OK...I adjusted the EHA valve on my w124 a quarter turn CW to alleviate the long crank starting issue. It did work and started easier but it had to chug, chug, chug and then I had to give it gas and warm it up for a while. I figured this was not a good sign so I adjusted it 1/8th turn back. Now, it's back to a long first crank but when it starts it's idling better until it gets over 90 Degrees (everything is fine from about 82 to 89 degrees) and then it struggles a bit while in gear. Adjusted air mixture to best setting I could get. It's ok but not great. Anyone know why this happens and what part the EHA plays in the fuel delivery while idling? I've changed every sensor except for the air intake and since it acts up when the thermostat gets over 90 I figured this could possibly impact the idle with it's signals. Of course, when she runs down the road, there is no problem. Also, today, I took off and cleaned out the idle control valve and it looked pretty clean as it was and worked when I tested it with ignition turned on. Have new O2, non resistant plugs, new cap, rotor, coil, water temp sensor, and OVP.

Adjusting the EHA requires a CIS pressure gage to monitor the lower pressure change . Did you re-adjust the duty cycle after the EHA 1/8 adjustment?
mak

Yes. But I'm doing it by feel which I know is not good. I don't understand how to measure it. All I have is a Volt Meter...

Change the air intake sensor. I say this because:

a. It only costs €12 from Mercedes.

b. It takes 45 seconds to install.

c. In my case, it resulted in an almost complete solution to hot idling issues.

Either that or measure its resistance at various temperatures to ensure it conforms to specification. If not, splash out that €12.

Again, in my case, the duty cycle shot up from 50% +- to around 92 when the new air temperature sensor was installed. I adjusted it back to 50% +-.

Good luck to you.

RayH

Will order one today and let you know what happens! Thanks.

Steve

SPTT, the EHA is apparantly a pretty strange animal, after reading years of coments about it here. But, to understand it a bit better, I would recommend 3 things:
1. Pull down copies of some of the master techs' articles from the archives herein on adjusting and monitoring the CIS system. I think Steve Brotherton wrote a great one.
2. Buy a little $30 Sears multimeter (#82139 or similar) that has current reading capabiity and duty cycle capability. Read the instructions carefully.
3. Build a simple little 2-wire harness to interface the meter into the EHA circuit, so you can check the current during start and run.
4. Use the duty cycle meter in pins 2 & 3 of the round diagnostic connector on the fender well to check the idle lamda numbers.

These two bits of info will help you really understand what the system is doing, and when.

Then, if you want to verify, as stated above, you may need to get a pressure gauge set for the upper/lower chamber pressure. I found one on eBay a few years back for under $30.

Of course (the disclaimer) I've played with all these toys for years trying to remedy my heat soak starting problem to no avail.

DG

It's very satisfying when a cheap fix yields a big result. Do be sure to let us know!

RayH

[Q

TI've played with all these toys for years trying to remedy my heat soak starting problem to no avail.

DG[/QUOTE]

i am very satisfied with the exhaust heat wrap installed on my 300se. The under hood temperature dropped dramatically and better cooling inside .
mak

Well guys, I played with the Lambda and richened it up last night. Starts on first crank. Doesn't idle well 'til warmed up to around 76-80 Degrees then everything is fine. Acceleration from stop/idle was strong, ran well in 100+ degree weather for 90 miles to work and back. Started up fine every time. I guess I compensated enough for it but will it pass smog if needed???...probably not I'll check the duty cycle thing when I get a chance to get one of those meters. Will be good to learn and I'm very familiar with electronics and repairing and testing them...but you have to have the right equipment to test! I know someone's been in that fuel distribution system before but it did pass smog when I bought it.

its funny you mention the eha,ive been having the same issues with mine,i replaced the old one with a used one off ebay,had the air fuel ration recalibrated,i found the engine runs like crap boggs ,loss of power,pops in plenum,needs to warm up to operating temp.then when i disconnect the eha,the car runs strong has lots of power,does not hesitate does not pop in plenum,but when it sits for about 30-40 mins its extremely hard to start,i assume cuz disconnecting the eha leans out the fuel mix.well the weather is getting colder now,so i may plug it back in and see how it runs in the winter.but it also needs an o2 sensor,i wonder if the 2 work in unisome with one another?

Interesting. I haven't tried unplugging the EHA yet. If I don't get it to turn over on the first crank, I have to crank and give it gas until it finally starts. I wonder what the heck the issue is? It seems so simple. One of the guys mentioned the fuel accumulator could be the culprit ($109.00 part) as the diaphragm inside fails and pressure is lost to the fuel delivery system. But when I disconnect my EHA, fuel squirts pretty hard everywhere. Anyone know if that is an indicator of a good accumulator or not? Car was hard to start again today but it was 110 degrees outside. Ran fine once engaged and moving but idle struggled, yet, once again

A quick and dirty check of the accumulator would be to let the car sit a couple hours, then loosen the incoming fuel line at the fuel distributor. Then if fuel sprays out, you can be pretty certain the accumulator and fuel punp check valve are holding reasonable pressure. I did this last week; attached a gauge to the incoming fuel line, and hit the pump to bring pressure up to 78. After about an hour, pressure was still at 63, and at 30 overnight.

DG

Ok....I did the fuel pressure check and it has plenty, even after 6 hours of sitting. I can hear the fuel pump buzzing fine also. I guess something happens once you put these old girls in gear that causes the idle to struggle against that torque converter load. Lack of vacuum pressure? Air leaks or something that have to be perfectly tight? Leaky valves? Poor compression? I guess it could be anything. But when I go, that thing hauls as good as I think it can. Changed the Air Temp sensor today with a new Bosch part...same issue And, it just seems to be the heat. This morning, it cranked over fine, idled under load and no problems. This afternoon, hot...struggling and stalling!!! Arghh!!!!

Sorry about the intake air temperature sensor.

What is the state of your distributor rotor arm? Many hot running issues can be down to the suppression resistor going hi-res in the heat.

I would now read the codes from the MSG (engine ECU) and see if anyhting comes to light.

RayH

Well, I don't have anything to check with that I know of but the rotor arm is brand new, I was thinking about getting new Bosch Copper Plus plugs and trying those. I checked the cap and ity looks brand new with little wear although it could be broken down internally....something tells me it's not though...it's meant not to be solved so this forum can keep going forever