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 07-13-2013, 06:25 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,038
M104 Running Rough. Thoughts?

Hey everyone,

A few days ago my buddy brought up his sister's m104 (3.2) 300E to have me talk a look at how rough it was running. I'm pretty sure my om617s run smooth than this thing!

When I took a look at the engine bay I found that the water pump had nearly failed and the tensioner shock was on its way out as well.

My buddy got the water pump replaced but didn't have the parts and the car was needed by the end of the week.

So yesterday we went for a ride in it and its still pretty bad. I shot some videos of it and thought I'd post them. I havent had a chance (or the car in front of me) to pull/check codes.

MVI_5607_zps6bda2f16.mp4 Video by JamesDean59 | Photobucket

MVI_5608_zps38d57841.mp4 Video by JamesDean59 | Photobucket

In retrospect these videos might not reveal much. Theres a lot of wind noise from the fan. I also didnt realize the 4,000 rpm limiter existed.

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
Reply With Quote
  #2  
Old 07-13-2013, 06:50 PM
Registered User
 
Join Date: Jan 2012
Posts: 7,534
You didn't say what year, this should have 3 ignition coils on plugs and 3 wires running to the other plugs. These coils fail and will cause roughness. Also, make sure the wires are routed to the proper cylinders. I'd run drive the car, shut it off then pull plugs and look for carbon / wet with fuel.

If the plugs look clean but slightly oily, look for a injector that is not firing.

Another way to test is to start a cold engine then use a heat gun to measure temps at each exhaust port. A dead miss will be cold . ( you can feel for heat if you start with a _COLD_engine that has not run more than a minute. )
Reply With Quote
  #3  
Old 07-13-2013, 06:54 PM
JamesDean's Avatar
Electrical Engineer
 
Join Date: Apr 2005
Location: NE Ohio
Posts: 5,038
Yeah that what we initially suspected was a bad coil pack. This is a 1993 MY.

We replaced the spark plugs not to long ago.

We also found that the 6th plug which is connected directly to the coil pack doesnt seem to "click" in as well as the others.
__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k
Reply With Quote
  #4  
Old 07-14-2013, 12:59 PM
Registered User
 
Join Date: Jan 2004
Location: Jacksonville, FL
Posts: 474
The three spark plug connectors that connect three spark plugs directly to each coil frequently fail and defy detection. It is always a good idea to replace these whenever the plugs are replaced. Also, one coil can fail for either one or both cylinders that are served by this coil. It is easy to diagnose which cylinder(s) are misfiring by disconnecting the electrical plug to each fuel injector while the engine is idling and noting any change in engine roughness and then reconnecting the injector plug and moving on to the next cylinder. Once you have identified the misfiring cylinder, you can swap coil packs and retest to see if the cylinder miss has moved. Mark
Reply With Quote
  #5  
Old 07-19-2013, 05:58 AM
oldsinner111's Avatar
lied to for years
 
Join Date: Nov 2008
Location: Elizabethton, TN
Posts: 6,296
A dirty MAF if it has one will cause rough idle to.I clean mine twice a year.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt
Reply With Quote
Reply

Bookmarks


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 04:35 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page