Another update EHA
 

Happy thanks giving to all, Well it is the day after and I took the car out on a test drive,Started up fine warmed up and played with the fuel mixture up and down slowly to find a place that seamed smooth and idled well.
Took the car out for a ride it did well smooth acceleration and shifts,about 10 miles,came to stop sign OK,on take off it had a shutter and I heard the fuel pumps running and it shuttered again then stalled,restart was Immediate,it drove for a short distance and I drove it into a stop and go situation,this was the telling,it would run rough and stall again I could here the pumps kick on.
I unplugged the EHA and seemed to do better but it was not,re attached the EHA it did not stall as in the first test.next I unplugged the green wire (ox)
and again I thought it was better it took off no problem,but a short drive into it and the car began to loose power and stall again I could here the fuel pumps,I have changed the fuel relay and MB changed the fuel pumps,we know the fuel pickup screen in the tank is new,I think I need to find more to look at now,at least we can now go out and start the car and check things.
Let me know what you all think j-n-t:behead:

more test's
 

Today I spent most of the day looking at the Idle of our 420,I kept looking for that pesky Vacuum leek.
Tomorrow I will work on the vacuum line from Engine to the break booster,just to see if it makes any difference in the Idle,and I also have the Idle control valve in the degreaser to see if that will help.
Test was run on the throttle position switch and it checked ok at both ends.
Break booster test was suspect, I stepped on the peddle slowly and could see the boost gauge move to about the quarter mark on the gauge and the Engine ran rougher and stumbled as if to stall,so we may be looking at more leeks in the break booster or some of the under dash components door locks so on. j-n-t:silly:

Idle control valve
 

Another test on our 420 sel,today I spent most of the day looking into the cleaning of and testing of the Icv,I found that with key on I had a pulse of 25 to 50 millivolts,I cleaned all dirt and grease from the valve,after replacing it and starting the car it would run up as it got its cold start shot of fuel and then would Idle down and stall,rpm would go to 700 then 500 and stall.Keeping you foot on the throttle at 1200 to 1500 and it ran till warmed after that it Idled but roughly. My next question is what should the reading be at the ICV,and what should the reading be at the plug wires.how many ohms should they read.
Vacuum lines,I plugged the main line from manifold to break booster made no diff.in the running of the engine. Well thanks for any help J-N-T:silly:

Plug wires
 

Testing wires today, I found #5,#8 not reading any ohms,while others are reading 3ohms.
rigged up some wires off a ford that I had lying around and the car ran a little smoother,so the next step will be all new wires.
I am still not getting the Idle I am looking for,it will not hold any rpm at cold start,It runs up as it should with the fuel shot from the cold start valve,but as it burns it off the engine stalls,some of it may be from the bad plug wires,we will know more after they are replaced.
New developments will be posted as I go along,Again thanks for all the help from all who have put there two cents in.j-n-t:silly:

Ok gang, I have completed the task of repairing the vacuum leaks and replaced the wiring(plugs).
Was having an Issue with cold start, It would fire up and search for balance and stall.I fattened up the fuel in small increments Until it held the idle. Cold idle on start up is 1000 rpm then balances to 700 rpm.holds that threw out the warm up and warmed condition.
Test drive I had a slight hesitation on acceleration, I added a little more fuel and it cured the problem.
Now we are looking at a stall problem, after it is warm and has gone quite a long time it acts like(if it had a carburetor the choke slams shut) it starved for fuel or was in a flood condition,like it is choking the vacuum gauge goes to the max. Any more thoughts?

Cool job JNT, Nice engin to work on right? Not an old hand like Dave on these, only took apart one 380. I think the varnish would not be there if the air leak hadn't been there. How did you get it down to 700? hows your timing?

Tomorrow I'll check the icv voltage for you. Put a timing lite on it and tell us what you see at 700. Then pull the vacuum hose on the EZL and see where the timing goes. I've ignorently played with the mix on my old 380, with my 560 it makes more sense to me now, but it sounds like your mix is about right. What voltage do you get at pin 3 on the X11 round diagnostic port? Mine is about .4VAC I think typically .4 to .6.

By the way "starved for fuel" is not enough gas - plenty of air, and "choking" is plenty of gas - no air, opposites. Pulling the plug on the icv opens the air passage, mine raced so I knew it was too rich. Fun stuff, I lov these cars.

Rpm
 

I have no idea how it got to the 700 I guess the idle control valve took care of that though I did have all the linkage off and started FROM DEAD CLOSED TO just off the stop and brought all the other linkage to meet that position,As I said when I first put the system together the only rpm it knew was 4000.
Varnish is something else though I am sure it had a lot to do with wild adjustments in the linkage and the air leek (vacuum) j-n-t:silly:

FUEL more or less
 

Yes I was quite confused by it all, seems as though I do that to myself when I am not perfectly sure what is happening. The fuel problem was not completely clear to me,one moment it seemed as though it was starving and the next flooded.:dizzy2:

Garymand, the timing after warmed was at 12* after vacuum unplugged it fell to 5*
Pin 3 reading was 4 to 5 pulsing as the ox or the Eng. was looking for balance still not sure how to fully explain the problem, though today it ran at a rougher idle than yesterday.j-n-t

Sorry for all this detail, but it is a complicated system. I stopped at 11 points til you catch up.

1)I think you are saying the throttle valve is a little open. You said: "I did have all the linkage off and started FROM DEAD CLOSED TO just off the stop and brought all the other linkage to meet that position," and "when I first put the system together the only rpm it knew was 4000."

1)It should be DEAD CLOSED. Its not a carborator. The computer controls all the air at idle. And, the 4000 happened once you fixed all the vacuum leaks because someone used the throttle to compensate for the leaks. I can'r explain how it does that. But now you should have the dash vacuum gauge pegged on economy. Really good vacuum. The engine had a lot of air coming in and good vacuum and that pulled the gas plate down raising the engine speed beyond where the idle system could control it.

The screw on the throttle butterfly is there only to prevent the butterfly from sticking into the aluminum throat. It should be totally closed and even bit just a little. Benz fuel injection has always been that way.

2)ALL the idle air needs to be controlled by the icv. Except for the little bit coming through the bypass tube in the rubber fittings at the input and output of the icv.

3)When you adjust the mix too lean with the allen screw, the vacuum will pull the big air plate down a little and you will hear the sound of air flow increasing past the plate. You should try find that point with the allen screw and back off from there to 700 to 750rpm, air is not noticably coming through the plate, smooth idle, no hunting.

4)Remember that the O2 sensor output changes with exhaust temp and sitting at idle and playing with the mix allows the exhaust to be cooler than real driving. In fact when cold starting (with the sensor cold) the computer opens the icv to give an idle of about 1000rpm, (everything else set about right) until the signal gets into range from the O2.

5) To find the not-too-lean point, turn the allen screw CCW 1/8 turn at a time until you find it. You have to wait for the O2 sensor/computer to catch up and stabalize with the engine. Idle should stabalize in just a few seconds. I think it gets worse taking longer, as you get too lean leading to hunting. Once hunting lean, go back 1/8 at a time, waiting for the computer to stablize. Until you get 700 to 750, air is not noticably coming through the plate and no servoing.

It sounds like you know how to do this and are very close if not too lean already. Check it, drive it, heat it up, stop and put it neutral or park, if it hunts, pull over and quickly try 1/8 turns CW.

6) I can't tell you how rich to go. You want to be far enough away from hunting lean enough to save fuel and have good emissions. Hopefully someone else here has experience of where to leave it before you check the emissions. The mix adjustment will repeat well (the allen will be in the same position each time) and all within only one turn of the allen: go too rich, the idle goes above 800, too low and the idle drops to 600.

7) 600 seems to be a computer limit, once there the hunting gets worse, but rpms won't go lower. I think this adjustment should be set so the idle is about 700 to 750, air is not noticably coming through the plate and no servoing. When you get too lean with the allen, go back 1/8 at a time until the idle is stable: no stumbling sound in the exhaust, no sound of harsh sucking through the air plate, rpm 700 to 750.

8)The hunting is due to the O2 sensor and computer changing the air too far and then changing it the other way too far. The system tries to self-adjust (hunts) to try to keep the engine from stalling or idleing too high. I'm not sure, but I don't think the gas is servoed at idle. I think its just the air flow through icv that is under computer control. The icv is big enough to control all the idle air the engine needs.

Its normal for the O2 system to look around a little for the best setting and older engines never have a perfect best setting, the .4 volts at pin 3 X11, will move around +-.05V as the O2 sensor roams around making sure its keeping the air about right for the gas flow.

9) The .4 volts moves around as the O2 sensor/computer adjusts the fuel ratio with the icv. The voltage at the icv is the result, adjusting the air in this 'closed loop' idle system. The input is the O2 sensor.

10) My vacuum at the EZL does the same as yours. There is a "dongle, (computer term)" R16. Its a plastic plug connector with no wires coming out of it back next to the brake booster. It controls the 5* setting with vac off. The normal value of R16 is 750 ohms.

11)I'm unclear what the vac-off timing should be, I don't have the manual for this car. But vac-on timing has to do with idle speed, mine was up at 30* with 950 rpm idle and 12* at 700 rpm.

11 and more to come!
 

Garymand,first yes,the lower plate I set just off the stop I thought I read some place that it was to be set at 1000 thnd mm off bottom ofcourse that may be what it should be at the stop too.
Carb type intake leeks or cracks you can over compensate by increasing the idle mix this must have bean what they attempted to do with th linkage,because when I dropped the links off the balls I was able to get off the screaming 4000rpm to a 750 or 800,then I pulled the plate off stop.So what you are saying is get back in and reset the plate to its stop and readjust more in the fuel till I find that place where it dose not hunt!:book:

OK, I went out to the shop and took another look at things and reset the throttle body to its stop position, then began to lean out till I could here that rush of air over the horn, at that point I added fuel in 1/8th turns till it began to smooth and finely it stopped searching.Now if it will stay things are going in the correct direction! Yes I know I am a nut to put so much time into the car but it is such a fine car I hate to see it go all to h--l.

JNT I'm learning too, just got my CD manual and can't get the manual to "start," have to look at each group of pages individually. Life, if it's not one challenge its another.

I've had some strange things happen. Probably because I'm a newbie to troubleshooting a 126. First times I pushed the button on the X92 with the engine off or on nothing happened right. And I didn't know I had to push the button to get the ratio on X11,3. I had to push the X92 button with the engine running!!!! and the led flashes: one flash = everything OK. press again and NOW!!!!! you can measure % ratio at pin 3 of X11.

Someone said you turn the key on but don't start the engine, that didn't work at first. Now it does!! Others have talked about the measurement but didn't explain you measure 13.xVDC normally at x11,3 and you can't measure the ratio until you do the X92 button pushing. Critical missing info. And I found by trial and error use the DC scale, not the AC scale and a dwell meter measures it nicely. (since the voltage is changing, it is AC but you won't get the same values)

JNT, do you have a dwell meter or a scope? if so let me explain what no one else has: Connect the - to ground or pin 2 and + to pin 3 of X11. Start the engine. Normally you will read charging voltage 13.5 to 14 volts. The dwell meter would drop to zero. Not very helpful.

Now find X92 back by the battery between the two firewalls. Flip up the plastic lid and see a button, a clear plastic covered red led and a number of pins.

Strange newbie stuff: the first few times I tried to do this it didn't work right. With THE ENGINE RUNNING, press the button for 2-4 seconds. If you should see the led blink once GREAT. It means no error codes are stored. Lets go with that. Now press the button again for 2-4 seconds and the led stays on. (Check your Engine Warning lite. Mine came on and goes off once you restart the engine. The manual says it should not come on, maybe a translation problem in the manual).

NOW you will see the %ratio at pin 3 of X11. the voltage and /or scope pattern.

Adjustment is a little tricky, I went lean first and then backed up. I think you are on the lean side too. On the dwell meter you should see a dwell about mid scale or more to the right, like 60 70%. Look for a 50. And /or a about a 50% square wave. I had both a meter and a scope on and watched both, found the meter needle movement more helpful.

Here's the tricky part, the manual says you want <10% difference between the hunting at idle and the hunting at 2500rpm.

The voltage for me was about 5.5 V and moving around about a 1/2 volt. So the needle was swinging between 5 and 6.

(I should mention vacuum advance: I'm not sure what colors go to the EZL, but I switch the one to the purge valve and got much better idle results and this allowed me to pass smog. The plasic line I'm using has no vacuum at idle. The other has vac at idle and pulls my idle up to 950 and timing to 15 to 30. This fails smog.)

**When you are far off, the voltage drifts in one direction and suddenly swings back then starts to ramp again. I found on the lean side the voltage rose slowly way up to 8, and jumped back low to 1, then started rising again. I had to slowly go richer until the wave was square and the needle was hunting between 5 and 6 volts. The closer you are to matching air for the gas supplied by the current at the gas distributor (0ma?) through the injectors, the slower and more restricted the meter movement (searching). I haven't measure the current yet. The icv current is 700 to 900 on mine meaning the valve is closing off the air to keep the idle down.

The objective is to adjust the 3mm Allen to where the voltage is near 5 volts DC and ranges about a volt randomly, but not to abruptly, avoid the wide slow movements that sudden shift back indicating the adjustment is too far off center.

I found a place about 6V where the drifting was +-.5 volt, but 2.5k it was at 3.0. I went a little richer to 5.5V and the 2.5k upped to 4.0 +- .2. I went a little richer to 5V and the 2.5k came in very close to 5V. I think you have yours in about the same place. (The voltage freezes for a few seconds, I thing stabalizing before servoing again.)

I found, if the 2.5k place is to the left of the idle point you are too lean, turn the 3mm CW maybe a 1/8th turn, look at the needle range and compare to 2.5k again. I played with this for 3 hours. I tried going too rich and trying this on the rich side. Working my way a 1/2 turn either side of optimal. The sweet spot was all within 1/4 turn to get the <10%.

Unfortunately this hasn't fixed my high idle problem my idle at the optimal point was closer to 900 than 750. So to pass smog I had to go leaner to get the idle down to 800 and timing down to about 14 with vacuum. That is when I tried the other closeby vacuum line attached to my purge valve. That got the idle down to 750 and timing to the R16 setting of 5*.

Today, Xmas, I found the diagnostic X92 button is working now with ign on and engine off !!! I get all the right ratio voltages for a CAL car, found the idle switch does not effecting the ratio until you press down the air plate!!. Wierd you have to read so many places in the manual to find the right how to.

Il tracked down all the signals tha control idle (except grounding pin5 on the idle control unit and duplicated the optimal place to meet idle/timing and smog. And my O2 sniffer says I should pass smog. I'll also read about adjusting the pressure in the gas distributor and see if the gas supply pressure is right.

By the way, we are all nuts to put this much time into a car, but then I think about how PO'd I get when I bring a MB to a mechanic and he doesn't have a clue.

I know none of you are this way, but when I first started making $$, I brought my 250SL into the dealer for a king pin and lower A frame bushings: Next day I drove up the mountains to ski, 6 hours RT. When I got back the front end didn't feel right. Looking under it I found one bolt missing and three bolts very loose. All the bolts holding the lower a-frame to the sub chassis were very loose -about to loose the nuts. And air chisel marks were around the bushing areas of the A frame. He used an air chisel and couldn't keep it steddy getting the bushings out!!

I took it back and got an explanation that new guys have to work on something... I haven't taken a Benz to a dealer since. I'd rather learn how to care for these beauties and not have the disappointment.

My wife and I took the car for the first long trip on the 23rd, the only thing I find is that I have a hesitation when cold say below 40c, once it is at 80c it is a well balanced machine. To try to fix the cold take off I added fuel, But after the car sat as we ate,it would not start unless I held my foot to the floor, So I reset the fuel, Starts fine revs to 1000, then drops to 800 and now will idle at 600.If I try to get it up it goes to rich.I may have to try another Icv, but for now I am pretty happy that we can enjoy the car and make it back home. I need to call Dave and get with him for a meet and great I just have to confirm the dates I will have to be in Dallas for an MIA meeting Well its also KIA too. I will know more in a week or so. any who just wished to say Seasons greetings hope all are well and safe J-N-T