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 05-21-2001, 12:59 AM
Posts: n/a
I've been working on an 84 380 SL off and on for about the last month. The customer complained about a running problem. After testing, I came to the conclusion that it was running lean. The Oxygen sensor tested bad. I replaced it with a borg warner sensor. It is now switching properly. The fuel pressure is @82 psi, the volume is 3\4 of a quart in 15 seconds. Pressure at the warm-up regulator when the car is hot is 55psi. The ignition system checks ok. Off Idle to @ quarter throttle acceleration is ok, anything after that the car runs progressively leaner. I've watched oxygen sensor voltage whiile driving down the road it shows almost 0 voltage at wide open throttle. The ECM had had water damage from the evaporator leaking on it. I replaced it. It cured part of the problem but not all. My question now is concerning possibly a bad controller or frequency valve. Before I changed the controller, the duty cycle at the frequency valve was 24%. The controller would not change it. I manually richened and leaned out the car, but the controller would not react. The oxygen sensor read fine. After I found the corroded controller, I was sure I had found my problem. After replacing it, the car still ran lean. I checked my duty-cycle again, it was still at 24%. The controller had good grounds, power, o2 readings, tps signals,and connections. If I manually richened the fuel mixture on the car, either with the mixture screw or b-12, the duty cycle would decrease to a low of 9%. If I manually leaned the car out by vaccuum leaks or with the mixture screw I would get a maximum duty cycle of 38%. At wide open throttle when the duty cycle was supposed to be at a madatory 60%, it would go to 28% consistantly. I hooked into the frequency valve circuit via mercedes shop manual for the duty cycle check. I've yet to see the 50% that all of my information says I should have. People have told me to adjust by using the air\mixture screw, the car dies from the vast amount of adjustment before it hits 40%. Is it possible that a bad frequency valve could be the problem? The only test I've seen says if it buzz's it's good. It buzz's, but I wondered if a short in the windings could cause the problem now or if I have a bad controller. The consistant 24% duty cycle of both controllers is throwing me off. I would greatly appreciate any advice or information. May God bless your days and give you the skills to complete your daily jobs.

Thankyou, Outkast
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
mercedes 450sl fuel injection Michael Alex Vintage Mercedes 6 07-06-2009 01:47 PM
16v Fuel Injection Problem crbnfbr Tech Help 3 12-05-2003 04:24 PM
no fuel in injection lines tschepplmasta Tech Help 22 01-29-2003 08:47 PM
Mercedes 300D Fuel Injection Pump for only $75.00 Steve 300D Diesel Discussion 0 12-22-2002 07:06 PM
116 Fuel Injection Parts for Sale: 4.5 V-8 ejbrush Mercedes Used Parts For Sale & Wanted 0 11-10-2002 06:28 PM

All times are GMT -4. The time now is 10:50 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