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

LinkBack Thread Tools Display Modes
Old 12-29-2001, 08:37 AM
Posts: n/a
Angry 126 Fast Idel Problem

I have 500 SEL 1984 with 97K miles on it, recently at start up it is taking a little longer to turn over (6-8 Seconds) additionally intermittently it will go from idling its normal 600 RPM to 1500-1600 RPM and will not kick down. It will continue to idel this way for some time. This is an intermittent problem does not occur every time.The engine is spotless all linkage is clean and working properly. Up until thNo major changes have been done to the engine to cause this to happen. Does anyone have any suggestions it would be greatly appreciated.
Reply With Quote
Old 12-29-2001, 03:41 PM
Registered User
Join Date: Jul 2000
Location: Toronto, CANADA
Posts: 1,193
Have you changed the Overvoltage proterction relay? It is among other things responsible for idle control. It is the little silver box to the left of your fuse box. It has a red top with a 10 amp fuse in it. Check the fuse first - dealer gave me a replacement for free, and if that doesn't work replace the relay, it simply pulls out and plugs in. Cost me about $120 Canadian and it is the best repair/replacement I have made.
Jason Priest
1999 E430
1995 E420 - retired
1986 420SEL - retired
Reply With Quote
Old 12-29-2001, 10:12 PM
Registered User
Join Date: Apr 2000
Location: eastern NC
Posts: 149
I too had the same problem. I changed the OVP and that didn't do it. I cleaned the Idle valve and that did't do it either although it is a good idea to do a through cleaning of this valve. I even re-soldered the joints in the idle control module. That worked for a short time. Finally I bit the bullet and ordered a new module. That cured the problem. My guess is that you too will need a new idle speed control module. E-mail me if you need a good source.
Reply With Quote
Old 12-30-2001, 12:37 AM
ymsin's Avatar
Driver, Mercedes-Benz
Join Date: Feb 2001
Location: Malaysia
Posts: 1,645
2 factors to consider:

1. Idle Valve Control that may need replacing or dirt (if intermitten); or
2. Accelerator cable link is jammed and needs to be lubed or perhaps looked into. The 126, unlike the 124, does not run on cables and has links: K-jet which can be lubed.

I don't suspect an OVP problem here.
... Kerry

126 tailed by a 203, 129 leading the pack.
Reply With Quote
Old 12-30-2001, 10:16 AM
Mike Murrell's Avatar
Registered User
Join Date: Feb 2000
Posts: 2,359
This thread may not line up exactly with your situation, but it won't heard to check it out.

Idle too fast or won't start
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
Reply With Quote
Old 12-30-2001, 10:26 AM
Registered User
Join Date: Dec 2001
Location: Wilkes-Barre, PA
Posts: 106
I had the same problem. It was fixed by replacing the idle speed control module.
02 E320 4Matic
01 E320 4Matic Wagon
01 E320 Wagon (wrecked PM if you need parts)
99 SLK 230
Reply With Quote
Old 12-31-2001, 10:34 AM
Registered User
Join Date: Apr 2001
Location: Washington, DC
Posts: 223
I also had the smae problem cured by the replacement of the idle control module in an '88 420SEL -- expensive part: $300+.
Reply With Quote
Old 12-31-2001, 11:41 AM
420benz's Avatar
Registered User
Join Date: Jul 2001
Posts: 961
Where is the IDLE SPEED CONTROL MODULE on the 89 420?
Reply With Quote
Old 12-31-2001, 01:47 PM
Registered User
Join Date: Apr 2000
Location: eastern NC
Posts: 149
I am not sure about the 420 series but I bet it is in the same location as my 380. Check on the firewall about half-way of the engine. It is a black box about 4 by 11/2 inches and is held in place by a 10 mm screw. Loosen the nut( careful not to drop it) and pull the module and its harness out. It pulls away from the harness. The solder joints in these things are brittle and constantly fail. You can try to re-solder them or just buy a new one. I paid $250. It was worth it.
Reply With Quote
Old 01-02-2002, 01:56 PM
dpetryk's Avatar
Electrons can do anything
Join Date: Sep 2001
Location: Houston, Texas
Posts: 1,071
On the 420 series it is located on the inside of the passenger compartment on the firewall passenger side.
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k
Reply With Quote


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
W140 Blower Regulator Problem bdonkersgoed Tech Help 12 06-08-2004 03:25 PM
280 SE 1984 mixture problem w126/280SE Tech Help 3 05-30-2004 10:42 AM
OVP issues and idle problem sbourg Tech Help 6 03-02-2003 09:49 AM
126 chassis sliding roof problem autozen Tech Help 3 04-03-2002 01:07 PM
82 300CD throttle problem? Billybob Diesel Discussion 1 03-24-2002 12:05 AM

All times are GMT -4. The time now is 06:18 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, 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