Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 09-14-2017, 12:48 PM
lsmalley's Avatar
Registered User
 
Join Date: Oct 2006
Location: California
Posts: 1,979
Angry M103 rough idle...yet again.

The only thing I hate about the m103 is that it seems to always develop a rough idle. I have no vacuum leaks, 2 new fuel pumps and fuel filter, spark plugs done yesterday with Bosch H9DC non-resistor plugs, K&N filter is good, even if I have the air cleaner housing off at idle it's still rough. Less than 40k miles on O2 sensor.

__________________

1990 190E 2.6L
Reply With Quote
  #2  
Old 09-14-2017, 01:24 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 5,193
Cap and rotor? Crappy fuel? K-Jet needs adjustment? Exhaust leak? EZL? Weak ignition coil? The list goes on. The rough idle won't show up for no reason, there's ALWAYS a reason.
__________________
'11 Honda Accord EX - "The Daily" 70K
'83 500SL Euro - "The Money Pit" 116K
'91 350SD - "Diseasel Jr." 173K
'94 BMW 525i - "The Red Car" 180k
Reply With Quote
  #3  
Old 09-14-2017, 01:47 PM
lsmalley's Avatar
Registered User
 
Join Date: Oct 2006
Location: California
Posts: 1,979
Cap and rotor were checked with plugs last night, but I will be checking everything else that was mentioned. Fuel has always varied from different stations so I doubt they all decided to water down their fuel ��
__________________

1990 190E 2.6L
Reply With Quote
  #4  
Old 09-14-2017, 02:23 PM
dynalow's Avatar
Registered User
 
Join Date: Feb 2002
Posts: 1,599
91 300e slight idle problem
old thread same topic.
I only searched the first 2 pages for M103 rough idle. What year is your car again?
Reply With Quote
  #5  
Old 09-14-2017, 02:32 PM
lsmalley's Avatar
Registered User
 
Join Date: Oct 2006
Location: California
Posts: 1,979
Quote:
Originally Posted by dynalow View Post
91 300e slight idle problem
old thread same topic.
I only searched the first 2 pages for M103 rough idle. What year is your car again?
1990
__________________

1990 190E 2.6L
Reply With Quote
  #6  
Old 09-14-2017, 04:30 PM
Mike Murrell's Avatar
Registered User
 
Join Date: Feb 2000
Posts: 2,574
This may not sound very scientific, but did the vehicle ever have a smooth idle and if so, what's changed since then?
__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"
Reply With Quote
  #7  
Old 09-14-2017, 05:30 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Location: Texas Hill Country
Posts: 5,193
Adding to Mike's comment above - just how rough is "rough"? Shaking the car? Dropping the mirror off the windshield? Or just a bit of annoying vibration? How are your engine mounts?
__________________
'11 Honda Accord EX - "The Daily" 70K
'83 500SL Euro - "The Money Pit" 116K
'91 350SD - "Diseasel Jr." 173K
'94 BMW 525i - "The Red Car" 180k
Reply With Quote
  #8  
Old 09-14-2017, 08:44 PM
ps2cho's Avatar
Registered User
 
Join Date: Jun 2006
Location: Chandler, Arizona
Posts: 3,523
After spending a lot of time going through CIS-E, the first thing you need to do is look at the duty cycle and EHA amp's and report back with the findings.
Secondly probe the potentiometer and verify the voltage.
__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k
Reply With Quote
  #9  
Old 09-14-2017, 10:58 PM
w123fanman's Avatar
Registered User
 
Join Date: Jun 2011
Location: Georgia Tech, Atlanta, GA
Posts: 1,544
This is why I bought Matt's MS2 setup. CIS is finicky. Pretty reliable, but getting it running just right is a pain.
__________________
80 300SD 183K
83 300D manual 100K chassis
86 Yugo GV 48K
88 Yugo GVX 9K
90 300D 230K
90 Lexus LS400 189k
91 F150 4.6 4v 160K
93 190E 3.0 Sportline Limited Edition 230K
93 190E 2.6 Sportline Limited Edition 91K
96 MGM LS 242K- RIP
03 Sprinter Passenger 220K
06 MGM LS 105K-sold
Parts cars:
77 240D Auto-RIP
79 300SD- RIP
80 300SD
83 240D-RIP
85 240D-RIP
87 190D-RIP
91 190E 2.3- RIP
93 190E 2.6-RIP
Reply With Quote
  #10  
Old 09-16-2017, 03:02 AM
lsmalley's Avatar
Registered User
 
Join Date: Oct 2006
Location: California
Posts: 1,979
Performed all CIS-E tests according to fsm and everything checked out within spec. Ended up removing everything I did previously when changing iacv hoses. Pulled all fuel injectors and ended up changing out one that seemed suspect with the spray pattern. Cleaned/lubricated all links with atf, buttoned it all back up. Idle was at 2500 rpm! But super smooth. Not wanting to mess with anything adjustment wise I drove car to a desolate location and opened the hood to check throttle cable and micro switch, but were fine. I then went with my gut instinct which was to check the air meter attached to the throttle body. I tapped it with a long socket extension and rpm dropped down to about 700 and was smooth.. Driving now and all is well.

__________________

1990 190E 2.6L
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 05:05 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page