Idleing problem w124 200E
Posted on 08-16-2011 02:16
I have W124 200E engine type 102 936 (M111) from 1995. I have (had) problem with throttle valve. Engine was not running smoothly when idle, reader increase and decrease all the time. Also, when engine was cold it was shutting down immediately by it self when my foot was off the gas paddle. Yesterday I open the throttle body clean the butterfly valve and put contact spray on the electric sliding contact on the butterfly shaft, put silicon seal and tune precisely valve opening for idling position on around 700-800 rotation per minute and close the throttle body. When I start engine (it was still worm) it was running Very smoothly, like never before (I have it 1 year). Today was even better; probably reaction from contact spry was still going on during the night. But when engine is cold I still have problem because is shutting down when Iím not pressing the gas paddle. This is like 3-5 min and after that time the engine is running nice. So I suspect two things to be possible problem.
First, Air Flow Sensor, there is very big possibility that sensor is not working; (because I broke it) I was cleaning it, and since is bi-metal type (or it was broken before, because wires were split) probably I change the distance between contacts.
I test the Mas Air Flow sensor, it give strange readings.
I use hair drier to blow in the sensor while it was connected to the Ohm meter. The readings were not constant. I notice sharp change in the value with no obvious reason (no change in the direction of the hair drier). After that I tested it on the car after I warmed up the sensor while engine was cold, I notice some difference, car was idling (before was shooting down instantly after i take foot of the pedal) but for about 10 seconds, becoming worst after every second past. I'm thinking that warm sensor gives better reading and as was cooling the readings becoming inappropriate that lead to engine shut down.
One mechanic promise me that he will try to find sensor (from other car) just to test it so I'll cheek with him today and if I do something I'll update you
Second, failure in the insulation of the wires that come out from throttle body (like problem on this post here (http://www.motor-talk.de/.../...ine-drosselklappe-spinnt-t3018832.html) because I have the same throttle valve.
Probably there is probability to be problem with the electro-motor in the throttle body, or in the gasoline valve for the cold start, purge valve, vacuum pipes etc. (last two I cheek visually and purge valve also by shaking it and blowing/sucking in it, but not in details).
I will appreciate if some one can explain me how much Mass Air Flow sensor it can influence the steadiness of the running of cold engine when idle (since I read that by reading the temperature of the air computer can estimate the content of the oxygen (O2) in the air and use this information in regulating butterfly valve opening when engine is running cold). I suggest that since I change the distance between the two wires in the sensor now the computer receive falls information and can't open the valve as needed.
If this is not a case how to check if there is problem in the insulation of the wires coming out from throttle body (I can use Ohm-matter, but I donít know is there should be a contact between some wires or there should not be any contact between wires). Also in this picture ( http://www.motor-...76665.html ) on the left side (after "H" and "A" there are two wires without explanation how to reconnect, since this is DC electricity changing the polarity means changing the direction of the electro-motor which will lead in closing instead of opening the butterfly valve.
Sorry for so long post.
I hope that some one can help me
all best from Macedonia
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