Rough idle at startup? Before replacing your $600 throttle body, fix it for FREE!
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 250
Likes: 0
From: Charleston, SC
2005 C230K
Rough idle at startup? Before replacing your $600 throttle body, fix it for FREE!
Hey guys, hopefully this can help someone. As others have described, I was having a rough idle problem at startup, as well as the cruise control feeling "jumpy" as if it couldn't decide the exact RPM it wanted to stay at. I knew something was up but it wasn't really a big deal and after idling for 20 seconds or giving it some throttle, the shaking would go away. I replaced the oil, oil filter, air filter, fuel filter, and spark plugs, and then cleaned the front of the throttle body and some Chevron Techron, but the problem persisted.
After reading the entirety of this thread, I decided the TB (throttle body/actuator) had to be the source of my problems. I believe a new TB is about $600. Instead of immediately buying a new one and replacing it, I decided to see what I could do with my current one, so I took the TB out completely.
I found on the other side of the butterfly flap - the side facing the engine - there was a large amount of oil residue on the flap itself and around the opening. This is the side you can't see or access if you are just cleaning it from the front of the car. I didn't think to take pictures until after I had finished the job.
Anyway, I used some TB cleaner to get all the gunk off to where all you could see was shiny silver. Then I went to work on the internals. I figured since I was possibly going to have to buy a new TB anyway, it wouldn't really matter if I screwed this one up. I removed the 6 or so metal clips that held the black plastic piece on the side and then pulled the plastic piece straight out. The attached picture below is what it looks like with this plastic piece detached.
I used electrical contact cleaner to clean the carbon tracks and little metal "brushes" and then did a few light sprays on the gears and copper connectors and put the cover and clips back on. Note that if you do this, the plastic/nylon gear may fall off but you can just gently put it back in place. I would advise not actually touching the metal "brushes." I cleaned the carbon tracks with a shop towel and was able to get a good amount of black residue off.
I then re-installed the TB and had the smoothest start and idle I've ever felt while owning this car. It has been 2 weeks now and everything seems perfect, so I think I finally fixed the problem and avoided having to buy a new TB. Cruise control is now much smoother than it had been and even on cold mornings the starts and idles are flawless now.
So in summary, I would suggest saving yourself $600 by attempting to thoroughly clean your TB before buying a new one.
After reading the entirety of this thread, I decided the TB (throttle body/actuator) had to be the source of my problems. I believe a new TB is about $600. Instead of immediately buying a new one and replacing it, I decided to see what I could do with my current one, so I took the TB out completely.
I found on the other side of the butterfly flap - the side facing the engine - there was a large amount of oil residue on the flap itself and around the opening. This is the side you can't see or access if you are just cleaning it from the front of the car. I didn't think to take pictures until after I had finished the job.
Anyway, I used some TB cleaner to get all the gunk off to where all you could see was shiny silver. Then I went to work on the internals. I figured since I was possibly going to have to buy a new TB anyway, it wouldn't really matter if I screwed this one up. I removed the 6 or so metal clips that held the black plastic piece on the side and then pulled the plastic piece straight out. The attached picture below is what it looks like with this plastic piece detached.
I used electrical contact cleaner to clean the carbon tracks and little metal "brushes" and then did a few light sprays on the gears and copper connectors and put the cover and clips back on. Note that if you do this, the plastic/nylon gear may fall off but you can just gently put it back in place. I would advise not actually touching the metal "brushes." I cleaned the carbon tracks with a shop towel and was able to get a good amount of black residue off.
I then re-installed the TB and had the smoothest start and idle I've ever felt while owning this car. It has been 2 weeks now and everything seems perfect, so I think I finally fixed the problem and avoided having to buy a new TB. Cruise control is now much smoother than it had been and even on cold mornings the starts and idles are flawless now.
So in summary, I would suggest saving yourself $600 by attempting to thoroughly clean your TB before buying a new one.
Member
Joined: Nov 2008
Posts: 142
Likes: 6
From: New Orleans, LA
C230K Sedan
Yea everyone has the same problems once you get into high mileage. I had installed a new throttle and it still does it apparently. Its all that oil residue that builds up. And yes you are correct on cleaning it up. You will notice a great differences.. but then the oil continues leaking and building up in there... and the problem comes back in less then 2000 miles.
From what I found out no one hasn't really fixed this problem. Its leaking somewhere i'm guessing at the head gasket or supercharger gasket.
From what I found out no one hasn't really fixed this problem. Its leaking somewhere i'm guessing at the head gasket or supercharger gasket.
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 250
Likes: 0
From: Charleston, SC
2005 C230K
Yea everyone has the same problems once you get into high mileage. I had installed a new throttle and it still does it apparently. Its all that oil residue that builds up. And yes you are correct on cleaning it up. You will notice a great differences.. but then the oil continues leaking and building up in there... and the problem comes back in less then 2000 miles.
From what I found out no one hasn't really fixed this problem. Its leaking somewhere i'm guessing at the head gasket or supercharger gasket.
From what I found out no one hasn't really fixed this problem. Its leaking somewhere i'm guessing at the head gasket or supercharger gasket.
Super Moderator Alumni
Joined: Oct 2002
Posts: 8,692
Likes: 58
From: So Cal.
2019 GT3 RS, 2017 M3 30 Jahre
Just saw this now...
Thanks for sharing. How is your car running now?
The rough idle started for me again about 10k miles ago.
I just ordered a used throttle body and will be replacing my throttle body this weekend (this will be the third TB in the car). When I take out the TB, I'll check it out and clean it per your recommendations.
I can't believe this now $800 part is a wear item on this car.
Thanks for sharing. How is your car running now?
The rough idle started for me again about 10k miles ago.
I just ordered a used throttle body and will be replacing my throttle body this weekend (this will be the third TB in the car). When I take out the TB, I'll check it out and clean it per your recommendations.
I can't believe this now $800 part is a wear item on this car.
Junior Member
Joined: Jan 2011
Posts: 35
Likes: 0
C230 2003
The rough idle I've been experiencing is only happening from a cold start. It goes away as the car warms up. Today I completed doing the quick fix posted above. My throttle body was really filthy on the side that faces the engine. The portion of the throttle body that houses the electrical component was actually really clean and I probably didn't need to do that step but I wanted to try anything that could help.
Thanks! I'll report back in a couple weeks.
Thanks! I'll report back in a couple weeks.
Trending Topics
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 250
Likes: 0
From: Charleston, SC
2005 C230K
So it has been exactly 2 years since I thoroughly cleaned my TB with electrical contact cleaner and the symptoms are just now starting to return, so today I will be cleaning it again as described in my original post. Not sure if it's a coincidence that it's also just starting to get cold here.
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Junior Member
Joined: Feb 2015
Posts: 35
Likes: 6
W203 c180 2007
hi every body
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
send me whatsapp if u want to join MB group
00971506740840
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
send me whatsapp if u want to join MB group
00971506740840
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
Junior Member
Joined: Feb 2015
Posts: 35
Likes: 6
W203 c180 2007
vibration on red light with AC + gear D
Hey guys, hopefully this can help someone. As others have described, I was having a rough idle problem at startup, as well as the cruise control feeling "jumpy" as if it couldn't decide the exact RPM it wanted to stay at. I knew something was up but it wasn't really a big deal and after idling for 20 seconds or giving it some throttle, the shaking would go away. I replaced the oil, oil filter, air filter, fuel filter, and spark plugs, and then cleaned the front of the throttle body and some Chevron Techron, but the problem persisted.
After reading the entirety of this thread, I decided the TB (throttle body/actuator) had to be the source of my problems. I believe a new TB is about $600. Instead of immediately buying a new one and replacing it, I decided to see what I could do with my current one, so I took the TB out completely.
hi every body
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
I found on the other side of the butterfly flap - the side facing the engine - there was a large amount of oil residue on the flap itself and around the opening. This is the side you can't see or access if you are just cleaning it from the front of the car. I didn't think to take pictures until after I had finished the job.
Anyway, I used some TB cleaner to get all the gunk off to where all you could see was shiny silver. Then I went to work on the internals. I figured since I was possibly going to have to buy a new TB anyway, it wouldn't really matter if I screwed this one up. I removed the 6 or so metal clips that held the black plastic piece on the side and then pulled the plastic piece straight out. The attached picture below is what it looks like with this plastic piece detached.
I used electrical contact cleaner to clean the carbon tracks and little metal "brushes" and then did a few light sprays on the gears and copper connectors and put the cover and clips back on. Note that if you do this, the plastic/nylon gear may fall off but you can just gently put it back in place. I would advise not actually touching the metal "brushes." I cleaned the carbon tracks with a shop towel and was able to get a good amount of black residue off.
I then re-installed the TB and had the smoothest start and idle I've ever felt while owning this car. It has been 2 weeks now and everything seems perfect, so I think I finally fixed the problem and avoided having to buy a new TB. Cruise control is now much smoother than it had been and even on cold mornings the starts and idles are flawless now.
So in summary, I would suggest saving yourself $600 by attempting to thoroughly clean your TB before buying a new one.
After reading the entirety of this thread, I decided the TB (throttle body/actuator) had to be the source of my problems. I believe a new TB is about $600. Instead of immediately buying a new one and replacing it, I decided to see what I could do with my current one, so I took the TB out completely.
hi every body
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
I found on the other side of the butterfly flap - the side facing the engine - there was a large amount of oil residue on the flap itself and around the opening. This is the side you can't see or access if you are just cleaning it from the front of the car. I didn't think to take pictures until after I had finished the job.
Anyway, I used some TB cleaner to get all the gunk off to where all you could see was shiny silver. Then I went to work on the internals. I figured since I was possibly going to have to buy a new TB anyway, it wouldn't really matter if I screwed this one up. I removed the 6 or so metal clips that held the black plastic piece on the side and then pulled the plastic piece straight out. The attached picture below is what it looks like with this plastic piece detached.
I used electrical contact cleaner to clean the carbon tracks and little metal "brushes" and then did a few light sprays on the gears and copper connectors and put the cover and clips back on. Note that if you do this, the plastic/nylon gear may fall off but you can just gently put it back in place. I would advise not actually touching the metal "brushes." I cleaned the carbon tracks with a shop towel and was able to get a good amount of black residue off.
I then re-installed the TB and had the smoothest start and idle I've ever felt while owning this car. It has been 2 weeks now and everything seems perfect, so I think I finally fixed the problem and avoided having to buy a new TB. Cruise control is now much smoother than it had been and even on cold mornings the starts and idles are flawless now.
So in summary, I would suggest saving yourself $600 by attempting to thoroughly clean your TB before buying a new one.
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 250
Likes: 0
From: Charleston, SC
2005 C230K
hi every body
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
Newbie
Joined: Jul 2010
Posts: 1
Likes: 0
2005 C230 Kompressor
hi every body
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
after more than 2 months and did:
1: cleaned TB in\outside.
2:replace 2 hoses under air filter
3:clean MAF.
4:replace all mounten .
there is no error codes.
i still have rough vibration when in red light if AC on +gear on D.
please help guys
plzzzzzzzzzzzzzzzzzzzzzzzz
