Rough Idle
Thread Starter
Newbie
Joined: Mar 2010
Posts: 4
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S320
Rough Idle
1995 S320 166K recently began to idle rough at idle especially at traffic light. Idles smooth then suddenly drops as if to stall then smooths out again. Changed coils and wires will change plugs next, accelerates fine and mileage seems normal. Thinking fuel pump/filter???
any ideas?
any ideas?
Thread Starter
Newbie
Joined: Mar 2010
Posts: 4
Likes: 0
S320
Update: yesterday I cleaned the MAF sensor and the air temperature sensor with CRC. Idle is much better but still not perfect, but I think I read a thread here where it needs a little time to reset itself so I will give it a day or so.
Junior Member
Joined: Jun 2007
Posts: 15
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From: Orlando,Fl/Coral Springs,Fl
1994 S320 / 1984 300sd
Member
Joined: Feb 2010
Posts: 78
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From: Between Honolulu and Offutt.
1998 and 2002 SL 500, 2014 E550 Convertible
This is not going to help you at all....but, here's my .02 worth...rough idle can be caused by MANY things! Eliminate the obvious first....get a can or two of carb spray, engine on...and spray some cleaner around the hoses....idle goes up...you found one leak for sure.....vacuum line....your car has some age on it and the vacuum lines rot out....and MB's have miles of hoses! Could be something simple as a disconnected line which will cause rough idle. The other(s), electrical...you need an ORD 1/11 scanner for that....cheap to buy and it'll always come in handy and used on any car.
Could be fouled spark plugs.
Guessing and replacing parts gets expensive! The scanner is worth the money. (But hey, you're a rich guy...you won that multi million dollar lottery! Can't take it with you! I'm just joshing!)
Could be fouled spark plugs.
Guessing and replacing parts gets expensive! The scanner is worth the money. (But hey, you're a rich guy...you won that multi million dollar lottery! Can't take it with you! I'm just joshing!)
Last edited by benica; Mar 18, 2010 at 05:48 AM.
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Junior Member
Joined: Jun 2007
Posts: 15
Likes: 0
From: Orlando,Fl/Coral Springs,Fl
1994 S320 / 1984 300sd
Member
Joined: Feb 2010
Posts: 78
Likes: 0
From: Between Honolulu and Offutt.
1998 and 2002 SL 500, 2014 E550 Convertible
Junior Member
Joined: Mar 2010
Posts: 31
Likes: 1
98 S500, 2008 CLK550, 2010 S63 (sold), 2012 S550 (sold), 2012 E63
Member
Joined: Feb 2010
Posts: 78
Likes: 0
From: Between Honolulu and Offutt.
1998 and 2002 SL 500, 2014 E550 Convertible
Junior Member
Joined: Aug 2010
Posts: 24
Likes: 1
From: San Jose, CA
1997 MBZ S420
rough idle
Had the same problem mith my S420. MB Mechanic replaced vacuum hoses and 2 coils (which I suspect may not be the cause, but I relented). Cost is more than 700 bucks. Will pick the car up 2 days from now. Will post the outcome.
Member
Joined: Jun 2003
Posts: 90
Likes: 0
From: vancouver bc
1995 S320V
i have replace all coils, wireing loom, plug wires, and plugs. Big bux.
Things were fine for a while.
then last week wife takes car to airport, drops off sister. on restart car will only do 5 mph, engine light on.
mercedes mobile service replaced battery, big bix. then said the alternator is toast. to dealer, new alternator $1300. bux, car runs fine now.
Still love the car.
Things were fine for a while.
then last week wife takes car to airport, drops off sister. on restart car will only do 5 mph, engine light on.
mercedes mobile service replaced battery, big bix. then said the alternator is toast. to dealer, new alternator $1300. bux, car runs fine now.
Still love the car.
Newbie
Joined: Feb 2013
Posts: 10
Likes: 0
95 S320, 1960 190SL (waiting)
Must be nice. Mine cost me $210 AND the guy used VW parts to do it because he couldn't get MB parts.
That was ~2.5 years ago, so I'll still say it was worth it.
As a note: the guy that did my alternator said the VW bits were the same as the MB bits except for where the terminals are located.
HTH
M
That was ~2.5 years ago, so I'll still say it was worth it.
As a note: the guy that did my alternator said the VW bits were the same as the MB bits except for where the terminals are located.
HTH
M
