EHA rubber O rings hard start cause? - PeachParts Mercedes-Benz Forum

sptt · #1 10-21-2010, 11:28 PM

Could the little rubber o rings between the fuel distributor and EHA valve cause a slow pressure leak that might cause the hard start issues everyone is experiencing? I have heard of people replacing the whole thing but has anyone just tried replacing the o rings to see what would happen? I think I will since not much is left to replace and I still have hard starts cold and warm.

ps2cho · #2 10-22-2010, 01:12 AM

No, it will just leak and you will see a film of fuel all over the EHA. Run the car and just watch. If no bubbling or film then you are fine.

Hard starts can be the temperature sensor on the head. Check resistance between the two pins. It should be ~3000 ohms cold, ~250 ohms warm. Also if you unplug it while the car is cold in the morning and the car is much harder to start, then you can assume the sensor is OK.

mbzman · #3 10-22-2010, 01:51 AM

From what I've read 9 times out of 10 the valve is defective. I just replaced mine this year and my car only has 70k miles. They do seem to get old with age and crack causing fuel to leak. Pretty easy to spot if it is leaking.

ps2cho · #4 10-22-2010, 02:44 AM

Quote:

Originally Posted by mbzman

From what I've read 9 times out of 10 the valve is defective. I just replaced mine this year and my car only has 70k miles. They do seem to get old with age and crack causing fuel to leak. Pretty easy to spot if it is leaking.

If it is leaking between the distrib and the EHA it is just the O-rings....any leaks out the rear-side means it is toast.

In my experience though the EHA has a huge influence in power, starting, MPG...everything.

My wagon for example -- Original EHA -> 13mpg Perfect fuel pressure... I swapped it out with a junkyard. Same fuel pressure, 17mpg. No change in driving patterns. Tested over 10+ fill ups. Makes no sense...but the hydroelectronic valve can wear or get gummed up I would guess.

When I bought my 260E...failed smog horribly, would bog down as soon as you accelerated hard then clear up over 3k rpm....Fuel pressures dead on. Swapped it out, completely different car. Just bought a new one last week and it starts much nicer and idles a little smoother. Still chasing down my poor fuel economy though. I'll get to the bottom of it.

It is a shame they are over $220...so its really a crapshoot since you cannot 100% say it is bad, or 100% say the one you got at the junkyard or on ebay is 100% GOOD.

rayhennig · #5 10-22-2010, 06:26 AM

Quote:

Originally Posted by ps2cho

If it is leaking between the distrib and the EHA it is just the O-rings....any leaks out the rear-side means it is toast.

Mine appeared to be leaking from the joint between the EHA and fuel distributor. Changed the O-rings - no change. It was the EHA itself and it was changed for one from an older car. Much improved.

RayH

Ferdman · #6 10-22-2010, 08:46 AM

sptt, you might want to talk to an indepenent tech and see if he is able to check the setting on your EHA valve. It may only need an adjustment.

sptt · #7 10-22-2010, 11:21 PM

Wow. I know these things are too expensive for what they seem to do. I do not see any leaking around the EHA. My car is a '91 300E. My Daughter's is an 87 300E. Maybe the earlier parts were built better? I can swap it out with hers and see what happens. Also, a while back I adjusted it clockwise and it seemed to help the starts but I adjusted it back a little for some reason. Maybe it's just out of adjustment now? I read somewhere that depending on the car, these are adjusted counter clockwise either 5 1/2 turns from closed or 6 1/2 turns from closed. Anyone hear of this before? Can these units actually be tested locally? I currently am getting +20mpg highway with new injectors.

ps2cho · #8 10-23-2010, 12:21 AM

Oh that is perfect. Swap the two EHA's. If your daughters starts fine, swap the two. See if it replicates the same on her car. It is not fool-proof since mixtures will be temporarily changed, but it may do the trick.

sptt · #9 10-31-2010, 08:50 PM

....OK, I ordered a new EHA Valve. We'll see what happens when it gets here. Today, I changed my oil and filter and decided to check for vacuum leaks using starter fluid on all hoses and connections. The only variance I had was when I sprayed it into the air mixture plate and adjustment hole. Nothing from IACV valve hoses or injectors/injector areas. Was wondering if coolant leaking into engine block could also cause the hard starts? It has been cool here and does the chug a chug thing until warm, then perfect. Acceleration and idle great! A little white smoke in the morning for about 5 min...losing coolant but oil is perfect and not milky.

sptt · #10 11-03-2010, 09:39 PM

Hello everyone. I just received my new EHA valve today and installed it on my 300E. The first thing noticed was the car started up faster but idled a little rougher. I figured the computer needed to get use to it so I did not worry. I moved the car about 1000ft turned it off. Went back to it about 30 min later and turned the key...again it started a little better and stronger than it did before on first crank. I drove it around for about 5 miles and it definitley evened out on idle. It did struggle on acceleration from stop and when cruising around to pedal down. When I got back home, I took out my trusty new Sears Multi Meter with Duty cycle ($29.99) and hooked it up. It was definitely off. I adjusted the duty cycle per the link provided in this forum (richer...1/8th turns) and got it within the 50% range. Took it out and acceleration was back on track. It was 100 degrees plus out here today so I was very happy with first key turn hot starts. Will have to see what happens in the morning after cool down. Before, hot starts were not consistent even at cooler temps.

ps2cho · #11 11-03-2010, 10:11 PM

Fast starts is exactly what I have experienced too. Great to know that both of us have experienced the same thing. It is obvious then that the EHA has a lot to do with regulating fuel during both hot and cold starts.

Rock on!

sptt · #12 11-05-2010, 01:59 AM

Good news! For the first time since I have owned this car in over a year, it has started on first crank, cold in the morning, hot during the day, and cooled off at night...first crank! Getting the new EHA Valve (after replacing fuel injectors and seals, plugs, plug wires, cap, coil, rotor, both pumps, fuel filter, adjusting the lambda with duty meter, and a new accumulator to throw parts at it recommended by the forum...which I'm sure I would eventually need anyway) the car actually seems to puurrr when driving now and idle is, well, what idle? I can barely tell the car is on! It's gotta be as close to feeling new as possible and I LIKE IT!!! Only thing I wish I could easily get now are more comfortable seats. They're not designed for cornering while holding you in them at the same time! Go for the EHA Valve first before the generic OVP answer. I got a new OVP and it didn't change a thing so I pulled it and am saving it by using the old one. All of the other things helped my idle but nothing helped the starting until this.