Parts Catalog Accessories Catalog Tech Info Tech Forums
  Search our site:    
 Cart  | Project List | Order Status | Help    

Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 11-29-2000, 11:28 AM
Registered User
Join Date: Nov 2000
Location: Tribune, Kansas. I farm for a living. I fly R/C airplanes for fun.
Posts: 53

I have a 1986 300E that is my first Benz, and I have owned it for a little over a month now. My idle speed seems to run a constant 1300 rpm with the engine either cold or hot. Is there any mechanical adjustment of the idle speed? Or any other kind of adjustment of the idle speed? Thanks.
Ron Miller

1986 300E
Reply With Quote
Old 11-29-2000, 11:50 AM
Posts: n/a
I'm not a tech and don't even want to take a stab at it.

However, since we're on the topic of idle I'd like to add an additional question here regarding idle on my 93 190 2.6:

At certain times, upon startup only, my idle will race up to 1300 or even 2200rpm and refuse to settle back until I start driving. This *only* happens when the car is warm and has been:
1) at elevated highway speeds for long period of time then shut down and re-started after a short duration (ie: fueling), or
2) if I'm re-starting (warm) after failing to fire it on the first attempt (read: let go of key too early and it died).

It's also stumbling on starter-power a little more before cleanly firing on warm starts, if that matters...

Keep in mind that this occurs infrequently after highway trips and occurs far more under scenario #2 above. Goosing the throttle rarely if ever helps re-set the idle. Only after shifting into gear and driving 1/4 mile or so will it re-adjust. I have no idea what may be causing this, besides possibly the O2 sensor or *shudder* the idle speed computer (doesn't that cost like $1700?!). My 90k service is coming up but I'd appreciate some help from those interested/knowledgeable about idle issues. Oh yeah - and it IS becoming more frequent. Ideas?

Reply With Quote
Old 11-29-2000, 07:26 PM
Registered User
Join Date: Nov 2000
Location: Tribune, Kansas. I farm for a living. I fly R/C airplanes for fun.
Posts: 53
I did some reading, and somewhere it said in park or
neutral trans position, there is a ground circuit that has to be there for
proper engine idle operation. I find my car will start in any gear!! Where is
the switch for the park/neutral position? Also, I find a little vacuum line
broken that comes from the pcv hose on top of the engine ( this black rubber
hose has a little manifold to adapt to the little hose size and goes from
the valve cover to the air cleaner cover) and runs down to around the "carb"
area. I would suppose this may have something to do with idle speed too?
Also, I checked the over voltage relay and it appears to be ok, and the fuse
is ok. I pulled the conn block of of the cis unit and checked the voltage
there according to my manual. Voltages there appear normal so far. Is all
this a big problem or can I dig in and do it myself?

Ron Miller

1986 300E
Reply With Quote
Old 11-29-2000, 09:29 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
Any vacuum leaks can cause a high idle. I would repair the vacuum leaks, then check to see where the idle is.

As for the Makakio, it would be easy to check this if the problem was happening. You will have to find a tech to look at it at the time of the failure.
Donnie Drummonds
Reply With Quote
Old 11-30-2000, 03:47 PM
Posts: n/a
Thanks Donnie - having it checked when-occurring is always the difficult part, no?
Reply With Quote
Old 11-30-2000, 05:01 PM
Ashman's Avatar
Service Advisor
Join Date: Sep 2000
Location: Sherman Oaks, CA
Posts: 4,748

I had a similar problem with my jeep. i would start it and it would go up to high revs and wouldn't come down at all sometimes.

I had to have something called the idle speed sensor or something like that replaced. or The Idle Control valve not sure what it was,but since i had that part replaced the car never did it again.

If you can start your car when its in gear, then most likely the the Neutral Safety switch has a problem.

Some cars may not have this feature, but i would assume most cars do.

P.S. i'm not a tech, but just thought this would assist because of the similarity of the problem even though in my case it applied to a jeep and not a benz.

'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.
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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
'82 300SD Idle Speed pawoSD Diesel Discussion 6 11-23-2010 07:50 AM
idle speed adjustment? odie Diesel Discussion 2 01-18-2005 04:20 PM
Idle speed control regulator lin Tech Help 2 03-02-2002 12:29 AM
Duty cycle for 300E Idle Speed Control ChinaClipper Tech Help 4 11-10-2001 03:18 PM
'83MB 300SD Idle Speed Wm. Lewallen Tech Help 2 04-24-2000 08:52 PM

All times are GMT -4. The time now is 02:46 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, 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