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So, I go back to this old topic. I repeated the same story as Mike. The crankshaft sensor is damaged. Is there a method for checking it? Maybe by resistance? And how to check the electronic control unit? Did someone understand the situation with the marks on the flywheel?

It seems that now the system sees a "0" point and gives the command to start the engine. But does not see the speed and don't give the command to ignition.
 

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Discussion Starter #22
Only news I can add now is that the control unit seems to be easily checked and repaired. DJMink on this board had good success with a local electronics guy. The unit is pretty simple, so a good old time electronics guy should be able to check and repair diodes, capacitors, broken solder joints, etc.

As for the sensor, I do not know if anyone has determined replacements.
 

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And what do you think about the flywheel? Are there any special marks on it besides the missing tooth? In fact, the sensor reads two parameters. One - to start the engine. The second determines the moment of ignition. Does this mean that there are 2 marks on the flywheel?
 

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Discussion Starter #24
I understood there were magnets embedded in the flywheel that the sensor read (I thought two of them) not missing teeth.
 

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I have not abandoned my attempts to solve the sensor problem. To do this, we first simulated the circuit of the control unit on paper and understood the principle of processing the input signal. Then made a simulator of the ignition system. Tday, the system works "on the table." The next stage is checking by car. Unfortunately, there is a lot of snow in Moscow this year. So I can't dig out my garage yet, so that I could transport Alpina to the workshop and continue my research. But the first results are encouraging.

https://www.youtube.com/watch?v=mb69vGB4mfM
 

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Discussion Starter #26
Very interesting!

Do you have a magnet mounted in that toothed wheel? Or is it counting teeth?

On the car, the teeth are the starter ring gear, so there are no "missing teeth" to count as in most common systems.

I understood that there were magnets mounted in the flywheel that the sensor was reading instead.

What have you found out so far?
 

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For a start, I found out that a similar system was used only on one car, namely, on a Porsche 924 turbo. And talked with the guys who repaired such systems. They told me that there is 1 magnet in the flywheel. Then I just took any gear and sawed off one tooth, and instead of it glued a piece of magnet. Made a mockup with electric drive. (The wiper motor performs this function well, plus it has 2 rotational speeds). After the defect of my original sensor (like you) in the control unit there was a short circuit. So the block diagram we drew helped to identify the faulty chip, and we replaced it. Finally, the most important problem was the selection of a sensor with similar parameters. As you know, until now no one could find anything similar. But I had the opportunity to experience a very large number of sensors. We still had to modify one of them, the closest in terms of the resistance of the coils. Now it no sense to talk about what kind of sensor is question. I'm not sure that it will work correctly at high revs. But we are not in a hurry. Our main task was to get a spark on the spark plug. The next stage is the installation on the car, the definition of the gap to the teeth of the flywheel, checking work in real conditions. I think it is necessary to adjust the sensor parameters with the help of additional resistors or capacitors.
 

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Discussion Starter #29
Ah, how did I forget! I knew the early 924 turbo had a Siemens-Hartig ignition, but forgot!

The 924 sensor (93160602100) looks identical to the original Alpina "Rafi" branded sensor. It is also no longer available from Porsche. The 924 world thinks they are the only ones with this problem. You could try to find a 924 Turbo sensor, but the Porsche people are hoarding them now, too.

If you think the 924Turbo sensor would work, the Porsche community has much better resources, and could (should) start pushing Porsche Classic to re-release a replacement sensor. They are surprisingly responsive in supporting their older cars these days.

Also, have you looked at my threads on this board? A previous owner of one of my cars appears to have sourced a replacement at some point. Attached are pictures of the original Rafi sensor, and another Bosch looking one, with a part number take on it. Another clue?

You are well on the way though. Great work! Look forward to hearing if it works on the car.
 

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I have already talked in Moscow with the director of the Porsche Center. He claims that the sensor problem is known. But while the factory does not help. The sensor number in the photo is not a Bosch number and is not related to the manufacturer number. On my sensor - the same. Such sensors were supplied by Alpina at the end of the 80s, when Rafi was unavailable. I have already probed manufacturers of such sensors in Germany. No one else wants to do this.

One of the best guys, who understands the electrician of the old Alpina very well, lives in Germany. I had a long conversation with him on this problem. He is now trying to create a similar sensor himself. And with improved features. But the price of such complex work will be high. I'm sure he will succeed. For my part, I am trying to find an inexpensive solution. If I'm not lucky, I'm sure Oliver will do it very, very well.

Of course, I began to study the problem with reading your threads. As a matter of fact, it was your thoughts that I based on my experiments. The easiest way is to remake the system into a modern control module. But I am Russian. And the Russians are not looking for easy ways. ;)
 

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Discussion Starter #33
Yes, I noticed that in the Porsche pictures I found. There is a 924 Turbo parts car not too far. I may have to go look for the sensor...

It is strange to me that Alpina did at one time find a replacement sensor (like the second one I have), but now has no idea.
 

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As I understood from my conversations with the Germans, this new sensor was manufactured in limited edition especially for Alpina. Maybe it was ordered from some small producer. But I’m almost sure that this is not done by some giant like Bosch.
 

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Yes, the weather is good. I brought the car to my auto service. Began to experiment. The engine started, but there is a feeling that the countdown of the first cylinder is lost. That is, we see unstable work, and as if there is constantly no ignition in one of the cylinders. We decided to start to replace all the parts in the control unit.



https://youtu.be/SZubsYMtBuA
 

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Discussion Starter #37
Hmm, unstable idle on a CIS system usually says vacuum leaks. Sure you don't have any, maybe around injectors?
 

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Yes, I'm sure everything is tight. You see, it feels like it constantly misses the ignition in one cylinder. And on each following cycle - in another cylinder. Something like this: 1_1111; 11_111; 111_11; 1111_1; 11111_ and so on.
 

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One of the best guys, who understands the electrician of the old Alpina very well, lives in Germany. I had a long conversation with him on this problem. He is now trying to create a similar sensor himself. And with improved features. But the price of such complex work will be high. I'm sure he will succeed. For my part, I am trying to find an inexpensive solution. If I'm not lucky, I'm sure Oliver will do it very, very well.
Hi,
I am the German guy who will sort it out, the problem is the sensor construction itself and the way the sensor is talking to the ignition box. The air gap between the sensor and the flywheel was very important, also very cirtical.
First of all I organized an original automatic flywheel yesterday. It will be prepared for exact the same condition.
The missing cog is the cylinder blanking it is the same like on modern incremental wheels. Important about this point it was not set on the upper slack point. After that I will modify a test setup for exact the same conditions, the speed should be between 400-7000 (rpm). To control the flywheels speed I will reprogram one of my development tools, so I can set a static speed to an electromotor who will spin-up the flywheel at the corresponding engine speed. This scenario I have to do for the complete speed range. At the same time I will monitor the signal output and save the waveform information digitally (my development tool will do this). The signal output and waveform of the coil is the important part here. The waveform is changing over the speed, but the missing cog have to be recognized over the complete speed range. Therefore the coil parameters have to be rebuild in exact the same way. Later I will see if I rebuild the coil, or use a BOSCH sensor (from my point of view better) and build a digital unit to adapt the sensors signal with a ADA convertion.

@Redox
We will see us in Germany soon.

Greetings Oliver
 
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