Welcome Guest [Log In] [Register]
Photobucket
Welcome to Mercedes-190.co.uk

We are the Mercedes 190 owners forum, the place to be for all owners and fans of the Mercedes 190E, 190 and 190D cars. Including Cosworth (2.3 16v and 2.5 16v), EVO 1 and EVO 2 models. Modified and concourse, track cars and daily drivers, all are welcome.

This free UK based forum was started back in November 2005 to serve the Mercedes 190 W201 community and now has over 9000 members from all around the world and 600,000 + posts.

The members welcome you and encourage you to stay a while and have a look around.
We offer you friendly chat and access to some very useful information as well as tutorials with photos and videos for many common repair and maintenance jobs.
Whatever your needs there is a good chance you will be able to find what your looking for. Such as our Mercedes 190 buyers guide

Sign up to gain access to all areas including for sale / classified areas and country wide meetings and events. Many forum features and sections are only available once you sign up.

Join our forum at mercedes-190.co.uk!

If you're already a member please log in to your account:

**New members signing up**
please check your junk mail for the email authorization email
otherwise we cannot verify your new account.
I have noticed a lot of unauthorized accounts in the system.
Regards
Admin

Username:   Password:
Add Reply
Harsh auto shift - vacuum issue?; Auto changes gear sharply - vacuum tube not connected
Topic Started: Mon Aug 6, 2012 1:46 pm (2,714 Views)
Ericsawbo
Newbie
[ * ]
Hi all,

My auto is very keen to get goining once it's in gear, and the gear change is also pretty harsh. I'm guessing it's one of two things:

1) I have heard that a harsh gear change on an auto can be helped by twisting the vacuum modulator on the transmission - I found that but it's very difficult to turn (you turn the teeth on the modulator). Has anyone got a good tool/ tips to help with this job?

2) I later found the vacuum tube from the transmission itself is loose. Does anyone know where the tube should join to? Mine is not connected at all, and the only place I can see where it might attach is at the top of the engine block. I guess I need to buy a replacement vacuum tube and rubber connectors? Is there a special process for reinstalling?

Any comments would be great!

thanks v much

Eric

Offline Profile Quote Post Goto Top
 
Ericsawbo
Newbie
[ * ]
Well no replies so far, so I guess you're all as confused as me! I'll give you an update though as I've made some progress...

The loose vacuum tube I found now runs from the transmission to a vacuum port at the back side of the fuel distributor. If you ever need to do this, first take off the whole air filter assembly as you wont be able to see it without doing this (and hence my problem!)

This solved a fair but of the problem, and is well worth checking if you have an agressive gear change.

The other issue was how to change the actual vacuum amount going into the transmission to fine tune the gear change sharpness. I had tried to turn the teeth on the modulator itself which can be found by removing a black rubber cap in the centre (mine is a red modulator, but they are often green and are on the passenger side of the transmission tucked quite far around). It turns out that you can't turn the teeth, but need to instead turn a small key which slots between the teeth. No surprises then that I couldn't turn the teeth!

So, if you want to fine tune your gear changes (also firms up gear changes if you need), first get under the car towards the front, passenger side to find the coloured modulator. Make sure the line is actually connected, and if it is, take off the rubber top with a pair of pliers. Pull the metal T shaped key out just enough to turn and turn anticlockwise to reduce gear change sharpness, or clockwise to increase sharpness. Try one turn, replace the rubber top and give it a go! If it means anything to you (means nothing to me!) one full turn alters the pressure by 0.4 bar.

happy modulating!
Offline Profile Quote Post Goto Top
 
OneNineTee
BANNED
[ *  * ]
Excellent, thanks for that information.

Vaccum leaks can be the cause of many issues! My old 1.8 before this one blew a hose off and wouldn't set to idle. Easily fixed when you're in the know.

I'm sure many members will benefit from this posting.
Offline Profile Quote Post Goto Top
 
scherrit
Part of things
[ *  * ]
thanks for this, my neck is in danger of being broken when the transmission is in sport mode. will have a fiddle tomorrow.
Offline Profile Quote Post Goto Top
 
Gnasha
Member Avatar
More than part of things
[ *  *  * ]
thanks Eric ill give this a try some time, I'm experiencing sharp changes going to 1st and reverse, the rest are ok
Offline Profile Quote Post Goto Top
 
Gnasha
Member Avatar
More than part of things
[ *  *  * ]
Gnasha
Sun Jun 21, 2015 8:21 pm
thanks Eric ill give this a try some time, I'm experiencing sharp changes going to 1st and reverse, the rest are ok
https://www.youtube.com/watch?v=gM4KZvwsCW0

I think this is it good explanation but still difficult to adjust from an access perspective
Offline Profile Quote Post Goto Top
 
ammar786
Part of things
[ *  * ]
where is the vacuum modulater
on the gearbox or on the engine, any pictures?
Offline Profile Quote Post Goto Top
 
eagle3
Therapy Needed
[ *  *  *  *  *  * ]
On the gearbox. https://mercedessource.com/problems/transmission/diagnosing-adjusting-and-fine-tuning-mercedes-automatic-transmissions
Offline Profile Quote Post Goto Top
 
Gnasha
Member Avatar
More than part of things
[ *  *  * ]
or try this https://www.youtube.com/watch?v=gM4KZvwsCW0

I'm about to try adjusting my own modulator the "green" type asap, it snatches from neutral to forward gear and same to reverse


let me know how you get on :driver:
Offline Profile Quote Post Goto Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
« Previous Topic · Gearbox & Clutch · Next Topic »
Add Reply


Email me if anyone replys