So as the title says rough idling during start ups cold or hot, but only hot after car has sat for a bit. Here's what I tested and all tested were carried out following the service manual.
1) fuel pressure, passed
2) cold start valve, passed
3) coolant temp sensor, passed
4) idle air valve, passed
5) all electrical components of ke-jetonic (plugs, wires, cap, rotor, ezl, mas, ecu, o2 sensor, ovp, eha, etc.) All passed
6) compression test of all cylinders, passed
7) vacuum leaks, passed

I just realized that I did not check the fuel injectors for leaks, though the injectors were purchased brand new about a year ago. I'll test them tomorrow. I'm curious as to what anyone else has experienced with a similar problem and what the solution was. I'm also curious about the air/fuel mixture, I tested that as well, but I've never had an oscilloscope or dwell meter g to know what the actual mixture was, however the fsm states to disconnect and plug the fuel evap hose going to the throttle body and increase the rpms to 2500. The% given on the x11 port should not deviate more than ±10. So what I did was set the multimeter to VDC, increase the rpm to 2500 and then took the fluctuating number I saw from that to set the mixture so it was within spec. The voltage range was between 2.5v - 3.8v. I know this is not the correct way to do this, but logically it made sense and even after cranking the mixture to the extreme left and right, when running the rpms up to 2500, I still got the same numbers, so I believe the values are close enough to spec. I also must mention that once the rough idle phase passes, the car runs smooth. Also there are no codes stored.

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1990 190E 3.0L

I decided to take out the injectors and fuel distributor. The injectors were fine with no leaks, spaying a fine mist, and opened at the correct pressure. However, the fuel distributor was interesting. While everything functioned as it should, even had a soft rubber boot that was replaced same time as the injectors, the air flow plate was grossly out of spec by about 8 or 9 mm. The top of the plate should rest flush with the top of the tapered opening with no more than 0.2 mm deviation above the opening. There is a guide pin that you can use a punch and knock the pin in to make adjustments. I did this and recalibrated the air fuel mixture and that seemed to have resolved the problem. Another thing which is very noticeable is the responsiveness and acceleration of the car. I never had a chance to drive a 201 brand new, especially with the 3 liter engine, but I imagine it must've felt similar. Also the car has likely been out of spec either before I purchased it nearly 20 years ago, or shortly after. The I now have to use light pressure on the gas pedal otherwise the car wants to launch forward. I'll continue to monitor, but so far so good.

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1990 190E 3.0L

Good catch!

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1993 2.6 Sportline 5 speed
1992 2.3 Canadian delivery

So the car wanting to launch itself forward ended up being a problem as I found myself barely applying any pressure to the pedal at all and the car rapidly increasing in speed. Though it did climb steady without any of the high revving and downshifting as with trying to overtake a car. So I took the FD off again and checked to see if I had missed anything and upon reassembly I discovered that the airflow meter boot that sits on the throttle body was actually being grazed by the accelerator linkage rod! No wonder. I adjusted the air cleaner housing bushing by raising it up a few millimeters and the problem seems to be corrected. Glad that linkage didn't get stuck or hung up on that boot otherwise that would not have been good.

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1990 190E 3.0L

So whatever I did ended up greatly compromising fuel economy.....I'm talking maybe 12 to 13 mpg highway. Needle was at halfway mark when I left home with 146 miles, now it's between the R and the last bar at 182 miles. Blue smoke at idle with engine idle surging up and down between 500 and 1000 rpm

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1990 190E 3.0L

Hmm.... probably best to retrace everything you've done so far. Could you split the difference of the adjustment made to the height of the plate?

Do the spark plugs have buildup on one side of the insulator? Rough cold idle, blue smoke and if it's there buildup on one side of the insulator can be valve seals. They're relatively easy to replace, based upon what you've done so far you can reply them.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

After you reset the AFM plate height, how did you recalibrate the mixture? If you unplug the OVP does idle still surge?

I noticed that you have a 3.0 in your 190e. Did you swap out the ECU, AFM, FD too?

I like the way Steve Brotherton sets the initial mixture. With the EHA unplugged , you read the voltage of the signal wire of the O2 sensor @80C. You want to see the voltage oscillating around .45vdc. This is the range that the ECU -EHA can react and achieve lambda. You then of course, plug the EHA back in.

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1993 2.6 Sportline 5 speed
1992 2.3 Canadian delivery

I retraced the steps last night, and decided to put everything back the way it was. I bought and replaced the air meter boot below the fd. The engine is a 3L and all the seals, rubber, filters, and injectors are replaced, including the fuel pressure regulator. Ecu is the same, but car ran fine before I recently tampered with it, so I put everything back, pre- my adjustments, even the air plate, the one thing that I can say that isn't back the way it was is the air-fuel mixture screw. I thought my method was correct, but though it made logical sense the way I did it, I'm not so sure. I don't have a dwell reader, so I used the voltages on the x11 connector positive lead of multimeter set to vdc to pin 3 and the negative lead to pin 2 (gnd), engine idling the numbers are jumping around from 12.5v to 12.7v. Before the numbers were 2.5v to 3.4v. I am unable to get those numbers now from adjusting the af mixture in any direction. If I try to get the number lower going ccw by minute turns, once it gets to where the numbers will drop, it just continues dropping until it idles way down and stalls out at about .07v or less. Not getting any codes though, however, fsm mentions that you can also get non-stored "errors" in the form of reading the on/off ratio. I know how to get to the on/off reading, but I don't know how to do it with just the multimeter voltage. Pin 2 and 3 shows 8.5v - 8.7v with ignition on engine off when car is not having any issues. I know that doing the koeo reading in a California car with no issues should show 85% duty cycle. So would that 8.5v be the equivalent using those pins on the x11 connector? Now that car has issues the koeo reading shows 6.4v - 6.7v on pins 2 and 3 of the x11 connector. Would that translate to about 65%? I'm not sure and I'm hesitant to go further down into the rabbit hole by making other adjustments without knowing if it would compound the issue. As of now the car is driveable, but I don't think I can make it even 200 miles on a single tank of gas. I will look at the plugs when I get home and try the suggestions from above as well.

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1990 190E 3.0L

If your VOM reads duty cycle it should function also as a dwell meter. Maybe there is a chart to cross reference the readings. Can tell 'ya that 30° on the 6 cylinder dwell scale is 50% duty cycle.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Mine does not have any of the functions other than A/DVC, resistance, amps(10), mA.

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1990 190E 3.0L

After getting home decided to check for codes since I have about a 45 mile commute. I ended up having error code 17 (O2 sensor signal cable shorted to positive or ground. So I followed the service manual troubleshooting steps Tests #20.0 - 20.8. Typically I start with the tests that check for resistance with the engine off, that way I can easily rule out a break or shortage in the wires which may affect all the other tests. Since I ran most of the tests last night checking the CTS I figured most of the wires were in order, especially since I just swapped the engine last year and redid engine harness and connectors while the engine was out. So I started with test 20.0 which requires plugging in the mm and checking voltage at the ecu connector and sure enough, the voltage I got was .94 with no fluctuation. So the choices were either the O2 sensor, which I previously tested. The wiring, also tested and was good. The ecu, which was swapped out against another and was good, and finally, the mixture. Bingo. Since I now knew what to aim for I slowly turned the mixture screw to see which way was correct to get the voltage to start dropping...(left). Voltage dropped to .76v and began fluctuating. I still had to adjust it ever so slightly to get it to the point where going to RNor D from P, did not cause a surge or sudden dip in idling.

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1990 190E 3.0L

Ok, so I did get the car running fine once again, but I'm still not there with my gas mileage. So I have a favor to ask for anyone that has a good running m103. Could someone please use a multimeter that is set to VDC let their car idle and see what the voltage is by putting the red lead in x11 pin 3 and the black lead in pin 2 and report what numbers they get. Mine are as follows:
key on/engine off: 8.5v - 8.8v
initial start up: 7.0v - 7.5v
after warm up: 12.4v - 12.7v

This won't tell me anything other than my numbers are similar to someone's that is running properly. Moving the adjustment on the air-fuel mixture will change these numbers depending on which way you turn it and so if anyone else has similar numbers then I at least know I can leave it be and look elsewhere.

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1990 190E 3.0L

The issue has been fixed and I'm surprisingly getting 2 mpg more than I did before this whole issue started. I'll keep you all posted if anything else develops

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1990 190E 3.0L