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 ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 02-24-2001, 01:17 PM
John Bobo
Guest
 
Posts: n/a
1994 E320 wagon, w104.992, 138,000 miles
At operating temperature (90 deg. c), in any forward gear or reverse, idle rpm's fluctuate from around 600 to 1100 rpm. Shift the selector lever to neutral or park and the idle fluctuation ceases; however, a slight miss is still evident. Check engine light has not illuminated. I inspected the wiring harness for cracked insulation none evident at coils or along fuel rail. Spark plugs replaced approximately 10,000 miles ago; plugs removed and inspected, no signs of fouling. Please offer suggestions on troubleshooting. ISC acutator? HFM-SFI control module? Any prior post in tech archives on this subject?
Reply With Quote
  #2  
Old 02-24-2001, 01:58 PM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
If you look at the article in DIY about driveability, it shows a method for pulling codes on the sixteen pin connector. You should check for codes on the EA/CC/ISC module and the HFM module. Codes set here only turn on the light if they activate the DM (diagnostic module). Check it also.

If you have no codes on any of the modules I would replace all three plug connectors beneath the coils. These often give misfires after plug replacement.

BTW the DM is on pin #3, the HFM is on pin #8, and the ISC is on pin #14.
__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote
  #3  
Old 02-24-2001, 07:53 PM
John Bobo
Guest
 
Posts: n/a
I checked the DM pin, HFM pin and ISC pin. ISC indicated three codes: 2, 5, and 11. No other codes were present. While performing this check, I double checked the vaccuum supply hoses. I discovered the vaccuum line on top of the intake manifold not connected. ??? I reconnected and the erratic idle ceased. Do the codes indicated relate to a vaccuum problem? Is there a printed code chart avaiable from MBUSA other than microfiche?

By the way, great article. Thank you for the suggestion.
Reply With Quote
  #4  
Old 02-24-2001, 09:06 PM
Moderator
 
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
MB publishes a code book that is half an inch thick and applies to models up to 1994. After that some models need a complete book just for themselves.

The codes you have suggest to me that you probably have a bad throttle assy. The first, #2 is for a bad ECU, #5 is for a stop light switch, and #11 is fuel safety shut-off closed throttle position error. The bad ECU code happens when too many things are implausible, usually not the control unit.

Erase the codes and see if they come back. If you have no further symptoms don't worry too much about accumulating codes over time.
__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Rough cold idle on 1991 420SEL BENZ-LGB Tech Help 15 06-20-2012 05:18 PM
ICV-what's it for? and can high idle hurt trans? gmercoleza Tech Help 10 11-18-2004 11:16 PM
380 Idle Control Valve Test ctaylor738 Tech Help 5 01-23-2004 02:33 PM
fast idle horror 84euro500 Tech Help 1 05-04-2003 10:21 PM
rough idle in drive 190E billwach Tech Help 11 12-16-2002 04:54 PM



All times are GMT -4. The time now is 10:38 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page