RPM dipping at slow rolling - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 31 (permalink) Old 05-10-2016, 03:33 AM Thread Starter
BenzWorld Senior Member
 
Gripen's Avatar
 
Date registered: Apr 2014
Vehicle: 1994 E280
Location: Netherlands
Posts: 434
Mentioned: 0 Post(s)
Quoted: 59 Post(s)
(Thread Starter)
RPM dipping at slow rolling

I've posted before about this but I can't get it sorted and want to try again and see if anyone has another suggestion:

First off, the car runs pretty great, idles smoothly.

The 'problem' occurs most of the time when doing one of the following examples:

1. Start car, put car in R (reverse) and drive back a few meters with a little bit of gas and just release the gas pedal completely. The car dips to like 500 rpm and shakes a little.

2. Driving normally coming to a traffic light, I release the gas pedal and brake slowly. While almost coming to a standstill it dips to like 500 rpm and starts shaking.

3. When I drive / roll really slowly and turn into a parking spot and I turn the steering wheel TOTALLY to one of the edges it dips to like 500 rpm and starts shaking.

Now, when it does that... if I press the brake pedal totally and stand still it instantly recovers to what the RPM should be at standstill.

When I disconnect the battery for a while and connect it again it seems to be away for 1 or 2 days.

M104 2.8
722.433

Any idea where to start?

Last edited by Gripen; 05-10-2016 at 03:36 AM.
Gripen is offline  
Sponsored Links
Advertisement
 
post #2 of 31 (permalink) Old 05-10-2016, 05:19 AM
BenzWorld Elite
 
sbaert's Avatar
 
Date registered: Jun 2007
Vehicle: '95 E300 DIESEL, '91 600SEL, '92 600SEL
Location: San Diego/USA & Belgium/Europe
Posts: 16,529
Mentioned: 27 Post(s)
Quoted: 1848 Post(s)
The first place I'd look at is to check for & eliminate any vacuum leaks. I had a very similar, if not identical issue, when I got the first 600SEL. Turned out to be a aged rubber coupling at the transmission that was causing loss of vacuum. Replacement cost: 1.29 Euro

Another thing, when you went through your ETA replacements due to eco junk wiring did you install a brand new gasket prior to installing the throttle body???
Gripen likes this.

Last edited by sbaert; 05-10-2016 at 05:22 AM.
sbaert is offline  
post #3 of 31 (permalink) Old 05-10-2016, 05:42 AM Thread Starter
BenzWorld Senior Member
 
Gripen's Avatar
 
Date registered: Apr 2014
Vehicle: 1994 E280
Location: Netherlands
Posts: 434
Mentioned: 0 Post(s)
Quoted: 59 Post(s)
(Thread Starter)
Yeah I ordered a new Elring gasket and made sure it was fit correctly! Of course I could have messed it up, is there a way to test this? Something like spray brake cleaner around the ETA and see if it stars dipping/surging?

I have a feeling what you are saying about the vacuum of the transmission might be true. I'm not too familiar with the vacuum system to/from the transmission but I can do some research which I will do tonight.

The transmission also feels a bit weird, ever since I got it. Like, you drive and when it wants to shift, you can feel that it is GOING TO shift but it waits a little bit too long, like softly braking and then it goes into the next gear and all is smooth again. I feel like this might also have to do with the loud whirring at startup (cold) and maybe my weak braking.

I'm gonna go and see if I can get some more information on these vacuum couplings!
Thanks Steve!

Last edited by Gripen; 05-10-2016 at 05:54 AM.
Gripen is offline  
Sponsored Links
Advertisement
 
post #4 of 31 (permalink) Old 05-10-2016, 06:19 AM
Moderator
 
Jayare's Avatar
 
Date registered: Jun 2005
Vehicle: 86 190E 2.3L 16V, 2 95 320TE's, 02 S500
Location: Seminole, FL
Posts: 12,494
Mentioned: 10 Post(s)
Quoted: 1089 Post(s)
Lifetime Premium Member
What is your voltage at the battery, at idle rpm?
Jayare is offline  
post #5 of 31 (permalink) Old 05-10-2016, 06:23 AM
BenzWorld Elite
 
sbaert's Avatar
 
Date registered: Jun 2007
Vehicle: '95 E300 DIESEL, '91 600SEL, '92 600SEL
Location: San Diego/USA & Belgium/Europe
Posts: 16,529
Mentioned: 27 Post(s)
Quoted: 1848 Post(s)
The ETA gasket is pretty hard to mess up during install. The only 3 things I have seen is 1) not replacing the gasket, 2) when people do not clean the mating surface on the intake manifold meticulously causing a instant leak followed by 3) not lining up the gasket correctly.

When installed properly, the throttle body gasket is pretty much good forever or until the next time the throttle body needs to be removed.

As far as the vacuum system, I highly suggest you get yourself a little handvacuum pump kit such as a Mity Vac. Worth its weight in gold for older gen MBs.

For the odd shifting behavior, sounds like you need to check and/or adjust the transmission pressure control cable.

The loud whirring noise at startup is most likely the air pump, part of the emissions equipment to help catalytic converter warmup.

https://www.amazon.co.uk/Mityvac-Pressure-Pump-Vacuum/dp/B001NZ1WSU/ref=sr_1_12?ie=UTF8&qid=1462886560&sr=8-12&keywords=mityvac

Last edited by sbaert; 05-10-2016 at 06:26 AM.
sbaert is offline  
post #6 of 31 (permalink) Old 05-10-2016, 06:24 AM Thread Starter
BenzWorld Senior Member
 
Gripen's Avatar
 
Date registered: Apr 2014
Vehicle: 1994 E280
Location: Netherlands
Posts: 434
Mentioned: 0 Post(s)
Quoted: 59 Post(s)
(Thread Starter)
@Jayare :
I need to check that. Just put a Multimeter on it? black on - and red on + of the battery, am I right?
Just making sure...
@sbaert :
Then the gasket should be fine. If the car is warm it's smooth as can be.

I don't think I have an air pump, it should be above the alternator right? Isn't there
It's really loud. My dad always shakes his head when I leave their home he always says "Wat joelt dat ding toch, kan niet goed zijn"

As for the mitivac, it's pretty expensive so I will wait a bit with that. I understand it's worth it but I'm not just gonna buy everything, I'll save it on the wanted list

Last edited by Gripen; 05-10-2016 at 06:29 AM.
Gripen is offline  
post #7 of 31 (permalink) Old 05-10-2016, 06:29 AM
BenzWorld Elite
 
sbaert's Avatar
 
Date registered: Jun 2007
Vehicle: '95 E300 DIESEL, '91 600SEL, '92 600SEL
Location: San Diego/USA & Belgium/Europe
Posts: 16,529
Mentioned: 27 Post(s)
Quoted: 1848 Post(s)
Quote:
Originally Posted by Gripen View Post
....
It's really loud. My dad always shakes his head when I leave their home he always says "Wat joelt dat ding toch, kan niet goed zijn"
Then it is probably just audible confirmation that your viscous fan clutch is fully operational.
sbaert is offline  
post #8 of 31 (permalink) Old 05-10-2016, 06:32 AM Thread Starter
BenzWorld Senior Member
 
Gripen's Avatar
 
Date registered: Apr 2014
Vehicle: 1994 E280
Location: Netherlands
Posts: 434
Mentioned: 0 Post(s)
Quoted: 59 Post(s)
(Thread Starter)
Quote:
Originally Posted by sbaert View Post
Then it is probably just audible confirmation that your viscous fan clutch is fully operational.
I don't understand what you mean or if it's a joke.
The engine is cold so viscous fan clutch will not engage right?

I have to say, it only does this if the engine is cold. If the engine is still hot it won't do the whirring.

Anyway I'll test the battery voltage first and report back. 2 more hours of working
Gripen is offline  
post #9 of 31 (permalink) Old 05-10-2016, 06:34 AM
BenzWorld Elite
 
sbaert's Avatar
 
Date registered: Jun 2007
Vehicle: '95 E300 DIESEL, '91 600SEL, '92 600SEL
Location: San Diego/USA & Belgium/Europe
Posts: 16,529
Mentioned: 27 Post(s)
Quoted: 1848 Post(s)
Here is a very cheap vacuum tester kit. Does miracles when hunting down vacuum issues

https://www.amazon.co.uk/Sealey-Vacuum-Tester-Bleeding-Complete/dp/B000RO612A/ref=pd_sim_sbs_60_3?ie=UTF8&dpID=414AK258ynL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=9Z2VD8PB6BBT11S2GBSZ
sbaert is offline  
post #10 of 31 (permalink) Old 05-10-2016, 06:44 AM Thread Starter
BenzWorld Senior Member
 
Gripen's Avatar
 
Date registered: Apr 2014
Vehicle: 1994 E280
Location: Netherlands
Posts: 434
Mentioned: 0 Post(s)
Quoted: 59 Post(s)
(Thread Starter)
Ordered!! :-)
Thanks for providing the link for it sbaert!!
Gripen is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W124 E,CE,D,TD Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome