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 10-08-2001, 07:19 AM
Posts: n/a
Unhappy 450SEL m117 engine


I have a 1974 450SEL with electronic fuel injection. Car starts fine, runs at 2000 rpm, blip throttle revs drop but dont settle to steady idle. Engine revs up to 2500rpm then cuts, drops to 500rpm and catches and revs to 2500 rpm again. If I blip the throttle again the engine will rev to about 3000rpm and stay there. Have I lost a temperature sensor? Is the cold start valve stuck on? How do these things measure air flow? The Haynes manual is as much use as a chocolate fireguard. Any ideas of what to check first would be gratefully received. Any ideas of where I can get an engine manual with ignition info would be a bonus. Thanks .

Colin Whyte
Reply With Quote
Old 10-08-2001, 09:19 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
Check for a large vacuum leak, broken hoses, or a bind in the linkage.
Donnie Drummonds
Reply With Quote
Old 10-08-2001, 10:00 PM
RunningTooHot's Avatar
Registered User
Join Date: Aug 2000
Location: Here
Posts: 775
A: they don’t actually measure intake air volume – this setup uses a vacuum signal to indicate load on the engine. It is an approximately baseball sized unit with a fairly large diameter hose from the intake manifold running to it. If yours is a 4.5, it should have a blue color code on it (3.5s are yellow)

B: This could be a combination of factors, one of which sounds like the (timing advance) weights inside the distributor are sticking. This really seems unlikely due to the propensity of the distributor shaft seals to go bad – this is why/how the injector trigger points get fouled with oil. You may want to put a timing light on it to see how the advance curve looks – does it move smoothly with increasing RPMs, or does it jump around? Also look for consistent readings at the same RPMs

Good Luck!

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
Oil Additives Bill Wood Performance Paddock 6 08-24-2011 10:53 AM
noisy engine Hocky Tech Help 0 02-28-2004 08:39 PM
Any fanatics religiously change oil @ 2.5K intervals or less? -fad Tech Help 60 03-19-2002 11:22 AM
Fuel Trim? OBDII cycle and CHECK ENGINE ? ke6dcj Tech Help 1 08-06-2001 08:54 AM

All times are GMT -4. The time now is 07:36 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