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post #121 of 174 (permalink) Old 01-21-2018, 01:29 PM
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Aufhören mit dem Hinweisen! Einfach klarstellen.

>>See what I said in post 108 about that 5 kΩ connection to engine ground … and note that I mentioned “some other path“ ! …<<

lol, I am not sure what cody is going to do with all of this information. Cody, check that again. Note that you can see a reading (like 5M ohms) if your fingers are on the probes. Crank down the MM setting to 20k ohms max and see what you get.

>>The original post is almost 2 ½ years old … there‘s been some change since then. <<

I didn't see that he solved the overly rich condition.

>> The KE-Jetronic cold start program has fuel enrichment built in by default, not only in most cases. … And that is not switched off when the throttle, or the micro switch, is opened.<<

This is where I was hoping you could educate me. I only have my experience to tell me what is happening and I only have one data point, so my view can be flawed. "Cold" is relative, so the CIS-E, I assume, looks at coolant and intake air temps to tell the IAC how much to open. More when warm and less when cold. Do you agree? I am also very sure that the EHA regulates the pressure differential across the FD to control the fuel delivery but WITHIN limits. I also know that, at least in my case, the injectors spray fuel when the FD is removed from the flapper body (no pressure on the CP in the middle of the FD) and there is no signal to the EHA but, of course, there is voltage to the fuel pumps.

The EHA and IAC are there to do the fine tuning and the flapper is there to do the macro tuning. Do you agree? If so, why would you want the flapper involved in ANY way at idle?

I would also love to know more about how the idle micro switch signal is changing in the fuel/ignition mapping. Clearly closing the microswitch with the car moving fast enough in gear for the RPMs to be greater than the idle RPM should stop fuel flow to the injectors, but I KNOW IT DOES MORE THAN THAT. Do you know what the extra function(s) is (might be)?

I can give you a theory based on experience. Taking the micro switch out of the equation during starting (open circuit) tells the computer NOT to follow the normal cold start mapping which provides the "enrichment" current to the EHA. Instead, the computer only looks at the temp sensors and allows the flapper to control the fuel delivery. i.e. there is no current delivered to the EHA. I may have verified that years ago, but if I did I have forgotten. That is something I suspect you know. Yes? Anyway, if I am correct, then taking the micro switch out of the normal start programming will lean the mixture....but I await your feedback because based on what you wrote, starting the car with the micro switch showing an open circuit should not have made a difference.

Sorry, now that I have your ear, I want as much feedback as you are willing to give. Maybe we should start another thread?
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post #122 of 174 (permalink) Old 01-22-2018, 11:44 AM
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Aufhören mit dem Hinweisen! Einfach klarstellen. ...
Hahaha … I often get to hear this from my students here in Germany (in a little more polite way ) when I give them food for thought instead of detailed & complete explanations … which I often do, because I think that understanding by thinking is deeper than understanding by hearing. …

Quote:
Originally Posted by KJZ78701 View Post
>>See what I said in post 108 about that 5 kΩ connection to engine ground … and note that I mentioned “some other path“ ! …<<
lol, I am not sure what cody is going to do with all of this information. ...
I said that to you KJZ78701, respectively to readers like you, not to Cody. … To Cody I said (in post 108):
“I suggest to start the search by checking the resistance between terminal 13 and all other terminals of the ECU connector, with the TPS connector disconnected !“

But I do think that Cody gained more from this thread so far than you think. …

Quote:
Originally Posted by KJZ78701 View Post
... I didn't see that he solved the overly rich condition. ...
That only looked like an “overly rich condition“, but it was not … it was “weak ignition“. ...

That, BTW, is something by which mechanics are often fooled. They see fouled spark plugs and think “overly rich condition“. And if then they check what the o2 sensor says, they get really confused, because they see low voltage, which urges them to think “overly lean condition“, which is what low o2 sensor voltage usually indicates. … They don‘t know that it can also indicate incomplete combustion caused by “weak ignition“. …

I mentioned that as possibly being the case with the OP‘s car (in post 55) … and, as it turned out later, it was the case.


Since we‘ve already deviated this far from the OP‘s case:


I like your thirst for knowledge, KJZ78701 … very useful, especially in case of the KE-Jetronic. … And your questions are justified and deserve thorough answers … which I would really like to give you. But I‘m very busy with other things right now … and I think that should not be done in Cody‘s thread. So, please accept these quick answers for now:

Quote:
Originally Posted by KJZ78701 View Post
... "Cold" is relative, so the CIS-E, I assume, looks at coolant and intake air temps to tell the IAC how much to open. More when warm and less when cold. Do you agree? ...
How much the CIS-ECU tells the IACV to open depends i.a. on the coolant temperature. The intake air temperature plays no role in IACV control. The colder the coolant temperature, the more the IACV is opened.

Quote:
Originally Posted by KJZ78701 View Post
... I am also very sure that the EHA regulates the pressure differential across the FD to control the fuel delivery but WITHIN limits. ...
That‘s correct. … However, “across the FD“ is a very rough description.

Quote:
Originally Posted by KJZ78701 View Post
... I also know that, at least in my case, the injectors spray fuel when the FD is removed from the flapper body (no pressure on the CP in the middle of the FD) and there is no signal to the EHA but, of course, there is voltage to the fuel pumps. ...
… which can be the case for (at least one of) the reasons I mentioned in my last post.

Quote:
Originally Posted by KJZ78701 View Post
... The EHA and IAC are there to do the fine tuning and the flapper is there to do the macro tuning. Do you agree? If so, why would you want the flapper involved in ANY way at idle? ...
The AFM, in combination with the CP, depending on their positions relative to each other (which can be changed via the adjustment tower between the FD and the AFM plate), takes care of the aerodynamically & hydro-mechanically predetermined air/fuel mixture … which in German is usually called “Grundgemischeinstellung“ (“basic mixture setting“).
The EHA takes care of several things, of which the “fine tuning“ based on input from the o2 sensor (Lambda control) is only one. You might take a look at the following thread for more detailed information about not only this “fine tuning“ via EHA, but also about the “macro-tuning“ via EHA, which can become necessary (depending on the above-mentioned adjustment or depending on possible problems like e.g. false air, leaky cold start valve, etc.):
https://www.benzworld.org/forums/w124...uty-cycle.html

Besides this tuning, the EHA is also there for start-, after-start-, warm-up-, acceleration-, WOT- enrichment and for fuel cut-off during overrun and at engine speed limit, of course.

A quick answer to your question why the flapper is involved at idle, my last post provided already:
“The AFM / FD unit is designed in such a way that the “flapper“ does apply pressure to the CP (Control Plunger) when the engine is running at idle speed … by which the CP is slightly pushed up, thus slightly opening the metering slits.“

Without opening the FD‘s metering slits no fuel flows via the FD‘s upper chambers to the injectors … unless at least one of the reasons I mentioned in my last post is present.

Quote:
Originally Posted by KJZ78701 View Post
... I would also love to know more about how the idle micro switch signal is changing in the fuel/ignition mapping. Clearly closing the microswitch with the car moving fast enough in gear for the RPMs to be greater than the idle RPM should stop fuel flow to the injectors, but I KNOW IT DOES MORE THAN THAT. Do you know what the extra function(s) is (might be)? ...
As a quick answer: The micro switch
- activates idle speed control via IACV (Idle Air Control Valve) (when closed)
- activates overrun fuel cut-off depending on engine temperature & speed (when closed)
- prevents acceleration jolts if during an overrun phase the accelerator is depressed again by opening shortly before the TPS opens.

Quote:
Originally Posted by KJZ78701 View Post
... I can give you a theory based on experience. Taking the micro switch out of the equation during starting (open circuit) tells the computer NOT to follow the normal cold start mapping which provides the "enrichment" current to the EHA. Instead, the computer only looks at the temp sensors and allows the flapper to control the fuel delivery. i.e. there is no current delivered to the EHA. I may have verified that years ago, but if I did I have forgotten. That is something I suspect you know. Yes? Anyway, if I am correct, then taking the micro switch out of the normal start programming will lean the mixture....but I await your feedback because based on what you wrote, starting the car with the micro switch showing an open circuit should not have made a difference. ...
Taking the micro switch out of the equation during starting (by opening it) does not deactivate the “normal cold start mapping“. The temperature-dependent (start-, after-start-, warm-up-) enrichment via EHA control takes place at full volume, no matter whether the micro switch is closed or not. … That, however, does not mean that it doesn‘t make any difference whether the car is started with the micro switch opened or closed. It just doesn‘t make any difference re mixture enrichment via EHA control.

What you experienced with the micro switch on your car had very probably to do with a not very well known peculiarity of the M103‘s (and the M102‘s and M104‘s) IACV.
With the micro switch opened, IACV control is not active and the IACV‘s spring-loaded rotary slide is turned to its stop position, leaving a mechanically predetermined gap for intake air with its “left“ edge.
With the micro switch closed, IACV control is active … however, in that case the gap for intake air is controlled via the rotary slide‘s “right“ edge. When IACV control kicks in, the rotary slide starts to turn away from its stop position, closing the gap with its left edge and opening the gap with its right edge … unless it get‘s stuck after the gap on the left edge started to close and before the gap on the right edge is (sufficiently) open. Along that rotation angle there‘s a position where the IACV is even completely closed for a tiny moment.
So, with a probability bordering on certainty, with the micro switch closed, your IACV‘s rotary slide got stuck within that range (due to contamination) and smothered your engine. With the micro switch not closed, the IACV was currentless and, as it's supposed to, it‘s spring-loaded rotary slide jumped back to its stop position allowing intake air to pass along its left edge, so that the engine could be started. ...

BTW, that “currentless“ gap, formed by the rotary slide‘s “left“ edge, is a little bigger than the average gap controlled by current flow (and formed by the rotary slide‘s “right“ edge) … and that is why idle speed rises a little when you pull off the IACV plug.

If this verbal explanation is not clear enough, I might prepare a drawing, which might make it a lot easier to understand, later.

Quote:
Originally Posted by KJZ78701 View Post
... Sorry, now that I have your ear, I want as much feedback as you are willing to give. Maybe we should start another thread?
I‘d like to do that … but please understand that I‘m currently really too busy. I‘m already putting more time into this than I actually have right now. I‘ve been thinking about starting a thread with a thorough explanation of the KE-Jetronic and how to test it for some time, but never got around to it. … I hope that, for now, the above answers could at least be of a little help. …

H.D.
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Last edited by H.D.; 01-22-2018 at 02:02 PM.
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post #123 of 174 (permalink) Old 01-26-2018, 12:12 PM
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Highly informative as usual H.D. Thank you. Since the subject of the micro-switch has been brought-up I would like if I may to ask a question that I could not find the answer to in W201 or W124 forums.

When there is a slight leak in the fuel system ( I understand the culprit generally is the accumulator) and there is the symptom of the engine stalling after the very first start during "warm" engine, this can be remedied by just pressing the gas pedal slightly during the cranking if the engine sits for 1Hr - 3 Hrs (in my case) and the engine temp is in the range of 50C to 80C or so.

Just curious, what is the dynamic that makes the problem go away by pressing the gas pedal slightly?

(1) Is the microswitch involved in this?
(2) Or is it just the fact that the engine revs up a little after starting and gives the system enough time to build up fuel pressure to avoid the stall until the fuel pressure builds up.

Inquiring minds minds want to know.

- Cheers!
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post #124 of 174 (permalink) Old 01-27-2018, 10:08 AM
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... Since the subject of the micro-switch has been brought-up I would like if I may to ask a question that I could not find the answer to in W201 or W124 forums.
When there is a slight leak in the fuel system ( I understand the culprit generally is the accumulator) and there is the symptom of the engine stalling after the very first start during "warm" engine, this can be remedied by just pressing the gas pedal slightly during the cranking if the engine sits for 1Hr - 3 Hrs (in my case) and the engine temp is in the range of 50C to 80C or so.
Just curious, what is the dynamic that makes the problem go away by pressing the gas pedal slightly?
(1) Is the microswitch involved in this? ...
The answer to that, very good, question should actually be found in a W124 forum rather than in any other forum, because the W124 with it‘s range of engines is the model it‘s most relevant for. … I hope the OP doesn‘t mind if I answer that question here in his thread too. …

Yes, in case of the M102, M103 and M104 the micro switch is involved in this … especially if the warm start problem can be remedied by depressing the accelerator so slightly that the throttle is still closed but the micro switch already opened (with the throttle linkage properly adjusted the micro switch opens before the throttle starts to open) … but also if the accelerator is depressed so far that the throttle is opened.

As I said in my last post, “with the micro switch opened, IACV control is not active and the IACV‘s spring-loaded rotary slide is turned to its stop position, leaving a mechanically predetermined gap for intake air with its “left“ edge … … which is a little bigger than the average gap controlled by currentflow (and formed by the rotary slide‘s “right“ edge)“ … especially when the engine has not cooled down yet.
That bigger gap allows more intake air to pass. This additional intake air, which is, of course, detected by the AFM, pushes the AFM plate a little further down … thus the FD‘s CP is pushed a little further up … thus the FD‘s metering slits are a little further opened … by which, corresponding to the additional amount of intake air, more fuel flows (via the upper chambers of the differential pressure valves) into the injector pipes … allowing more effective “bleeding“ of the injector pipes, in which “vapor locks“ have developed.

These “vapor locks“ are gas bubbles that develop in liquid fuel at reduced residual pressure due to a leak somewhere in the fuel system. They develop especially in the injector pipes … which are exposed to significant heat from the engine under the closed hood when the hot engine is switched off and the flow of cold fuel through them is stoped … and cause warm start problems.

With the accelerator depressed so far that not only the micro switch but also the throttle is opened, even more intake air pushes the AFM plate even further down and the CP further up, which leads to even higher fuel flow into the injector pipes.

BTW, the accumulator is only one of a number of possible culprits for residual fuel pressure loss. …

H.D.
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post #125 of 174 (permalink) Old 01-27-2018, 10:14 AM
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This 126 geek talk fascinates me—even if I read it and get mild anxiety attacks thinking about having to do these things. Familiarity breeds confidence, I suppose. In any event, had I had this forum around when I was a younger guy in my 20s, I might very well have become a mechanic. I can read these boards for hours. And I never guessed I'd know more about a 30 year-old Benz than any other car I've ever owned.
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post #126 of 174 (permalink) Old 01-27-2018, 03:51 PM
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Thanks H.D. for the explanation of the behavior. I will chase down the pressure leak in due time as it is a benign problem at this point.

Strassenkruzer, I had no idea when I bought my car new in '89 and sold it 13 years later that it would come back to me in pretty good shape for me to learn the engine thanks to many in these forums but especially H.D.'s intimate knowledge. I have performed most of the maintenance and trouble shooting with excellent help here.

Sorry for the slight diversion....

- Cheers!
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post #127 of 174 (permalink) Old 01-28-2018, 03:18 AM
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dolucasi i have this hot start problem ,, and after i changed the accumulator it made no change to the start of my m103.
And i have changed lots of other items . One part that was change that made the start up a little better hot, was the coil Only things left that i need to change now is my injectors and seals .,
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post #128 of 174 (permalink) Old 01-28-2018, 07:59 AM
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Quote:
Originally Posted by panzernacker View Post
dolucasi i have this hot start problem ,, and after i changed the accumulator it made no change to the start of my m103.
And i have changed lots of other items . One part that was change that made the start up a little better hot, was the coil Only things left that i need to change now is my injectors and seals .,
I won't blindly change the accumulator then and first see if it is leaking. I have only replaced an externally leaking EHA valve as part of the fuel system but the dealer replaced all the injectors and cold start valve a couple of years ago (for no charge but we won't get into that here). I assume it was done right.

Fortunately this is a benign issue and hopefully is not harmful to the car in any way.
It is time to buy a fuel pressure gauge. I'm sure it will be used in the future....

- Cheers!
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post #129 of 174 (permalink) Old 01-28-2018, 10:16 AM
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Originally Posted by dolucasi View Post
Thanks H.D. for the explanation of the behavior. I will chase down the pressure leak in due time as it is a benign problem at this point.

Strassenkruzer, I had no idea when I bought my car new in '89 and sold it 13 years later that it would come back to me in pretty good shape for me to learn the engine thanks to many in these forums but especially H.D.'s intimate knowledge. I have performed most of the maintenance and trouble shooting with excellent help here.

Sorry for the slight diversion....

- Cheers!
I can relate. I had no idea that when my mother bought her 300SE in '89 and passed away 25 years later that I would inherit it. Maybe she did that because she felt guilty about selling my step-father's 1963 220SE convertible to a private mechanic for—wait for it!—$5,000 right after she bought her 300SE because the 220 wasn't running that well: My step-dad had one night accidentally dumped five gallons of diesel into the tank and then drove it nearly a hundred miles knowing what he'd done—OUCH!) and so she wanted to get rid of it...despite my pleas to keep it. What that would have been worth today in good shape...

Anyway, I digress. Though I have an '03 CLK 430 that I love, the 300SE is still my favorite car to drive, and its build quality is still considerably better than the CLK's. In 2003 I think MB was still suffering the quality slip with the design of the W220 and later that it had to make to compete with the Japanese. The LS400 started the whole thing around 1990, as I recall.

To your point about @H.D. and his thoroughness: Agreed. There are many very capable and patient peeps on this forum who know their stuff, but few can match his insanely methodical and thorough approach to diagnosis and repair. In fact, I've detected from reading long threads that for some it can be off-putting, and I don't understand why that is. I find his comments are always read-worthy...even if I have to google a bunch of terms and go watch videos on myriad subjects to really try and understand what he's getting at—particularly with electrical stuff.
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post #130 of 174 (permalink) Old 03-13-2018, 11:40 AM
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I. Have. A. Mercedes-Benz W210 pretty much sounds like the same problem other than the car idols what I would say RPM fluctuating slightly up-and-down while in park and a bit more when you put it in drive I have change the spark plugs of track down houses sprayed for leaks so far I have not found any I notice when the temperature rises around 90 to 95 that’s when the car seems to change idling speed what may be the problem can we find a solution
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