EHA valve M103
 

What are the symptoms of a failing EHA valve on a M103? I have a fuel smell coming from inside the engine compartment as well as hard starting, surging idle when cold and a slight unevenness at idle when hot. Is the valve hard to replace?

The EHA valve is located on the backside of the fuel distributor. You will need to remove the air cleaner to see it. If you stick your head in there and smell gasoline in the area of the EHA, it's most likely the culprit for the gas smell at least. You may have some other issues which might not be cured by swapping out the EHA. One step at a time!

the EHA has two o ring seals that can leak. the other item to check would be ICV and its pipes. A thorough cleaning of the ICV valve and the Air intake plate ,to the throttle plate at the bottom will give you a good base to check everything if this does not rectify the fault.

You may have some other issues which might not be cured by swapping out the EHA. One step at a time!

What other things can I check? So far all six injectors+seals have been replaced as well as the fuel pressure regulator and accumulator. I put a set of Beru wires in and a new set of Bosch plugs except the dealer gave me HR9DCs instead of H9DCOs. I suppose I should try to swap them for some non resistor plugs but I don't know what will work. I can't find H9DC0s anywhere. Something tells me this is more of a fuel issue anyway. It seems hard to get a M103 to run smoothly!

MB specs non-resistor plugs for the M103 engine and there are lots of posts here and elsewhere about not using resistor plugs. Don't know why a dealer would install resistor plugs, but I personally would return the resistor plugs. I've heard that US dealers can still supply the correct H9DC0. I've also heard that as recently as last month, Phil at Peach Parts had them in stock. As an alternative, lots of guys like the NGK BP5EFS plugs, also non-resistor. I've used NGK in my M103 for quite a while with very satisfactory results. MB Classic Center in Irvine can source those for you.

Sorry your 103 is misbehaving after all you've put into it, but I can't agree that it's a hard motor to get running good. Mine now has 200K miles, and the idle is so smooth I have to look at the tach to make sure it's still running. Mine still has original accumulator, fuel pressure regulator, IACV and vacuum lines, CPS and temp sensor. EHA and fuel distributor were replaced 21 years ago under warranty, so you might as well say they're the original ones, too.

I've finally had the time to inspect the car and the EHA is in fact leaking. When I replace it, do I need to make any adjustments? Also, what things can I clean or check with the intake and fuel distributor exposed? Where is the IAC located?

Prepare for sticker shock on the EHA. Occasionally you see one for sale on eBay or other places, but they are used and subject to being bad also.
Might try changng the o-rings first, who knows.
The idle control valve is on the passenger side of the fuel distributor. It sits by itself in a rubber sleeve/holder. Has two rubber hoses about 3/4 inch diameter going to it. Looks kinda like a juice can. Don't know best way to clean it, but I used spray carb cleaner, the followed up with light oil.
The hoses on the IAC can harden and leak, definitely causing idle problems. They are pretty difficult to replace without removing the whole fuel distributor. We've done it, but it takes patience and dexterity.

DG

Front center of the motor.

every eha that leaks that I'VE replaced is because it leaks through the pins where the harness plugs onto it. not seen 1 yet where changing the orings where it bolts onto the fuel dist will fix it. good luck, chuck.

My M103 idles rough too. I recently replaced the O2 sensor at the recommended 60K miles and it idles worse than before.

Hi all!

Sorry to unearth an old thread, figured its better than starting a new one on the same thing.

Just picked up a '92 300TE. Low miles (sub 150K miles) and a beautiful example. Got it for a steal because it runs like crap!

Same exact issues as the original poster, smells of fuel in the engine bay, slightly hard start and a huge flat spot when you try and depress the accelerator.

I will check once again, but I did not notice any fuel leaking from the EHA, or anywhere around the fuel distributor. I will note that the fuel smell is very strong coming from the driver side fender area, so I'm thinking it's either the purge valve or the vapor charcoal canister itself is bad. Anyone suggest replacing these first, or dont bother wasting my time, go for the EHA valve?

Thanks all!

Check the purge valve . Remove it and put 8 volts to it , it should click on and off There is a check you can do on the purge system,.But i dont know it off hand ..

Purge valve port is so small it won't make noticeable affect even if it is wide open or plugged closed. The port in the throttle body is apparently above the throttle blade at idle, cause it pulls no vacuum at all at idle, then begins to pull a small amount as engine is revved a bit. my solenoid stuck open years ago, and I haven't bothered to replace it. So, probably not your problem.
Of course, if the purge is plugged up, you're gonna have possible problems with the cannister and fuel tank. Just to eliminate it, pull the line from the left fender purge solenoid to the throttle body, put a finger over it at idle and at 1500 and see What happens:
- idle, no vacuum on the removed line, no click from the solenoid on the fender
- 1500, a small amount of vacuum, and the solenoid will click if the engine is warmed up.

Best way to begin trouble-shoot for fuel is to check the EHA duty cycle, and see if the system adding or pulling fuel out (rich/lean).
All you need is a digital volt meter with a duty cycle capability and a bit of reading herein to see how it works.

DG

I went ahead and replaced the cap, rotor, plug wires and spark plugs as those were on order. Last owner apparently didn't take great care here as the old parts were no name aftermarket components with NGK R plugs gapped at .45

The small tune up here helped immensely, but she STILL idles a bit rough and has a flat spot when you punch the gas. You'll even get a sweet POP too!

I have a video. Yet to check the EHA Duty cycle. Noticed the hoses at the ICV are brittle and cracked. Could that attribute as well. Buddy mentioned my fuel distributor may be going out :(

I will add the video once I get to a desktop. Thanks again all!!!

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**EDIT FOR VIDEO LINK** https://www.youtube.com/watch?v=6YaRJF7C8dc

loud pop might have something to do with throttle body.