MB w124 1986, dies on idle

AnuDa

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Mercedes Benz w124 230e 1986 - https://mega.nz/folder/62hkBBjQ#6JGLlR3VLoWGKALeO77Sew
I bought this car April 15 2020. It ran pretty well then, until one day (couple months ago) my mechanic used a pressure washer on everything under the engine cover and beneath the engine as well. My car started to shake when it was on idle a couple of days after that wash day. The shaking came from the engine. I went back to the mechanic and he regulated with something on top the air filter so the idle RPM increased a little above 10. It stopped the shaking and stabilised the car. But there was another issue that happened after the wash, the engine quickly dies after starting it. To keep it alive I had to press on the gas pedal. Whenever it is on idle and low RPM it dies.
Any ideas what is going on with the car? I don't dare to visit that mechanic again.

Thanks in advance! 🌸
 
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ray_hennig

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he regulated with something on top the air filter so the idle RPM increased a little above 10
I feel that a different, more prudent mechanic is your starting point.

If, as I think, he has played with the mixture control (3mm allen key), without knowing what he's doing, he is not the man for the job. Do you see lots of 80s/early 90s Mercedes at his place?

And if he's used the mixture control to increase the idle speed, I fear he's guessing. The idle speed is automatically set.

And jet washing under the bonnet is a risky business as you can damage electronics (few on this car) and get water into the air filter and elsewhere.

I think you need to dry out everything and do a service of the HT system, air filter and general clean up. Then get the mixture control set by someone who knows these older cars - gas analyser/duty cycle checks - not sure on your car..

Sorry to be of not much help.

Good luck from damp, cold France.

RayH
 

optimusprime

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Anu Da Do you have the plastic cover on the coil ? pull it off if you have so you can see the tracking spark on the top of the coil ... Now this is easy .Start the car to night when its dark .I think it is shorting out some place ,,and the sparks will be seen as they track from one electrical item to another . Hope you garage guy did not play with adjustment through the airfilter with a key wrench if he did get him to reverse just what he did .
 
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AnuDa

AnuDa

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Thank you for your reply! 😺

@Rayh He has one MB that is even older than mine. He said that he love Mercedes cars. I reckoned he'd be the guy for the job.
I'll add that to my to-do-list, fix the mixture control by another mechanic that knows. 📋
No more washing under the bonnet. Check! 👌


@optimusprime
I'll check the coil when it becomes dark. Is it the ignition coil? I'm not good with car parts and their names. I have to google the terms and their functions 😳
I could reverse what the mechanic did. It didn't look difficult to do. 😊
Like your user name! 🚚💪

I'm really happy that there's someone quick to reply. I was afraid this would take a week before someone replies.
I've been reading other threads where @optimusprime were viewing and replying. So I've become a little familiar with @optimusprime and was glad that you were among those who replied in this thread.

I'll keep you updated!
Stay safe! ❤️
 

optimusprime

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AnuDa your welcome . But i am only a small cog in this clockwork system . More members will help you if you ask .
Now , you can find the coil by following the king lead from the distributor the [ centre one ] this ht lead will go down to your coil .You might need to remove the plastic shroud .. but look at the whole engine for blueish flashes or off white spark in the dark . Do mind ypur fingers .
 

alabbasi

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Sounds like you have a vacuum leak and he richened the mixture to compensate for the unmetered air. Get it smoke tested (but not through this mechanic).
 

grober

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Because your problems started with an under bonnet wash as RAY suggests it's likely to be high tension damp /moisture problem. Remove the distributor cap it's normally held on by two screws [which need care removing as they can be seized] and check for inner tracking and poor cap contacts and rotor arm corrosion-Everything should be bright metal if not cleanup with a small file/emery paper. Damp can also migrate into the base of the distributor body and this needs to be dried out with a hairdryer for several minutes. Likewise check the coil under its cover as suggested.
ps checking spark plug colour is a good indicator of mixture strength- take care removing the plug connectors as they have built in resistors and are easily damaged without the right tool
 
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AnuDa

AnuDa

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Good evening everyone!

@grober I checked inside of the distributor coil, it looked as if the yellow metallic contacts needed a bit of rub. I used a piece of paper, I don't have emery paper at the moment.

@optimusprime I recorded a video of the entire engine looking for sparks, I also took off the plastic shroud. The video will be pretty dark, but I couldn't see any sparks. Perhaps I did it wrong?
I asked my girlfriend to help me to keep accelerate the car while I was recording from outside. In case you wonder how the car was able to be on while I was outside.

@alabbasi I'll look for a more trusted mechanic to do a smoke check.

@everyone @ray_hennig I recorded two videos, one with checking for sparks and second how the car dies on idle. Check the oil meter as it goes up and down. Anything I should check up?

Here's the link, it is uploaded to MEGA.

Thanks for your replies and thanks in advance for more help! ❤️
 

optimusprime

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Do get the adjustment turned back to where it was to start with if you can . Can you remove the air control valve and clean it out with white spirits .You will need to remove the power plug from the rear, take out the 2 sadle screws then removing the two vacuum hoses from the rear take it out of the car .The two vacuum hoses can get hard and brittle ,but after cleaning the valve make sure hoses are all put back as you removed them . Come back after you have done this . I still think you have a bad spark plug leads or even a bad spark plug .This will make the engine shake .Look in the plug holes for water ..
 
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AnuDa

AnuDa

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@optimusprime I've googled idle air control valve to see where it is located. I should be able to to take it out and clean it. However I am not sure where exactly the power plug is located and how it looks like?
Regarding the spark plugs, I did change them to new Bosch spark plugs. I wasn't sure if I should have changed the spark plug wires as well.

Is the power plug the over voltage relay? I googled it and found this.
1607424791140.png
 

optimusprime

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So give it a shake ..What can you hear ? See the picture of ACV it has a set of pins on the end to take a push on plug thats what you remove .
 
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AnuDa

AnuDa

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@optimusprime The attachment I sent in my previous message wasn't a picture of my car and OVR (over voltage relay). It was a picture I found online to double check with you if I was on the right track. Hence, I haven't been at my car yet. Needed to know for sure if it was the OVR that I was supposed to unplug before taking out the idle air control valve (IACV). Assuming from your reply then it is the OVR that I need to unplug.
Please bear with me, I'm totally green in car parts names and synonyms, and fixing things on my own.

I'll head down soon and start working with the OVR and IACV. I'll give it a shake and let you know. 😸
 

optimusprime

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AnuDa The picture is of a OVP relay over voltage protection relay this relay that you shake ,, you will find it at the back of your battery .It will be at the rear of a plastic shield or cover , you need to take the cover out to find the relay at the back of it .Look for a fuse or fuses on the top of it,check those also . Also the fuel pump relay is in there as well . While in there check contacts on the bottom of both relays .
 
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AnuDa

AnuDa

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I've located the OVP but couldn't locate the IACV, it is probably beneath the Air Filter box. I tried peaking under it with a flashlight from all sides but couldn't locate it. I didn't have the extra time to unscrew the air filter box, I'll do it later today.
I've taken and uploaded pictures of the OVP and the fuse in it. I located another fuse connected between two wires. I didn't have my mobile with me when I was at the car. It looked as if a homemade thing, didn't look original factory made. My guess that the previous owner had something to do with it. I'll take a picture and show it to you later.

49.52 MB folder on MEGA
I'll share the same link again, containing the videos and pictures. I'll add more pictures of this project as we go.

Thanks again for your support! I'm grateful for all help I can get.
 

optimusprime

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AnuDa no need to if it is making a noise it could be the problem . It is easy to open them up and re solder the joints . But it will not last long . Try the acv valve first you will have to remove the air filter box to see it . I bet some of the hoses are toast .
 
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AnuDa

AnuDa

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Hello again @everyone

I've been a bit busy recently, Lucia celebrating and family coming over etc.

Anyway, I've been at my car today and tried to take out the IACV. I wasn't able to understand where to start. I didn't find any screws to unscrew and it seemed to be fixed at its place. I've uploaded pictures on it so you could see, also check out the "toasted" hoses. Maybe you could figure out something and give me advise. In worst case I'll deliver it to a mechanic. I got contact information for an MB enthusiast through a person that work at a junk yard when I called to check for a OVP; which they didn't have. He recommended me a mechanic that would love to work on old MBs. Perhaps I've found the right mechanic for this job. I just hope it won't cost me a fortune.
Anyways, first I will try to fix it myself with your support and guidance. So please check the new pictures I've uploaded to MEGA. It is the same link that I've shared before in the thread. There's also additional pictures on a red fuse that I have no idea if it was mcgyvered there or if it is originally like that?

Thank you in advance!
 

optimusprime

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The fuse is from the top of the OVP relay, if it is ok put the fuse back in place on the top of the relayput it back in place . I can see your stuck finding the IACV now you wont see or find it untill you remove the air filter box look at my picture of iacv .,.Let us know when you find the iacv . Take a picture of the parts --nuts or bolts and hoses you remove so you will know how to replace them . Do this first -- remove air filter box and find the IACV . And i bet you will find split or bad vacuum hoses .
 

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