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. …
>>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. …
... 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:
... "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.
... 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.
... 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.
... 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.):
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.
... 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.
... 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“
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.
... 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. …