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 06-24-2019, 04:24 PM
Registered User
 
Join Date: May 2002
Location: Washington, D.C.
Posts: 425
Question about adjusting mixture - 560SEL

Preamble: So my mechanic has determined that my engine is running lean, because of bad plenum seals. He has sprayed starter fluid into the back of the intake manifold and the car started acting up. That should not happen if there is not a leak, I take him by his word.

The problem: So to get the car to drive again somewhat reasonably so I can take it to my shop to replace the plenum seals, he enriched the mixture. Problem is when I tried to start the car the next day, it would not. My attempts to fix the mixture, as per his instructions, have failed miserably, and I am afraid I now have the CIS mixture plate adjustment screw way out of whack.

So I go this idea: Instead of me running back and forth between the front of the car and the ignition switch, doing 1/8th turns on the screw, I could have my wife run the starter while I turn the adjustment screw until we get her fired up.

Does this seem like a reasonable plan?

Any comments and suggestions welcome...
__________________
Henry Bofinger
1989 560 SEL (black/black)
2001 Audi TT Roadster (silver/grey)

Last edited by hbofinger; 06-24-2019 at 05:21 PM.
Reply With Quote
  #2  
Old 06-25-2019, 04:19 AM
Registered User
 
Join Date: May 2002
Location: Washington, D.C.
Posts: 425
Hello, anyone?

Is this a good way to go?
__________________
Henry Bofinger
1989 560 SEL (black/black)
2001 Audi TT Roadster (silver/grey)
Reply With Quote
  #3  
Old 06-25-2019, 08:56 AM
rwd4evr's Avatar
Master hull craftsman
 
Join Date: Apr 2012
Location: delaware
Posts: 589
Press the plate slightly while trying to start it. If it's leaking air it will be running lean and want more fuel.

Sent from my SM-J737A using Tapatalk
__________________
WARNING!!! VINTAGE MERCEDES MAY MULTIPLY UNCONTROLABLY!!! I have tons of Sl/Slc parts w108 w111 w126 and more. E-mail me with needs
BirchsgarageMB@gmail.com
Reply With Quote
  #4  
Old 06-25-2019, 05:56 PM
Registered User
 
Join Date: Feb 2011
Location: Modesto CA
Posts: 2,748
Quote:
Originally Posted by hbofinger View Post
Preamble: So my mechanic has determined that my engine is running lean, because of bad plenum seals. He has sprayed starter fluid into the back of the intake manifold and the car started acting up. That should not happen if there is not a leak, I take him by his word.

The problem: So to get the car to drive again somewhat reasonably so I can take it to my shop to replace the plenum seals, he enriched the mixture. Problem is when I tried to start the car the next day, it would not. My attempts to fix the mixture, as per his instructions, have failed miserably, and I am afraid I now have the CIS mixture plate adjustment screw way out of whack.

So I go this idea: Instead of me running back and forth between the front of the car and the ignition switch, doing 1/8th turns on the screw, I could have my wife run the starter while I turn the adjustment screw until we get her fired up.

Does this seem like a reasonable plan?

Any comments and suggestions welcome...

hb:

1) Within the range of compensation of the mixture controller, it will adjust the mixture to stochiometric irrespective of the source of air.
A significant leak of unmeasured air will cause starting difficulties with a warm engine. With a cold engine, all the compensations will push the mixture in the rich direction, and if the ambient temperature is below ~ 55F, the cold start injector will further enrich the mixture for a couple of seconds.

2) If the sensor plate-to-metering plunger relationship was indeed adjusted in the rich direction, there should not be a cold starting problem. If the adjustment was made in the lean direction, there may indeed be a problem. As suggested by rwd, slightly depressing the sensor plate while cranking will provide extra fuel.

Did the person who "enriched" the mixture tell you the direction in which the screw was moved, and the amount? And have you recorded your moves?
Reply With Quote
  #5  
Old 06-25-2019, 09:55 PM
lsmalley's Avatar
Registered User
 
Join Date: Oct 2006
Location: California
Posts: 1,958
Applies to 560 series
https://www.landiss.com/mixture.htm
__________________

1990 190E 2.6L
Reply With Quote
  #6  
Old 06-27-2019, 02:28 PM
Registered User
 
Join Date: May 2002
Location: Washington, D.C.
Posts: 425
Thank you for those replies...

I was aware of the riching of the fuel at start.

My mechanic is going to come by Monday evening and see if he can get her started. I have got her to the point that she runs one revolution after the starter is disengaged. So I am close...
__________________
Henry Bofinger
1989 560 SEL (black/black)
2001 Audi TT Roadster (silver/grey)
Reply With Quote
  #7  
Old 06-27-2019, 02:45 PM
Registered User
 
Join Date: Feb 2011
Location: Modesto CA
Posts: 2,748
Quote:
Originally Posted by hbofinger View Post
I was aware of the riching of the fuel at start.

My mechanic is going to come by Monday evening and see if he can get her started. I have got her to the point that she runs one revolution after the starter is disengaged. So I am close...

hb:

If you turn the key to the ignition position (not the cranking/starting position), do you hear the fuel pumps run for 1-2 seconds and then shut off? If you do not hear the pumps, they will run when the starter is cranking, the engine will fire briefly, and then shut off when the key is released from starting. In this scenario, the fault is with the fuel pump relay.
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 07:20 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, 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