w124 with carburetor - some problems

[vlado1991]

Hi guys. As I said before, I would like to introduce you some problems I have with my mercedes. I would start with the (for me) biggest one.
Choke actuator have some strange behavior. The flap is constantly shaking which cause unstable idle work. In summer times it is usually possible to start the cold engine without touching manually the flap. In winter, especially in the mornings, there are no chances at all to start it without closing the flap with the hands. This is a little annoying, but ive made some practical solution. Put the pencil near the needle that holds flap, and when engine gets warm it automatically opens flap. And, because i've wrote a lot here, and people says that one picture (video) worths thousand of words, i have made a video of problem, so you can see exactly where the problem is. Here comes the link.
https://www.youtube.com/watch?v=bysINYaJUY8

Any suggestions where could be the problem? Heat sensor, wiring, choke actuator, or the control unit?

 

[vlado1991]

As I thought so Nobody cant solve my problem

 

[grober]

The symptoms suggest that some form of small spring which should be tensioning/damping the choke butterfly plate is broken/missing /detached ?

If the carburettor is the Pierburg 2E-E as the pictures suggest perhaps these diagrams may be of some help - in particular the ones at the end.
PIERBURG 2E-E - 2EE VW+DB Ersatzteilliste Vergaser

item 21 perhaps?

 

[vlado1991]

no. I removed the small engine that moves the flap, and then start the car (but still connected on electricity). You can see and then that the small engine have the same work. That indicates the spring is correct and the flap also. The current that comes to the small engine is probably with the wrong value, or the engine is dead. Just the problem is what causes the wrong value of current. Sensor, or Control unit. And, i dont know how to check that

 

[grober]

OK I get what you are saying. you feel its an electrical problem. I'm not sure if the UK market ever got engines with this particular carburettor. I believe this carburettor had its own small ECU with inputs from temperature sensors and possibly the lambda sensor. This would point to a possible ECU fault or maybe sensor failure or even an instability in ECU supply. Many w124 of that age suffered problems with the OVP [ OVERVOLTAGE PROTECTION RELAY] Poor pin contacts or dry joints on the small internal circuit board [ these can sometimes be repaired by resoldering the component connections to the board. ] or simply replacing the relay. If your car has an OVP relay which provides 12V to the Pierburg ECU I would look very closely at the voltage its putting out and maybe repair/ replace it?

This document in German describes some of the electrical circuit tests that can be done.
Sevice Anweisung2E-E VW

 

[vlado1991]

Well, that's something i haven't tried. I have some control unit behind the battery, all of cables goes from there, and there are some relays behind the fuses. Where is located that OVP? One is also near the control unit, but i think that is for ABS. And yes, mine w124 had lambda sonda (later removed, together with the catalyst converter in exhaust system).

 

[vlado1991]

Sorry for "afterpost", i've found this document in german before, and checked that "drosselklapen-potentiometer" with the ohmmeter, and values were correct.

 

[grober]

Well, that's something i haven't tried. I have some control unit behind the battery, all of cables goes from there, and there are some relays behind the fuses. Where is located that OVP? One is also near the control unit, but i think that is for ABS. And yes, mine w124 had lambda sonda (later removed, together with the catalyst converter in exhaust system).

The OVP relay is usually located close to the engine ECU and ABS controllers and can be indentified by one or two fuses on the top [ these may be concealed by a cover]

 

[grober]

Took a bit of finding but found this description of the Pierburg 2E-E as fitted to the Mercedes 2 litre engine Russian site- zipped document in English.
You won't get better info than this.

http://www.google.co.uk/url?sa=t&rc...VcmBGIL5sI1JHIw&bvm=bv.88198703,d.d24&cad=rja

 

[vlado1991]

Thanks on being interested in my problem! Tomorrow i will remove the relay and try with another one, to see does it changes something. Thank you on this document, looks like i can learn something from that. I will read all of it and look for suspicious items.
And youre right, i doubt that i'll get any other info than you gave me, on a lot of forums ive posted my problem, and you gave the most solutions! Thank you on that! You have a beer from me when you come to Montenegro! Cheers!

 

[grober]

I found this thread also on another forum which discusses problems with this carb. In that case it tirned out to be broken connections in the N45 ECU which were repaired by resoldering
Pierburg carb on a w124 200 Problem [Archive] - Mercedes-Benz Owners' Forums

part nos for the N45 ECOTRONIC UNITS are

A0065454332 prekat

A0065455132 with kat

last issue A0085458832 with kat

altho it would appear that the pre and post cat internal ECU MAPS can be selected by different resistances across a couple of the ECU pins.

e.g.
http://www.tav-autoverwertung.de/sh...8545883202-Bosch-0285007056-Pierburg-71816558

 

[dinoy]

the w124 mercedes 200 200t (not 200 te) use carburtor model and might be easier to source complete carburtor.

there are peburg recondition kits for vw gold 1.6 and 1.8 there might be kits for 2 litre if used elsewhere.

but i am sure w124 breakers will sell carbs

look at this the makers might be able to help

UNIVERSAL 12V FUEL PUMP + 2X FUEL UNIONS + IN-LINE FUEL FILTER PETROL & DIESEL | eBay

and these repair kits

http://www.ebay.co.uk/itm/Mk1-Mk2-G...867?pt=LH_DefaultDomain_3&hash=item25a1373d2b

 

[vlado1991]

Checked and replaced with the new one, this relay, and the same happened. Next thing I am going to do, is to take the Control Unit to the TV repairman. Will be in touch.