[chatomon]

Hello,

I apologize for my English.

I have a w202 220 which has some problems and unfortunately in France, it is not the country of gasoline. People don't know the 220 engine

My car is from 1993 with 236,000 Km (+/- 145.000 miles)


When I bought it (I took 4 hours to get to my house) it worked very well except the idle engine at the stop (500 rpm and car trembling and hard start when the car is hot)

Fuel gauge, RPM meter and water temperature do not work.

After 5 to 10 minutes, the fuel gauge and RPM meter works.

I did the engine and box drain. I set the idle with the screw on the picture.

The idle is better at cold but warm when I stopped the car a few minutes, very hard to start and the idle holds hard.
Besides, I have no more power. I accelerate and the engine rises to 1,500 rpm and goes down to 1,000 in the second.
It is impossible to drive.

I was advised to change the K40 relay.

Do you have an idea ?

Could it be a temperature sensor? The flowmeter?

Thank you in advance for your help and still apologies for my bad English.

Regards

 

[Patman1]

Alright, we will try to work through some of these issues. If there is something you don't understand, PM me, I do speak French.

The screw you adjusted does not change the idle speed. You simply made the cable too tight and it is opening the throttle body. The idle is controlled electronically by the throttle body, but for that, the throttle plate must be in the fully closed position. There is a small switch on the throttle body that is pressed when the throttle is closed, which allows the computer to take over the idle control.

Now, pre 1997 cars had a problem with biodegradeable wiring harnesses. In particular, the affected wiring harnesses were the engine main harness, the ignition harness, and the throttle body harness. I would inspect all the wires near the engine for signs of degradation. The throttle body harness has an extra layer around it, but that didn't save the wires inside. You might have to cut the outer layer open to reveal the damaged wires inside. So that's the first thing I would check.

Your car does not have a K40 relay, however, it has the OVP relay which has the same function as the K40 (although the OVP relay is just a relay, not a relay + fusebox combination). Replacing the OVP relay is a good thing to do when buying an old MB. There is a plastic cover on the passenger side of the engine, if you lift that up, you will find the electronics compartment. The OVP relay is silver, with a 15A fuse on top. If the fuse is hidden by a round cover, chances are it's the original relay, which had a manufacturing defect.

The next thing I would do is inspect all visible vacuum lines and connections for any leaks. I would also check the fuel pressure regulator vacuum line for leaking fuel. There should not be any fuel in that vacuum line, if there is, that's a sign of a failed fuel pressure regulator.

Finally, I would replace the spark plugs, the condition of the old ones can tell you a lot about what is going on with the engine. There is tons of information on this forum, do a few searches, do a little bit of reading, I'm sure you could find all the problems and easily fix them yourself!

 

[chatomon]

Hello,

Thank you for your quick and precise answer.

I tried to send you a PM but I don't how to do it. No problem, it will make me work my English

For the screw, I'm talking about the black plastic screw and when I move it, the idle increases or decreases.

I saw that there is an electronic system for idling. Maybe due to the problems I just discovered today.

The electric cables (as you think) are damaged. The insulation is gone. These are the temperature probe cables and the injector cables. I have not yet looked at everything so may be other surprises.

So I will fix and have it on a clean basis and hope that's the problem.

I thought it was called a K40 relay but effetively it is silver with a 15A fuse.
I will first repair the cables before changing this relay.


Thank you very much for your help. I come back with good news, I hope early week.

Have a good day and again a big thank you for all this complete and valuable information.

Regards

 

[Patman1]

No problem! I think re-wiring/replacing the damaged cables will fix everything. The ignition harness is really cheap, so I would just buy a new one. The throttle body harness is likely also damaged. Unfortunately, the wiring is soldered to the throttle body electronics, so you can't just easily replace the wires. You can find a used throttle body with the updated wiring (it should be manufactured after 2006), that would probably be the most cost effective solution. For the main harness, either have a company rewire it, or replace it.

The black plastic nut should only be used to remove the slack in the throttle cable, it should not be used to set the idle, so that means it's way too tight. Like I said, idle is controlled electronically, but in order for the idle circuit to be working, the throttle plate must be allowed to fully close, pressing on the switch. If the engine stalls with the throttle cable properly adjusted, that points to an issue with the throttle body (specifically the wires, which suffer the same degradation as the others).

The K40 relay is present on cars starting model year 1997, when Mercedes switched to Bosch ME-SFI, earlier systems, like HFM-SFI on your car, used a simple OVP relay.

Also, a healthy engine with no vacuum leaks will idle at 500 rpm in D in automatic cars. Manual cars probably idle a little bit higher, somewhere around 600-700.

 

[chatomon]

Hello,

Thank you for all these explanations. I attack repairs today.

Feedback as soon as everything is repaired.

Have a good day

 

[chatomon]

I forgot to ask you. Do you have the throttle body reference with the updated wiring?

Thank you

 

[Jostep]

Had the same issues with my 95 c220, lot of info in the thread "new member, new project lots of questions"

My car had the wiring harness replaced, but they did not fix the throttle body, swapping that part out, fixing the multiple vacuum leaks (tiny but added together made a decent leak.). Fuel pressure regulator, coils, plugs, and plug wires with fresh fluids got me 29 mpg and nearly factory new power levels. Add in the fact that car already has 179k plus worth of mileage and that's a win...

Pics to show what you're dealing with.

Toasted Wiring harness #1
Old part number of throttle body

 

[Jostep]

Had the same issues with my 95 c220, lot of info in the thread "new member, new project lots of questions"

My car had the wiring harness replaced, but they did not fix the throttle body, swapping that part out, fixing the multiple vacuum leaks (tiny but added together made a decent leak.). Fuel pressure regulator, coils, plugs, and plug wires with fresh fluids got me 29 mpg and nearly factory new power levels. Add in the fact that car already has 179k plus worth of mileage and that's a win...

Pics to show what you're dealing with.

Toasted Wiring harness #1
Old part number of throttle body #2
Vacuum schematic. #3
Finished product which you absolutely can do. #4

Btw new part # with updated wiring for the throttle body is 0001416525

 

[Patman1]

I would've painted my valve cover too, but TBH it's so filthy that it would need to be sand blasted before it could be paintable. I cleaned it from oil and grime, but its still got dark spots that won't come off with a wire brush.

BTW Jostep, you are missing the plastic front cover that hides all the wiring above the thermostat manifold (or did you just remove it to take the pic?) I painted mine gloss black

 

[Jostep]

I know, I have it, just not a pic of it installed. To lazy to go take a new picture.

Speaking of covers, did MB have one over the brake booster drivers side well like they do for the passenger side electronics?

And I did sandblast mine, then parts washed in solvent, offgassed and sprayed/baked with a hi temp ceramic coating. Worth the effort but not the cost. I should have just polished it.

 

[chatomon]

Hello gentlemen,

Thanks to Jostep for the explanations and photos.

I started yesterday the cables. It is a crazy job but with calm it goes well. I hope I do not make a mistake.

Do you have the same schema for electric wiring as for air?

I am looking for some plugs (because the insulation of the cables is broken even at the base of the plug) The round plug above the thermostat manifold
(The third from right to left) and most certainly those of the throttle body.
I found nothing on the internet. Do you think Mercedes sell these parts without the cables?

A very big thank you for your help and your answers.

I wish you a good day.

 

[Jostep]

No problem, Patman1 nailed your problem...just providing some pics and a bit of encouragement hopefully.

No wiring diagram, I've got the M111 4 cylinder in a c220...1995 model.

Don't be super concerned, typical problems, tons of info right here on how to fix it. And I've got my hands dirty spinning wrenches on almost everything...from 1900 steam engines, to muscle cars and modern day diesels. These little guys are really simple, and the engineering that went into not only building them, but working on them is absolutely the best.

My standard warning though... that plastic nut on your throttle cable is the only piece of cost cutting garbage I've found, it breaks unbelievably easy and in my opinion is poorly engineered. Be very careful with adjusting it, and the throttle micro switch adjustments once you have a new throttle body installed are very important.

I'll try and track down the procedure, I believe mine covers the m111 and m104 setups.

BTW if your plug wire insulation is that damaged...that's going to fix a lot of issues, and get you running again nicely. I've found that it usually isn't just one thing that has been neglected, it's a collection of little things that add up to a weird multi symptom problem.... just examine, test, and give everything a good inspection.. and get a tool called a mityvac. It will absolutely pay for itself with tracking down vacuum leaks you didn't even know you had. Or if it isn't available, just replace all the rubber vacuum lines...it's cheap. The nylon hose is usually fine, but the rubber ends are shot. Then you can take spark and vacuum leaks out of the equation once you pop,in fresh plugs.

Have you checked for stored codes yet?

 

[chatomon]

Hello Jostep,

I have not the computer to test the errors so I can not say anything on this side.

I thought to buy a stardiag but it will be for later.

Thank you for your help and encouragement.

I finished two cables and am busy on the main.
I hope to have finished tomorrow night. As I have other parts to change (water pump, .......) arriving tomorrow or Thursday I hope to have it all finished Thursday night and give you good news.

I am impatient.

Thank you for your help.

 

[Jostep]

For some reason I thought you had a 280 with the 6 cyl... carry on then, nothing changes, just gets cheaper:grin

 

[Patman1]

Just a word of caution when choosing spark plug wires. Finding original (Beru) wires might be difficult. Genuine MB wires are probably expensive (and I believe you actually have to build them yourself). Stay away from Bosch spark plug wires! I know normally Bosch is an excellent company, but every good company has a dud once in a while. Their spark plug wires simply aren't good! I've had a wire break after 2 years! The best alternative (which I am currently using) is Karlyn-STI. They are a more generic set, the wires are longer, but they are built extremely well and come with a few clips to help keep the wires tidy.

EDIT: I just realized what you probably meant by "plugs" are the connectors to each sensor. In which case, I'm not sure if they are sold separately. I know for some of the larger plugs (like some of the interior stuff) can be bought separately. It's worth a try, so go to your local dealership and ask! They are usually really helpful.

 

[chatomon]

@ Jostep

No just a 4 cyl 2.2

@ Patman1

Yes the plug for the temperature give me problem. Let's go to continue the repairs this morning

Thanks for your help

Have a good day

 

[chatomon]

Here it is almost finished everything is in its place or almost.

In any case, it turns. The idle is better but not flawless.

I still have to do the water pump and two three things and tomorrow end of the day, road test.

I hope it'll be ok.

Feedback tomorrow.

Thanks to those who helped me.

 

[chatomon]

Hello everyone,

Work almost finished, there are some details but I test and drive the car.

Everything goes almost right.

The idle is much better even if it takes a few seconds to stabilize.

At a few moments it is a bit low but with the air conditioning so let's say it's better and it does not make the whole car tremble anymore.

But I still have the dashboard problem.

RPM sets out only after a certain time.
Fuel and temperature does not work.

Do you have an idea where to look?

Thank you in advance.
And a big thank you for your help regarding the first problem.

Regards

 

[chatomon]

Hello everyone,

I got there, everything went up.

The summary is:

- Cold motor: Very slow idle (the famous black screw set to minimum for the idle regulator to be closed)
- Hot engine: much better.
- No more hot start problems.
- Some trembling problems when even at idle (I really think the idle is low especially with the A / C)
- But the new concern. During two kick downs the engine is not mounted at more than 4,000 RPM (as if the breaker (not sure of the English word) was starting). By releasing the accelerator, the gearbox change de speed and everything is good but problem anyway on this side (not all the time)

Do you have a idee to follow?

Thank you for your help.

Regards

 

[Jostep]

Bowden cable adjustment, easy fix and no parts to purchase:grin

It's the rubber enclosed spring looking cable attached to the rear of the throttle linkage arm. It runs straight back to the firewall and down to the transmission, located on intake side of motor.

Simply back the screw off a few turns and it "tells" the transmission how much throttle is being applied. Right now part throttle feels like full throttle as the cable is set to tightly.