Wow, this is weird, I am getting 74.5 mA.... I've checked three times, this seems awfully lot. I did get a WIS manual, but its taking me a while to learn how to use it. I've retested it throughly. The fuel distributor is holding pressure very well, equal amount of fuel from all lines when plate depressed, the plate is holding pressure when closed.

Well, I have tested over and over and my results don't make sense. WIth the engine off, key on run, the current at at eha is 74.5mA, once started the current drops to around 9, then slowly drops to 5mA. When I blip the throttle when the car is running, there is a drop to between 1-1.5mA I have repeated these tests numeroust times, with engine cold. I also replaced the overload protection relay, and now have the check engine light on (this could of been caused by the action of replacing the relay as the manual states) This being a california car, I am able to read off the codes, I get 9 blinks on the led, I have not looked them up jet.

Yes these EHA currents do look wierd atleast for my 87, 260E and a lot of other W124 models. Is it possible that they are different for your model ? Though I dont understand why the EHA current does not change dramatically (i.e > 15 ma or so) when you blip the accelerator. That defeats the whole purpose of the EHA. As you must have already noticed, the car will run without the EHA because the mechanical fuel injection system is adequate for that purpose, but during acceleration, the extra fuel is rapidly provided by the EHA. It is not required to mantain a constant speed, the mechanical system (i.e. the throttle, air sensor and the fuel distributor) is good enough for that. The ECU is controlling the current thru the EHA, and it determines the current based on various sensor signals. Either one of the sensors (air flow sensor and coolant temp sensor are the most likely candidates) is bad or the problem is in the ECU. The fact that the current is so high just in the run position of the ignition switch makes the ECU a very likely possibility.

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Saumil S. Patel

I have dug some more through Mitchell, at my friends shop, the spacs for the EHA looh dead on, for a 1991 500sl. So I guess there is quite a bit of difference in the models.

I did more probing around, and I found that #1 injector is not getting any fuel in. Funny, when I started this, all of them were getting fuel, including #1. I checked the fuel distrubutor and nothing is coming out of there as well at #1. I guess were back to the distributor, I just can't figure out how an 8 cylinder engine would not start on 7 cylinders...

Is it possible that fuel is metered before this happens, so the end result is more fuel to the remaining 7 injectors, resulting in the overfueling? I'm really starting to dislike this Bosh solution, reminds me of the old Lucas injection problems....

Back to what David was suspecting from the very beginning, unequal fuel to different cylinders. If you dont get any fuel on one of the outputs of the fuel distributor, there is no other possibility.

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Saumil S. Patel

Thanks guys for all your hints and time, I've learned a lot through this forum. With all these issues, this is still the most enjoyable car to drive and own, hopefully when I get the whole thing up to snuff it will return the favor.