M103 Leaky EHA, Lost power
 

The car is a 1991 190E 2.6L M103 5 speed with almost 350,000 miles on it. It's been having problems rough ideling and running at half power when warm. It goes into this mode the instant it thinks it's warm enough, it runs fine when cold. I've changed the fuel filter and distributor cap (rotor is in good shape). I've noticed the EHS drips gas and have replaced the green O rings and glued parts of it, including the two weep holes on the front. It is still damp with gas and still run's bad.

I've heard of the "limp home mode". Could that be what the car is doing?

I'm wondering if a small leak from the EHA could cause this problem.

Any suggestions? Should I keep glueing it?

If the EHA is leaking from anywhere but the o-rings, it's shot, you'll want to get a new one or source a good used one (I would just try ones from junkyards, I wouldn't pay much money for one). I'd bet it's at least part of your issue. Other thing I would recommend is pulling the OVP relay and reflowing all the solder joints.

I've found one for about $160, but that's more than I really wanted to put into the car.

I have another OVP relay, the older version, I could try, along with re-flowing the one that's in there now.

I agree, try the simple things first.

Jim, you definitely need to replace the EHA Valve once the body has cracked. Glue is not going to repair the leak, and the leaking gas could start an under-hood fire. New EHA Valves cost around $265 so I would buy a new one, instead of taking a chance on a used one for $160 that may develop the same problem in short order.

I don't believe CIS is complicated enough to have a "limp home mode"

There are, however, several ignition and fuel delivery schemes the ECU goes through during warm up but this depends on the age of the system (got more complicated towards the end of production).

The number #1 problem(s) with CIS seems to be vacuum leaks (so start taping up joints with self amalgamating tape if you want a low investment in your fixes) and fuel leaks.

It could be (I can't be 100% sure because the inner workings of the EHA are still a bit of a mystery to me) that the EHA is positioned differently when the ECU believes the engine is warm enough => in this position it leaks - fuel pressure drops (which is very important in CIS systems) and that's why the performance is bad.

Replace what you know is not good - replace the leaking EHA. Do a WTB ad - post up the ID numbers on your existing EHA as well. Someone on the forum must have a bit for you.

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Be prepared for a fair amount of fiddling about with that adjustment screw - so get a multimeter that can read duty cycle - for when you fit a different EHA

How about engine temp sensor .If its gone bad it will send message to ecu to make change in the fuel from rich to weak or vise versa .May be stuck in one position.

EHA- used works!
 

If you can find a seller that's close to you (same state), has a long warranty (months not just days), and has a good reputation (high and many positive feedback ratings), I wouldn't hesitate to purchase a used EHA on eBay for less than $75. It only takes a few minutes to install. They either leak or don't. Make sure you get a NEW set of real EHA o-rings with it. Do not re-use the old ones unless they are less than a year old. The new, improved material for them (I'm told, anti-Ethanol) is colored light green. The original ones are dark green. They are an odd size and can not be found at the local hardware store or auto a/c shop. Of course, they have them here at Pelican.

It's as good as dead now
 

This morning, tryed to start it and it barly started, ran really bad and never got over an idle. I didn't get a chance to do anything with it today, but noticed a fuel pump seemed to be making a little more noise that it used to. It was a little noisy when I replaced it about 50,000 miles ago so millage wise it should be ok. I think the end might be in sight for this car.

And I did check the temperature sensor, it's ok.

I know you don't want to spend the money, but at this point just get a new EHA. You should be very happy at getting 350k out of it. Used ones 90% of the time are bad, so you'll end up wasting your time and money...and even if you get lucky with one that runs, you can sometimes be plagued with other power issues -- diagnosing CIS-E just plain sucks.

One option you do have to at least get a better target is to do a fuel pump volume test. This way you eliminate everything other than distributor, eha and injectors. (assuming your ignition is OK and no vacuum leaks (those idle control hoses will cause a no-start condition if they are split, which usually you cant see))

Exactly. It leaks, replace the damned thing already.

I agree. Our '88 300SEL (3.0L I6) had a leak from the EHA valve and I bought one off of ebay for like $20.00 and it worked fine and it has for the last 4 years. The one for your model may be more $ however, not sure how differently those are set up, but IIRC it was super easy to change on ours.

Good luck!

Do not Glue!
 

Yes, all your symptoms are very likely EHA caused. I also just noticed that you wrote you "glued parts of it". Very bad idea. The weep holes are there to tell you that your EHA needs to be replaced. I urge you to not waste another minute and invest the less than $75 for a good, tested, used one with a long warranty, or swallow hard and get a new one for about $250. Either way, solve it first. Gluing the weep holes is like trying to glue the weep holes in a water pump. It will keep it from dripping for a little while only to leave you stranded later because the bearings failed and seized the pump causing even more unnecessary damage. All because you didn't heed the warning that the dripping was telling you about the need to replace the pump. If that EHA fails and causes the car to shut down at the worst time, the engine isn't the only thing that could die.

It was the OVP Relay
 

After my first run-in with engine problems and subsequent searching the internet I bought a OVP relay. It never fixed any of the problems so it got moved to the bottom of my list of things to try, but it was still on my list. I just changed in and it starts and runs like new!

I'll take it apart and see how it looks, and re-flow it and probably put it back in, it's the one with 2 fuses and the internet says it a better one.

Jim, glad to hear you resolved your problem.