vacuum leak update
 

just-n-time here,I got into the fuel tank filter today,it looked good,some trash but just enough to say it is doing its job.(see pic)
Intake is another story,it is a mess,the air duct housing was not properly seated to the intake must have leaked.
Varnish is abundant in the air duct,and nasty looking in the lower intake too.
I will keep every one informed as I go thru the system j-n-t:behead:

Dude, you must be really bored...

Great job. I hope to never have to do that.

bored who me?
 

Not even in the least! I just like things to work,If I cant go out and turn the key and go then I must know the reason why.Perhaps It will be for my own edification,or some thing to pass along.Besides I have to do something in my early retirement,j-n-t:behead:

Ok, I am going to admit my ignorance in the interest of learning something :) So those pictures are of the ducting from the airbox to the throttle body and they are coated in oil because there was a vaccum leak in the ducting that killed the vacuum which allowed oil from the EGR or something to enter back into the system due to a lack of vacuum? If true, did it kill your MAF? What model of car is this, please?

Thanks!

oil,No
 

First this is a 1990 420sel,The trash you are looking at is varnish,and soot from a very rich condition.I split the intake today and have more pics for all to see. The first shows soot,The second is badly varnished,third is cleaned The last is another view of the soot. all the o-rings are hard:behead:

product of years in storage
 

By the way I realize you haven't read the other sights in my name so just in case others have the same problem,I should say this car sat for a very long period and varnish got to it,It was repaired but only skimmed over and so much else needed to be also addressed,sense I got the car I have tried to put it back in the shape it should be in,j-n-t:behead:

So where is all the varnish comming from? Varnish is whats left after the gasoline evaporates. There should not be any fuel in that part of the intake system. I suspect that the fuel distributor must be leaking fuel into that area. If so then it might need to be replaced.

What are your thoughts on this?

make sure you replace every rubber part on and in this intake.including injector seals and cups and o rings.all the air tubes including the one going under the fuel injection plenum.you will be very pleasantly surprised when all back together.

David, If I call you-- Could you answer a couple questions I have about my 88 420 SEL?


Sorry to hijack the post-

Carry on-

fuel distributor
 

This is one part I know was replaced or rebuilt by the service department at my MB shop,just before I got the car I have had it for 10 months,and we only have put 250 miles on it,and have had a great deal of work to do in order to get it back up to snuff. though when I removed the intake it was wet in there I thought it might be from me trying to start it! Not real shure.j-n-t:silly

Hi Dave
 

Yes my Friend,I have all new donuts,inj.seals but I did not order cups or o-rings,I will call Phill friday morn. what do you think about the wet in side the chamber? think the fuel dist.block might still have a leek? It was very wet deep at the throttle body chamber. Well one step at a time, rather take baby steps till it is done. j-n-t:behead:

When I did mine, I found the EGR pipe blocked with soot at the intake manifold. Also, the pipe on the bottom of the air cleaner tha mates up with the hose to the back of the passenger sode valve cover was also blocked. Don't forget the clean the small orifice in the idle air bypass area and cold start injector. I had to use my trouble light probe, with a really sharp point, to push out the gunk.

Check the groove on the heads under the intake ports for carbon deposits.

I used a media blaster to clean my intake manifold both inside and out. It looks really great now, at least the parts that I can see.

carbon
 

Yes I inspected all of that and it was farely clean, the trac at the bottom of the heads had some build up but not pluged.It is just so cool that this unit has so little of it for as old as it is. Thank you for the heads up j-n-t:behead:

up date
 

Well today I got every thing put back together and after holding my foot to the floor it Finlay lit off,though it idled at 4000 rpm.Apparently it was adjusted in the throttle linkage to compensate for the air leek at the air duct housing.
Worked on that and have it at 700 now but I am sure we will have to continue to fine tune the system,as it is rough right now will work on it more in a couple days or so and continue the update j-n-t:behead:

varnish
 

The only thing I can say about the varnish is that whom ever re installed the air duct housing and did not get it seated on to the throttle body,a gap was to much for the fine adjustments to solve so the option was to open the throttle body linkage there by increasing the amount of fuel to compensate for the added air,this caused an environment to be in a flood condition,perhaps I am wrong but it is the best I can come up with,j-n-t::idea2:

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

Voltage swing
 

The trip was enjoyable We drove a couple hundred miles and it performed so very well, the only thing was a slight hesitation when cold. Today I worked in the Engine bay trying my hand at getting the voltage swing to stop its large swing, It is now set on the 10 volt ac setting and the reading is bottom 5 volts swinging to 8 volts, I had a constant 3 volt swing no matter how far I leaned the system or richened the system.
Checking the #3 pin on x11 IF I am doing something wrong can any one let me know? Oh yes I almost forgot Idle had fallen to 600 so I lengthened the long rod till I got 700 to 750,tomorrow I will see if it starts in the cold.:dizzy2:

Foot note the Eng. worked just fine after a cold start up, lengthening the long linkage rod bringing the rpm up to700 or 750 worked with out any problems,so far.
Hope every one has a safe and great new Year. j-n-t.

JNT, making progress, you got 600 idle and I passed smog and we've both learned a lot and still don't know what's right. "lengthening your rod" is a real trick, but I know exactly what you mean. Its agood way to get home but not right. DC voltage is right and a digital meter is not very usefull, a needle is helpful.
I found 2500 a good place to do the mix, get it to 50%. then check at idle. Just the opposite of the manual. This way I end up with closer to 50 at idle.
Also the vacuum is critical on mine: I found very poor results with vacuum on. The line to my EZL had no color stripes and vac all the time. The one to the purge valve has purple and black stripes and no vacuum at idle. I switched them and life is much easier. It passed smog with a 750 idle and 5* timing. I told the teck what I did and he said it must be right. I really don't think so. But the car passes.

You can check your system (and voltage readings) with X92, ign on but do not start engine. Led is on, voltage at pin 3 X11 is 70% 3.84 volts DC meaning USA non CAL, Fed, 85% is CALifornia. Open the throttle full, 20% says good full load switch, depress air flow plate: 10% is good idle switch. Important is the relativity of where these %'s are on your meter. The formula for volts is dc reading/pin 4 voltage (battery)~12.8. ie., 3.84/12.8=.30, 1-.30= .30x100=70% Fed controller. The voltage is higher with eng running maybe 6.4/13.8 would give you 50%

Voltage
 

Hello, I did not party to much,we had Friends from Texas in and did our thing a day early so they could get back home for the big party you know how Texans are.
On to the testing,I redid everything,and put it in the DC settings and got the following. pin#4 x11 12volts, pin#3 x11, 3.2volts after the formula I get 73% I think I am pretty close to the correct settings. All testing was done key on not running. I think that once I get the rpm thing fixed I will have to try another ICV we will be set up for some enjoyable cruising.j-n-t:laugh2:

Are you up to checking the ratio again? Can you get the ratio near 50% at 2500 rpm? On mine the idle % falls in very close just wider.

The current is easy to measure if your meter measures current. Some multimeters don't have a current capability. If so the meter leads go between either (but just one side) post and the corresponding socket. That is in series with one terminal. The other post and socket need to be jumpered (connected)

Try to re-explain that,you lost me!

OK but check this out too, Search on patrick_mb to see his two threads on M103 W126 part thottle mixture adjustment. He did a great job of explaining what to check and measure the mix. He also explains what you do with the EHA current.

He explains it a little differently and that helps me alot. He describes going too far rich and too far lean and watching the O2 sensor output while driving. I've watched the ratio but not the sensor.

What I was getting into was how to measure the current at the EHA. To do it your meter needs a current range and I just realized I have a clamping amp meter attachment for my cheap radio shack multimeter. The connector in on the gas distributor drivers side back corner. Black plastic thing with a two wire connector that pulls off towards the rear. With a clamp on, you don't need to rig up a way to get into the circuit to measure current.

Basically you open one of the two connections and the meter remakes the connection. I used some banana plug leads. Just find a way to connect one side with a jumper and connect your meter bewteen the other two. Choose 1Amp range first for the .75 A at Ignition switch on, then down range to see when you start the engine and want to see the +-.1A

I had to clean the gutters today (yes dear) so I didn't get a chance to duplicate what patrick-mb did.

73%
 

OK, I spent some time today trying to do the job on the % of on off ratio, Static gave me 3.2 and 12v. at pin 5 eaquals 73% to get closer to 70% I should fatten up the fuel is that the correct direction?

Ok I am back took another look at things,static ,I got 3.4, then 12volts, ok I pushed the plate down and got 9.4,when i released the plate I got 6.4 so by the way I also heard the plate scratch the horn as it came back up so I must have some work to do in the adjustment in that area,but how?I will or I suppose repairer so that it flows freely must happen be fore any other work can go on? I eagerly await the how to's. j-n-t

HI I am back, tried to set the fuel at 2500 my reading was 71% at idle and 85% at 2500 re set the fuel to get 10% dif. but it just would not take the fuel on acceleration, so I had to fatten up again. I dont know if I wish to try messing with the EHA settings.I do have a couple of fuel gauge that go up to600 pounds but I dont feel comfortable yet, maybe if I read more then I may attempt it.

You are making things too complicated or you dont really understand what you are doing. Setting these things is simple. It goes like this - Set your duty cycle at idle or at 2000 rpm. Your choice. Once it is set leave it alone. If the duty cycle varies a great deal between idle and 2000 - 2500 rpm then there is something else wrong. Things like - vacuum leak, fuel distributor, fuel pressure, EHA, airflow sensor pot and on and on. You can adjust the mixture till the cows come home nothing is going to change until you find the root cause of the problem. The ECU (engine control unit) is responsible for enriching the mixture when accelerating. It uses a signal from the air flow sensor pot. Yours is probably shot. Stop fooling with the mixture control and look for the problem in other areas. The mixture control is not the problem and adjusting it will not compensate for other problems.

You need to have a good understanding of the fuel management system for these engines and then armed with that knowledge use your observation and diagnostic skills to determine where the problem is.

To answer some of your more recent questions - yes the plate must not scrape the air horn. Must be centered properly before anything else is done. - The bolt in the center of the plate - loosten it, center the plate, then tighten it. Very simple. The fuel pressure in this system is no more than 100 psi. So your 600 psi guages will work without problems but it would be difficult to accurately read the numbers you are looking for. You need to follow the MB proceedure outlined in the service manuals for checking the pressures.

dpetryk,thanks for the slap,I too felt like I was chasing my own tail,Not at all fully versed on the system I am trying to learn,the gauge would not read in small enough increments if only 100 psi so 200 is OK have some of those too.j-n-t

This sounds like your pressures are off in the opposite Lean direction. They are adjusted with the EHA and I don't think you need the guages, I'm sure I'll get corrected if wrong, but I didn't need them. you just need the current and ratio. Its not hard, just that the two compensate for each other. One is to the right of ) and the other is left by the same distance. The farther off 0, the bigger the difference in the idle and 2000 ratios; Just like what you are getting. If your EHA is lean you have to go rich on the mix. It is easy to tell If you go the wrong way, it will just get worse.

Start by measuring the current, I bet its + a few mils maybe 6 to 8 and moving +- 1. Mine was about 2. Take off the EHA module, the gas pressure, about 80lbs, will bleed quickly and spray a bit. (I have no clue why clever Germans couldn't put the adjustment on the other side so you don't have to take the module off for each adjustment.) Uncover and turn the 2mm TINY brass allen screw (careful it has no friction and its hard to know when the allen is seated. I suggest you blow the gas out of the allen and visually see how the alen is oriented.) I'm guessing CCW, 1/4 turn. I also guess 1/2 turn will be closer. Put it all back together and readjust the mixture ratio, (leaner?) Look at current I'll bet + a few miliamps. And the ratio difference will be close. Keep iterating until you get +-1ma centered on 0 current, 50% ratio, <10% difference and 700rpm idle. Mine took about 5 trys.

But it is neat when you know its right.

Ok my Friend will try today,took the car to Shreveport and it ran fine to but on the way back it stalled several times,I unplugged the icv and after several try's it Finlay went to high idle, before that it just stumbled and choked,perhaps I am going to have to buy a new Icv.well let me get started on this. j-n-t

try as I may I only have a cheep old meter and on a setting of 10 volts dc I got a reading of 3.8 volts over both of the lines one black and the other brown with black stripe, Removed the EHA and turned the allen 1/2 ccw then tryed to reset the mix ran like mud.so back into it and cw 1/4 that gave a great deal of even eng. flow once the mix was reset, but I am still getting the same voltage reading,at the EHA.
Now the lamda reading is at 4.4 to a slow rise or I should say a stedy rise to 5.4 even up and down rampping 68%
2500, was 6 volts at 56% hope I did ok.

It is technical, how to use a (V) volt meter to measure I (current). The resistance of the EHA is probably so high that you have no resolution on the voltage change. It could also be controlled voltage so the current changes but the voltage is held constant.

You need a 1 or 10 ohm series resistor I wouldn't encourage you to do it. Are you saying you meter doesn't have an (DCA) direct current amps scale or (DCMA) milliamps:less than one amp? It might just be labeled without the DC.

If so ~20 - 30$ will buy a good enough multimeter at Homedepot or Radio Shack. Try asking the sales guy for a meter that will measure just a few miliamps. They will at least be able to show you where on the meter to look for the current scales.

Covered you on the other measage too. You might want to start a new post to bet braoder help on how to measure, adjust and balance the the EHA and mix.

The slow rise means the two are not centered on their control range. what do you mean by even engine flow? Smooth rather than rough or surging of surching? It is helpful to say where the idle ended, high means you are rich and low means you are lean.

Getting to the balance takes some imagination and perception. When the mix is in the 60's the EHA needs to go to where it pulls the mix to 50%. ie., Starting at 60%, ( i think that is lean so EHA is set too rich) go anothe 1/8 cw. Now which way does the % go? If higher like 70%: wrong way. Go back 1/4 ccw (now 1/8 ccw from where you started.) % should go below 60% and you are going the right way.

When you get close, the voltage and rpm will not ramp and peg or ramp and quickly start the ramp again. It will hunt, jump around, in the same voltage area, at 2000 the voltage should be the middle of idle movement and not off outside the idle range. The only way you can get ther is to get the EHA current to zero +- just a little. That means centered at zero. And, The % will allow you to adjust it to the same % at both idle and 2000.

Stay in there.

Current! I dun know
 

Yes I shall keep on trying, It has been said you cant teach an ol dowg new trics, But I say ya can jest takes longer.
Well I had such high reading at the Eha that I put the meter down said to my self self must be somptin wrong.
Cousin Kennith has a digital unit I will use his as for mine I tried to get pics of it but my camera will not focus in on the tiny thing. It dose have MA 0.5,10,250 and 1.5 volts dc and ac scale but I cant read any # below 0.

As for the flow of the eng. what I was trying to say, was the eng. got very smooth and slow rhythmic search at one volt rise and fall back to start, say 4.4 to 5.4.
Went back to Shreveport today and started the trip with the eha unplugged was hard to get it to take the fuel, plugged in and it took the fuel ran very well till we started home it shuttered two or three times then cleared up,Though I did notice at 55 to 60 mph on cruse control it had a shutter took it off and it was fine tested this several times same result,so a smoke test will be used to see if I have another air leek.
By the By I have a sight for you look up air flow meter pot my name look into the two sights cool.:idea2:

I'll look you up, you are notorious? See how much fun we are having?

Did you do the smoke? I've never done that, can you see the smoke being sucked into the leak?? I'll assume you still have to adjust the EHA:

1 "eng. got very smooth and slow rhythmic search at one volt rise and fall back to start, say 4.4 to 5.4." Wow, sounds like you nailed the idle mix adjustment. But, when you raise the rpm to 2000 (pull the plug to the ICV will get you close enough), does the voltage stay right in the middle of that range. Or, does it move off to one side and stabalize not at 5V? These two readings along with idle rpm tell you how well the EHA is set. I'm guessing your 2000 is not at 5.

I'll assume you need the EHA current reading and once you get EHA I right and the two mix V settings right, the car should run great. If not you have eliminated a lot got the fuel adjustment right on and know a lot more about what is not wrong.

2 "Well I had such high reading at the Eha that I put the meter down said to my self self must be somptin wrong." What was the reading??? We need #'s...

3 "It dose have MA 0.5,10,250 and 1.5 volts dc and ac scale but I cant read any # below 0." Cool, that is what you need. You need the 0.5MA and 100ma scales. .5 is close to 0 but if you have 6 to 8 ma at the EHA, the 10ma scale is needed. The 100 is needed to check the polarity and connections with ignition on eng off.

I'm suspecting you don't know how to use an amp meter. If so, read the next two paragraphs carefully: It is not connected like a volt meter:you have to open the circuit. It this case just pul the plug to expose the pins and connectors. The meter goes in one side of the circuit like a switch to a light, in 'series'. It jumpers, closes the circuit on one side, going between, the plug on the EHA and the socket that connects to that pin.

Get a jumper wire with allegator clips on each end, or rig one with a small wire like sprinkler or bell wire: paper clip size wire. Strip the ends about an inch. Pull the connector from the EHA. Wrap one end of the wire around the pin closest to you on the back of the EHA. Get a few turns on it to hold it on and give a certain connection. put the other end into the connector that would go to that pin: fold the end back on itself at least once so it holds itself securely in the socket. That makes one side of the circuit.

Now connect the meter leads the same way: one lead going to the pin and one going to the socket. The meter is now in series on one side of the EHA, the other side is jumpered and you are ready to measure.

Be careful not to let the wires touch metal. They are hot and connecting to ground may damage something!!! The meter is technically a short the EHA will get the same current and opperated normally with the meter in series.

To check your connections, Turn on the ignition and you get 25 or 75ma. If it pegs the needle left, polarity needs to be reversed. Just swap the connections at the meter. This is now + current. Up scale the meter to see the reading. Start the car and you should be measuring the EHA current for the temp of the engine. Get it warmed up and it should prop to a few ma. If it pegs south, the current is now negative, reverse the meter connections and down scale to see what you have and write it down.

Adjust the EHA screw 1/8 turn, Air Mix will now be off for the new amount of gas and you need adjustment the mix. Here is a trick: write down the idle and 2000 numbers. They should be different by how much of a change you made.

And, You may have missed this: the mix ratio at 2000 needs to stay right in the middle of the idle range. I'm sure yours won't be, ie 3-4 at idle, 6-7 at 2000. adjust to get back to 5+-.5. And when you are close, the 2000 reading will be very stable like 5+-.1, fun. Last the idle needs end up at 650. Too high and the mix is too rich, too low, guess. If you can't get them to 5 with smooth, 650 idle, say the idle is high, it means too rich EHA, low idle means too lean EHA.

Your turn,

Ok dude the no. are on another sight remember the ones I told you to check out? well I started another thread to pull more info in from the authors of those sights.I did allot of testing today and have a great deal of #s down in that sight, BUT I did not test the EHA in series,never even gave that a thought.SOOOO I will test more tomorrow and give up those to ya.j-n-t

Air flow meter readings by me

Eha Readings
 

Well I think the mark was finally hit,I have -0.0 to +0.01 at idle and holds the same threw 2000, so we should be just in the ok doo kay spot.
The power is much greater and the fuel mileage is better too!
Fuel mileage has increased by 1.6 mpg. to a respectable 19.5 mixed driving.
The next task is the potentiometer,and fine adjustment of this unit. POT. has been installed and improvement is noticeable though I am not ready to voice a complete opinion of the job, I feel the need to investigate the fine adjustments, before I say I am happy, As always I will keep you all informed of the results.jNT:D