1990 190E 2.6
 

My sons car is not behaving, bad idel and stalls. Car sounds like it is missing, smells like its running rich. He just had new plugs put in not too long ago but I took them out to have a look at them and I am glad I did. They where caked with black carbon, so I put new ones in and the car started. (before new plugs car would not start) It started but ran like crap and wanted to die.

I was going to take it for a drive but wont start now, when it did start it smelled rich like to much fuel. I think I am going to replace the oxygen sensor and new plug wires, what else should I be looking at? Car has 204,000 miles on it, thanks. Also, when I turn the key but not try to start the car, should I be able to hear the fuel pump?

yes you should hear the pump untill it pressured up. Far to much fuel, first the lamda gets its reading from the temp sensor, and the ox, sensor. those two send a signal to the EHA, little black object with wires on the side of the throtle body. somthing is telling the EHA to pour the fuel to the system! replace them both cheap insurence. Do you know how to use a multimeter? if so check post two and three plenty of postings on this get you percentage to 50% should clean up and run well.

Also, check to make sure the EHA isn't leaking. I have an extra that is used if you want to buy one. They are about $250-$300, not cheap, so I would start with the simple stuff first, because usually you can tell when the EHA goes bad because it will leak and you will be able to smell the fuel as well as feel is from where it is leaking from.

What is the EHA? And where is it?

This is from a February 2001 article by Steve Brotherton, an MB tech at Continental Imports from ImportCar online magazine.

“The EHA is the final servo device for applying the corrections intended by the control system. All forms of enrichment are accomplished by increasing the differential pressure within the fuel distributor. The EHA acts as a controlled leak depending on current. Positive current flows cause enrichened mixtures by leaking down the lower chamber pressure (higher differential pressure). Negative current flows cause lean mixtures and, on deceleration, a negative 60ma causes fuel shut-off.�

As you can see if the valve is sticking, damaged,leaking, or otherwise not working correctly, the adjustments needed for the engine to run smoothly are not taking place which may result in a rough or high idle, hard starting, stalling, and poor acceleration.

Look under the air filter housing attached to the back of the fuel distributor. It has a plug going to it and is bolted on by 2 bolts. Mine were hex bolts, but may also be flat head bolts. Google w201 eha valve and look at the images so you know what it looks like.

First start with replacing the overvoltage protection relay (OVP), they all break, its fact....Stalling + missing are all symptoms.

Next ensure you have a fluctuating duty cycle at the X11 plug. Do a search on these forums for it. Don't worry about the EHA until you have established that the system is in closed-loop.

I have a spare ovp and switched them out and nothing changed, I will search the x11 plug next. Thanks.

Been there and done that with a 190e 2.6.

Do a leak down test. I would almost bet that the valve seals need replacing.

That would cause bad idel? When it does run it sounds like its missing, and you can smell fuel. When you push on the gas peddle it is allmost like you have to do it slow or it bogs down, like its getting too much fuel.

A leakdown test will not necessarily indicate bad valve seals -- only worn valves. If you are burning oil, the valve stem seals are leaking, that's about it....no leakdown required.

You'll see black deposits on the spark plugs. I don't think thats the issue here though as you'd know if you were burning oil as you'd be topping up every 500-1500mi.

Well it is the EHA, I took off the air filter housing and I can see fuel dripping off of the bottom of the EHA. Is there a gasket that needs to be replaced or does the whole EHA need to be replaced?

u have to replace the whole thing

You have a used one for sale? How much?

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