaking chargecooler.
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Old Aug 24, 2021 | 10:18 PM
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Mercedes c32 2002
Originally Posted by Erik C32
Look inside your cats to see if they are blocked. I had the same thing and that resulted in misfires on 1 specific cylinder (which theoretically doesn’t make sense) at higher RPMs / load. In my case, the root cause for the failed cat was a leaking chargecooler.
Ya same with mine I only have a misfire on bank1, I'm trying to find a shop that would remove the cats and just put a straight pipe since the car is old and I don't want to put too much money on it
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Old Aug 24, 2021 | 11:44 PM
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'02 C32 (S203)
The cheapest way of ‘solving’ a blocked cat is emptying it. If you can remove the section then you can empty it without cutting or welding.

IF you decide to do it, then only do the secondary cats because removing the primary cats will give you errors.


Last edited by Erik C32; Aug 25, 2021 at 12:54 AM.
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Old Aug 25, 2021 | 02:49 AM
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From: Melbourne
2002 C32 AMG (SOLD), 2004 C55 AMG
Originally Posted by Erik C32
The cheapest way of ‘solving’ a blocked cat is emptying it. If you can remove the section then you can empty it without cutting or welding.

IF you decide to do it, then only do the secondary cats because removing the primary cats will give you errors.

https://youtu.be/FhiW_t-rgak
Can also get a tune/code off the O2 sensors to remove the CEL caused by no cats.
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Old Aug 26, 2021 | 08:07 PM
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Mercedes c32 2002
So I removed the cats, the cat that one the side where the misfire happens is empty and the secondary cats were clogged, so now the car misfires at 6 thousands rmp and something new just happened the abs light would come on and eps bas and other wired lights comes on and it would not shift at all and the speed gauge would go down to zero then back up, any ideas what's happening?
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Old Aug 26, 2021 | 08:30 PM
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From: Melbourne
2002 C32 AMG (SOLD), 2004 C55 AMG
Originally Posted by Mike_c32
So I removed the cats, the cat that one the side where the misfire happens is empty and the secondary cats were clogged, so now the car misfires at 6 thousands rmp and something new just happened the abs light would come on and eps bas and other wired lights comes on and it would not shift at all and the speed gauge would go down to zero then back up, any ideas what's happening?
Did you remove the secondary cats too? And did you remove both side cats or just one?

Scan your car and see what codes come up but you cannot remove your primary cats without getting a tune or coding off your O2 sensors as it will throw codes and possibly freak out.
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Old Aug 26, 2021 | 09:06 PM
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Mercedes c32 2002
Originally Posted by alb3rtt
Did you remove the secondary cats too? And did you remove both side cats or just one?

Scan your car and see what codes come up but you cannot remove your primary cats without getting a tune or coding off your O2 sensors as it will throw codes and possibly freak out.
ya i removed all 4.
I think your right, because I tried to reset the transmission system and then this happened right away, but it still misfires and like 6 thousand rpms and I don't want to tune it until I fix it
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