Rough Idle

EddieS320 · 03-14-2010, 08:19 PM

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?

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barry S320V · 03-15-2010, 01:15 PM

which wires are you refering to, the plug wires or the wireing loom?

EddieS320 · 03-16-2010, 11:08 AM

The wires I replaced were the spark plug wires.

EddieS320 · 03-16-2010, 11:13 AM

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.

symbolic95 · 03-16-2010, 09:59 PM

Quote:

Originally Posted by EddieS320

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.

How is ETA wiring harness ?

EddieS320 · 03-17-2010, 06:43 PM

What is (where is) the ETA wiring harness?

benica · 03-18-2010, 05:46 AM

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!)

barry S320V · 03-18-2010, 12:58 PM

it is a good idea to check the thin plastic vacuum lines as they become very brittle over time.

symbolic95 · 03-18-2010, 11:13 PM

Quote:

Originally Posted by EddieS320

What is (where is) the ETA wiring harness?

Electronic throttle actuator-ETA , check also MAF wires and starter wiring harness

benica · 03-19-2010, 06:06 AM

Quote:

Originally Posted by barry S320V

it is a good idea to check the thin plastic vacuum lines as they become very brittle over time.

The plastic ones also crack due to heat over time...become brittle....I've replaced many.

geebee · 03-23-2010, 06:51 PM

Try:

http://baxnet.com/merc

and look for ETA Rebuild

Good luck!

benica · 03-24-2010, 01:42 AM

Quote:

Originally Posted by geebee

Try:

http://baxnet.com/merc

and look for ETA Rebuild

Good luck!

I spent 30 minutes looking/reading at the above site! Great deal of info! Anyone know how to contact Greg directly? E-mail address?

tomsantos · 11-26-2011, 03:57 PM

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.

barry S320V · 11-26-2011, 04:17 PM

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.

oldsinner111 · 12-11-2011, 11:53 AM

I get my alternators rebuilt for $85.

barry S320V · 12-11-2011, 01:51 PM

wow $85.00 do they install it for that price too?? lol.

When you spend the big money they give you free lattes while you watch their big screen tv and drive you home.

03-15-2010, 01:15 PM	#2
barry S320V Member Garage is empty, add now Join Date: Jun 2003 Location: vancouver bc Posts: 90 Drives: 1995 S320V	wires which wires are you refering to, the plug wires or the wireing loom? __________________ 1995 S320V Smoke silver palamino leather 6 cd changer power everything

03-17-2010, 06:43 PM	#6
EddieS320 Newbie Garage is empty, add now Join Date: Mar 2010 Posts: 4 Drives: S320	Rough Idle What is (where is) the ETA wiring harness?

03-18-2010, 05:46 AM	#7
benica Junior Member Garage is empty, add now Join Date: Feb 2010 Location: Honolulu!!! The best place in the world to be! Hawaii! Posts: 74 Drives: '92 500 SEL, '68 VW Fiberglass Dune Buggy, '05 CL55 AMG Coupe.	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!) Last edited by benica; 03-18-2010 at 05:48 AM.

03-18-2010, 12:58 PM	#8
barry S320V Member Garage is empty, add now Join Date: Jun 2003 Location: vancouver bc Posts: 90 Drives: 1995 S320V	plastic it is a good idea to check the thin plastic vacuum lines as they become very brittle over time. __________________ 1995 S320V Smoke silver palamino leather 6 cd changer power everything

03-23-2010, 06:51 PM	#11
geebee Newbie Garage is empty, add now Join Date: Mar 2010 Posts: 1 Drives: 98 S500, 99 S500	Try: http://baxnet.com/merc and look for ETA Rebuild Good luck! __________________ === Remember - "There's nothing like the ride of a well tuned 140 - NOTHING" - Baxnet

03-16-2010, 11:08 AM	#3
EddieS320 Newbie Garage is empty, add now Join Date: Mar 2010 Posts: 4 Drives: S320	The wires I replaced were the spark plug wires.

03-16-2010, 11:13 AM	#4
EddieS320 Newbie Garage is empty, add now Join Date: Mar 2010 Posts: 4 Drives: 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.

11-26-2011, 03:57 PM	#13
tomsantos Junior Member Garage is empty, add now Join Date: Aug 2010 Location: San Jose, CA Posts: 15 Drives: 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.

11-26-2011, 04:17 PM	#14
barry S320V Member Garage is empty, add now Join Date: Jun 2003 Location: vancouver bc Posts: 90 Drives: 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. __________________ 1995 S320V Smoke silver palamino leather 6 cd changer power everything

12-11-2011, 11:53 AM	#15
oldsinner111 Senior Member 1999 Mercedes-Benz S-Class Join Date: Jun 2010 Location: tennessee Posts: 335 Drives: s320 and 300sd	I get my alternators rebuilt for $85. __________________ 1999 S320 plus nitrous 355 hp. 1983 300 SD not stock

12-11-2011, 01:51 PM	#16
barry S320V Member Garage is empty, add now Join Date: Jun 2003 Location: vancouver bc Posts: 90 Drives: 1995 S320V	$85. wow $85.00 do they install it for that price too?? lol. When you spend the big money they give you free lattes while you watch their big screen tv and drive you home. __________________ 1995 S320V Smoke silver palamino leather 6 cd changer power everything

12-11-2011, 01:51 PM
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