Dip in Idle
Thread Starter
Member
Joined: Feb 2003
Posts: 85
Likes: 0
From: NW Arkansas
05 C230 Sports Sedan, Previously owned an 02 C230 Sports Coupe
Dip in Idle
I've searched the forum, but I can't really find an answer to my problem.
My 2005 C230 Sports Sedan is experiencing a weird problem. When the car is idling - say at a stop sign - the car usually hovers around 800 RPM. It has always done so. Lately about every 10 seconds or so, the RPM will dip say to about 600 and then quickly come back up to the 800RPM level. This is when the car is in drive.
It doesn't appear to have the problem as bad when it is in park. In park, the car idles around 1K and sometimes dips and comes back up.
I originally thought that this was only happening when the air conditioning was on, but it does happen when the air is off too. I took the car to the dealer. They replaced the plugs, wires, a couple of other items, and then we began to address the oil leaks that were starting around sever engine seals. 2,200 dollars later, I have the car back, but it still does the same thing. It doesn't throw any codes, and I'm wondering if this is normal.
I just don't remember the car ever really dipping in RPM like that at stop signs?
Any thoughts?
My 2005 C230 Sports Sedan is experiencing a weird problem. When the car is idling - say at a stop sign - the car usually hovers around 800 RPM. It has always done so. Lately about every 10 seconds or so, the RPM will dip say to about 600 and then quickly come back up to the 800RPM level. This is when the car is in drive.
It doesn't appear to have the problem as bad when it is in park. In park, the car idles around 1K and sometimes dips and comes back up.
I originally thought that this was only happening when the air conditioning was on, but it does happen when the air is off too. I took the car to the dealer. They replaced the plugs, wires, a couple of other items, and then we began to address the oil leaks that were starting around sever engine seals. 2,200 dollars later, I have the car back, but it still does the same thing. It doesn't throw any codes, and I'm wondering if this is normal.
I just don't remember the car ever really dipping in RPM like that at stop signs?
Any thoughts?
Super Member
Joined: Dec 2010
Posts: 712
Likes: 2
From: chicago
2005 c230 kompressor 2003 s500 94 wrangler
u could be getting a check engine..if something happends it could take a while to show
how old is ur battery? air filters?....fuel filters?
put techron in only fuel cleaner approved by mercedes
oh ya about the car always being at 800 rpm at a stoplight thats WAAYYY TO HIGH
i had my car since new and its supposed to be at 500 rpm in drive...then 550 rpm in park
how old is ur battery? air filters?....fuel filters?
put techron in only fuel cleaner approved by mercedes
oh ya about the car always being at 800 rpm at a stoplight thats WAAYYY TO HIGH
i had my car since new and its supposed to be at 500 rpm in drive...then 550 rpm in park
Last edited by sammydragon3; May 12, 2012 at 10:22 AM.
Junior Member
Joined: Sep 2011
Posts: 63
Likes: 0
From: Ontario, Canada
2004 Mercedes-Benz C Class
Honestly, mine has fluctuate like that when in drive from 600 to 500, and it's 70,000KM later it still does it and hasn't hinder performance and hasn't risen any engine problems. So I say don't worry about it and just enjoy your car.
... 800 does seem a tad bit high but it depends on the engine 2.6L V6 idles around 600to500 at stoplights, my cousins c230 4CYL idles 800 so I don't know what to say in terms of idle RPM seems to be engine dependant. In terms of fluctuation I say it's normal, don't worry about it or you'll keep tossing money into the pit.
I am considering changing my spark plugs if you haven't you may want to consider depending on how old the spark plugs are. Mine is the original has about 180000K on the original spark plugs so I say sometime it would be good to change it out. Changing old nasty spark plugs for new ones usually in a good bit of cases result in smoother idle.
... 800 does seem a tad bit high but it depends on the engine 2.6L V6 idles around 600to500 at stoplights, my cousins c230 4CYL idles 800 so I don't know what to say in terms of idle RPM seems to be engine dependant. In terms of fluctuation I say it's normal, don't worry about it or you'll keep tossing money into the pit.
I am considering changing my spark plugs if you haven't you may want to consider depending on how old the spark plugs are. Mine is the original has about 180000K on the original spark plugs so I say sometime it would be good to change it out. Changing old nasty spark plugs for new ones usually in a good bit of cases result in smoother idle.
Last edited by xijonix; May 13, 2012 at 01:50 AM.
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Joined: Jul 2008
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2019 G70 6MT & 2022 Ford Maverick XL
Wtf Sammy.. "you could be getting a check engine"? I think he would know if the CEL was coming on. He says it does not have codes.
Have you cleaned the MAF? Replaced the O2 sensors? How many miles do you have? Mine will dip now and then and recover, but constantly is definitely not right.
Have you cleaned the MAF? Replaced the O2 sensors? How many miles do you have? Mine will dip now and then and recover, but constantly is definitely not right.
Super Member
Joined: Dec 2010
Posts: 712
Likes: 2
From: chicago
2005 c230 kompressor 2003 s500 94 wrangler
Wtf Sammy.. "you could be getting a check engine"? I think he would know if the CEL was coming on. He says it does not have codes.
Have you cleaned the MAF? Replaced the O2 sensors? How many miles do you have? Mine will dip now and then and recover, but constantly is definitely not right.
Have you cleaned the MAF? Replaced the O2 sensors? How many miles do you have? Mine will dip now and then and recover, but constantly is definitely not right.
and i never got a check engine for like a week after
MBWorld Fanatic!
Joined: Jun 2011
Posts: 1,494
Likes: 131
From: Cape town
not a merc
usually a mixture problem, engine is too lean. check for airleaks airleaks airleaks. when they are right it should not hunt at all.
Once you have fixed any air leaks service the throttle body have all adaptations reset, and you good to go.
Once you have fixed any air leaks service the throttle body have all adaptations reset, and you good to go.
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From: So Cal.
2019 GT3 RS, 2017 M3 30 Jahre
Honestly, mine has fluctuate like that when in drive from 600 to 500, and it's 70,000KM later it still does it and hasn't hinder performance and hasn't risen any engine problems. So I say don't worry about it and just enjoy your car.
... 800 does seem a tad bit high but it depends on the engine 2.6L V6 idles around 600to500 at stoplights, my cousins c230 4CYL idles 800 so I don't know what to say in terms of idle RPM seems to be engine dependant. In terms of fluctuation I say it's normal, don't worry about it or you'll keep tossing money into the pit.
I am considering changing my spark plugs if you haven't you may want to consider depending on how old the spark plugs are. Mine is the original has about 180000K on the original spark plugs so I say sometime it would be good to change it out. Changing old nasty spark plugs for new ones usually in a good bit of cases result in smoother idle.
... 800 does seem a tad bit high but it depends on the engine 2.6L V6 idles around 600to500 at stoplights, my cousins c230 4CYL idles 800 so I don't know what to say in terms of idle RPM seems to be engine dependant. In terms of fluctuation I say it's normal, don't worry about it or you'll keep tossing money into the pit.
I am considering changing my spark plugs if you haven't you may want to consider depending on how old the spark plugs are. Mine is the original has about 180000K on the original spark plugs so I say sometime it would be good to change it out. Changing old nasty spark plugs for new ones usually in a good bit of cases result in smoother idle.
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Super Member
Joined: Mar 2007
Posts: 812
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From: centennial, CO
2003 c240
Mine does this often too and I replaced the plugs, wires, cleaned maf, and run techron through regularly. It never goes away and I can't find a solution. I just learned to live with it.
Thread Starter
Member
Joined: Feb 2003
Posts: 85
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From: NW Arkansas
05 C230 Sports Sedan, Previously owned an 02 C230 Sports Coupe
I got tied up with work the last couple of days, and I haven't really been leaving the office often.
I haven't tried the techron yet, but I do still have the problem. This morning when I went to leave my garage, the car noticeably shook roughly while the car was in the driveway. I can live with a bit of a fluctuation, but the car has about 106,000 miles on it. They did change the plugs and wires, as well as several oil gaskets that needed to be replaced.
I guess it's frustrating because the car has always ran so smooth. Anyone would have noticed this behavior. I may take it back to the dealer tomorrow and have them take another look. I could wait to see if something breaks down, but prevention is more my style. Noise is friction. Friction is wear, and wear is money. This isn't a noise, but I'm sure if I let it go longer it will cost even more money to fix.
I haven't tried the techron yet, but I do still have the problem. This morning when I went to leave my garage, the car noticeably shook roughly while the car was in the driveway. I can live with a bit of a fluctuation, but the car has about 106,000 miles on it. They did change the plugs and wires, as well as several oil gaskets that needed to be replaced.
I guess it's frustrating because the car has always ran so smooth. Anyone would have noticed this behavior. I may take it back to the dealer tomorrow and have them take another look. I could wait to see if something breaks down, but prevention is more my style. Noise is friction. Friction is wear, and wear is money. This isn't a noise, but I'm sure if I let it go longer it will cost even more money to fix.
Thread Starter
Member
Joined: Feb 2003
Posts: 85
Likes: 0
From: NW Arkansas
05 C230 Sports Sedan, Previously owned an 02 C230 Sports Coupe
OK, I have the car back. And, yes, I took it back to the shop to have it looked at again. The car wouldn't do it in the service bay. Very annoying. I think that I have found that it really is tied to the air conditioning system. It feels almost like the AC compressor is introducing a load intermittently. I know they replaced an air conditioning part a few months back - not the compressor. Is there a belt that could be slipping or a tension mechanism that could be set incorrectly?
Thread Starter
Member
Joined: Feb 2003
Posts: 85
Likes: 0
From: NW Arkansas
05 C230 Sports Sedan, Previously owned an 02 C230 Sports Coupe
Well, here we go.
It is apparently a butterfly valve within the Throttle Body assembly that is not closing properly. The new part - wait for it - with the hour labor is going to be $1,650.00.
It is apparently a butterfly valve within the Throttle Body assembly that is not closing properly. The new part - wait for it - with the hour labor is going to be $1,650.00.
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Joined: Jul 2008
Posts: 8,384
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2019 G70 6MT & 2022 Ford Maverick XL
The engine mounts really smooth the engine out. Doesn't mean the dip will go away, but it does smooth out.
Underwhirled, that is highway robbery. Yes the throttle body is expensive but that is ridiculous. You could easily DIY. Here is the part for $736:
http://www.rmeuropean.com/Part-Numbe..._94E6B777.aspx
Underwhirled, that is highway robbery. Yes the throttle body is expensive but that is ridiculous. You could easily DIY. Here is the part for $736:
http://www.rmeuropean.com/Part-Numbe..._94E6B777.aspx
