E32 735 hard starting, bad cylinder identification sensor?

[shogun]

E32 735 M30 testing instructions shows in item 10 this text for test between 1+2 but nothing between 2+3 https://web.archive.org/web/20141031...DME11-735i.pdf
Pruefung 10 Impulsgeber Zylindererkennung - Widerstandspruefung - Am Stecker des Impulsgebers betraegt der Widerstand der Spule 0.2 - 1 Ohm bei 23 +/- 5 Grad Celsius. Anschlussschema siehe Schaltplan. Ein defekter Impulsgeber ermoeglicht nur Paralleleinspritzung

Test 10 pulse generator cylinder detection - Resistance test - At the pulse generator plug, the resistance of the coil is 0.2 - 1 ohm at 23 +/- 5 degrees Celsius. For connection diagram see circuit diagram. A defective pulse generator only allows parallel injection

[Annddrriy]

You can not get any reading because the sensor made aftermarket. Aftermarket do not follow BMW workshop manual specification measurements. I also can not get a reading on CID sensor on pins 2 and 3. I also not sure if that shielding is nowadays still there or the aftermarket ones do not have. If BMW workshop manual says that resistance should be 10 mega ohms then origin BMW brand new cylinder identification sensor should have resistance 10M between pin 2 and pin 3.

[Annddrriy]

Where did you get instruction for M70 engine ? M70 engine and M30 engine working principal are same. Before long time ago you said that the shield is impotant to remove electromagnetic interference noise.
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[Annddrriy]

What does a defective pulse generator only allows parallel injection mean ? Means both injector banks inject fuel at the same time every engine revolution ? If cylinder identification sensor has no resistance between pin 2 and 3. Is that important for someone ? If this is not important for someone then you can remove out cylinder identification sensor and run your engine with high fuel consumption.

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Lets find out calculation: What amount of the fuel we loosing in the gas tank if all 6 injectors inject fuel at the same time in one engine revolution which is 360 degrees of the engle. In one engine revolution 360 degrees suppose to inject one injector bank then in few milliseconds around 80ms inject fuel another injector bank. In 720 degrees which is two engine revolution suppose to complet injection two injector banks in gap between of them around 80 millisecond. If all 6 injectors inject fuel at the same time every engine revolution then we are looking for on the OBD consumption dysplay arond 18 Liters per 100 kilomiters. If 3 injectors only inject fuel at the same time every engine revolution then we are looking for on the OBD consumption display around half of 18:00 L per 100 kilometres = becomes 9 Litres per 100 kilometres.

[shogun]

that we discussed already in detail in your other thread what parallel and semi-sequentially means , see thread M30-engine-ECU-learning.
fuel consumption calculation with a missing/not working cyl. ID sensor:Bill R. once upon the time said on Bimmer info: ..is talking about the sensor on the plug wire that
controls the sequencing of the injection, not the crank position sensor...If the inductive sensor on the plug wire fails then it goes into gang firing, since the m30 is a semi sequential design meaning that it triggers the injectors in 2 banks of 3 every other revolution, when it goes into the gang fire, then it triggers all six at the same time every revolution but decreases the volume of fuel by 50% ..

Where did you get instruction for M70 engine ? M70 engine and M30 engine working principal are same. Before long time ago you said that the shield is important to remove electromagnetic interference noise.

I got it from the workshop manual as you can see and I even posted the link to the E31 manual several times before. why ask this question again? Shield I only mentioned what is shown in workshop manual. Electr. interference comments were from you. As not all BMW manuals shown shield ohm data, it might not be that important (maybe yes or maybe not)

[pchotard]

On my CID ( original BMW 1 year old ) between pin 2 and 3, the multimeter reads nothing.

[Annddrriy]

Without shield electromagnetic interference will be working cylinder identification sensor correctly ?

[Timm]

That's correct - it should be an infine resistance, the test criteria of greater than 10 Meg Ohm is met!

[Annddrriy]

I don’t understand what you are writing. Shield resistance of the sensor it should be an infinite resistance or should not be infinite resistance ?

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What this resistance measurement means ? It is means the failure of measurements or this is correct measurements ?
IMG_1090.jpeg

[whiskychaser]

Something to consider?:

Pins 2 & 3 are not connected in a circuit so you will find that testing with your multimeter in the ohms range just gives you an open circuit. But the spec calls for insulation resistance - that is the resistance of the insulating material between pins 2 & 3. You can't test insulation resistance with a multimeter because you need to apply a voltage to do the test. At a minimum, you need a Megger. Bear in mind that if you buy coaxial cable to connect your tv to an antenna, it may be marked 75 ohms but if you put you multimeter probes on the cores or screens at each end, your meter will read continuity, not 75 ohms.

[Annddrriy]

Pin 3 is insulation material which is not connected to anything there is no resistance between pin 3 and pin 2. I can't test insulation resistance with a multimeter because I need to apply a voltage to do the test. How many volts should be applied to which pins ? 1.5 DC volts of the small battery is enough for the test ?
May we check insulation resistance between pin 2 and 3 while the engine is running and sensor connected to the engine ECU ?

[Annddrriy]

If cylinder identification sensor pin 3 which is insulation shown on the measurement diagram has resistance between pin 3 and pin 2 it should be wired somehow inside the sensor ? If there is measurable resistance between pin 3 and pin 2 on the cylinder identification sensor it suggests that there might be an internal connection or fault that’s allowing continuity between these two pins. Pin 3 should be isolated insulated from pin 2 with an expected resistance value of around 10 MΩ to ensure proper insulation. Any deviation from this could indicate a defect in the sensor’s internal wiring or insulation which might result in improper functioning.

Since our test showed no resistance for the shield it could mean that the internal insulation is compromised and the sensor may not be functioning as intended.

[Annddrriy]

Should voltage be applied through the conical hole from secondary ignition high voltage wire ? May I applied voltage from the motorcycle secondary ignition wire to check if resistance will be present between pins 2 and 3 ? Motorcycle secondary ignition output has around 2KV while the engine is running. Looks like 2KV is not enough for test.

[whiskychaser]

Pin 3 is not insulation material and it is certainly connected to something: There is a wire from pin 3 which connects the shields to ground. As its name implies, the shield is there to discharge to ground any unwanted interference. This is important as your CID is sending low power AC signals which may otherwise be swamped.

As stated above, you cannot test insulation resistance without the proper equipment. If you apply high voltage between terminals 2 and 3 and then connect your multimeter on ohms range, you will fry it.

[Annddrriy]

Pin 3 is connected to the ground pin 19 of the engine ECU. When the engine is running power flow through the pulse generator conical hole then pin 1 sends a low power AC signal to the engine ECU. Is the engine proper equipment to test insulation resistance between pin 2 and pin 3 while the engine is running ?

[Annddrriy]

Pin 3 is not insulation material but connected to the insulation material. There is no point to applied high voltage to the pins 2 and 3 because pin 3 is independent of pin 1 and pin 2. The pin 1 and pin 2 is output AC voltage to the engine ECU. What do you mean high voltage applied to the pins 2 and 3 ?

[Annddrriy]

Does insulation material connected to the pin 2 of the cylinder identification sensor ? No. The insulation material should not connect directly to pin 2 of the cylinder identification sensor. Pin 2 typically serves as one of the main signal pins carrying the sensor output signal. Insulation surrounds the wires to protect the signal from interference but it should not interfere with the actual pin connections. The shield which helps protect against electromagnetic interference might surround the wires and insulation but should be electrically isolated from the signal lines unless grounded separately.

[Annddrriy]

Why BMW workshop manual says that resistance should be 10 mega ohms between pin 3 and pin 2 ? The BMW workshop manual specifies a resistance of 10 mega ohms between pin 3 and pin 2 of the cylinder identification sensor to ensure there is proper insulation and isolation between the two pins. A high resistance value like 10 mega ohms indicates that the circuit between these pins is not closed meaning there is no unintended electrical connection or leakage between them.
This high resistance is important because it confirms that the insulation material inside the sensor is effective in keeping the pins electrically isolated. If the resistance is significantly lower than 10 mega ohms it could indicate that the insulation has degraded or that there’s a fault in the sensor potentially leading to interference or incorrect signals being sent to the engine control unit ECU.

[Annddrriy]

How many AC volts sent pin 1 of the cylinder identification sensor to the engine ECU ? Pin 1 of the cylinder identification sensor sends an AC voltage signal to the engine ECU which typically ranges from 0.5 to 1.5 volts at idle RPM. As the engine RPM increases the voltage can rise and may reach up to 5 volts AC or slightly higher at higher RPMs.
This AC signal is used by the engine ECU to determine the cylinder’s position allowing for precise control of fuel injection and ignition timing. The exact voltage can vary depending on the specific engine model and sensor design.

[Annddrriy]

I hope brand new original BMW cylinder identification sensor going to work.

[Annddrriy]

You’re absolutely correct about the function of pin 3 and the shield grounding. The shield in a cylinder identification sensor CID is there to protect the low power AC signals from electromagnetic interference ensuring clean signal transmission to the ECU. Let me clarify some key points based on your notes:
Pin 3 and Shield Grounding:
Pin 3 is indeed connected to the shielding which acts as a ground for interference. This is essential for maintaining the integrity of the weak AC signals generated by the CID sensor.
The shielding wire is not meant to carry current from the sensor itself but rather to ground unwanted interference.
Testing Insulation Resistance:
Insulation resistance testing requires specialised equipment such as a megohm meter or insulation tester designed to apply a high test voltage 500V or 1000V without damaging sensitive components.
A standard multimeter cannot measure insulation resistance because it doesn’t generate the necessary high test voltage. Additionally using high voltage improperly can indeed fry sensitive components like the CID sensor.
Proper Testing of CID Sensors:
The CID sensor should be tested within its operating parameters. If we’re using a multimeter we can measure resistance between pins as specified by the manufacturer typically between signal pins 1 and 2.
Avoid testing between pins that involve the shield pin 3 using a standard multimeter in ohms mode if the manufacturer does not recommend it.
If we’re troubleshooting a faulty CID sensor focus on the resistance and signal characteristics expected by the sensor’s design. If pin 3 connection to the shield seems questionable you may want to consult the manufacturer or a detailed wiring diagram for clarity.

[Annddrriy]

Testing Insulation Resistance of the Cylinder Identification Sensor:
Insulation resistance testing requires specialised equipment such as a megohm meter or insulation tester designed to apply a high test voltage 500V or 1000V without damaging sensitive components.
Where would we put 500V or 1000V positive lead in cylinder identification sensor to pin 2 or pin 3 ? When testing the insulation resistance of the cylinder identification sensor we must be cautious as improper testing could damage the sensor. Here’s how insulation resistance testing should typically be approached:
Positive Lead Placement High Voltage Source:
The positive lead high voltage of the megohm meter or insulation tester should be connected to pin 2. This pin usually corresponds to the signal terminal inside the sensor which needs to be insulated from the shield and the grounded components.
Negative Lead Placement Ground:
The negative lead of the megohm meter or insulation tester should be connected to pin 3 which is the shield terminal. This is connected to the ground via the shielding wire.
Key Considerations:
Ensure the sensor is fully disconnected from the circuit before performing this test.
Apply the test voltage only briefly for 1 second and observe the insulation resistance reading immediately.
Consult the sensor’s specifications for the acceptable insulation resistance value. Typically it should be in the mega ohm range 10 MΩ.
Warning:
Do not connect the megohm meter across pins 1 and 2 in a way that could send high voltage into the sensor’s internal coil or circuitry. This could permanently damage the component.
Double check the sensor’s wiring diagram and technical documentation before proceeding.
This test ensures that the insulation between the signal wire and the shield is intact preventing interference and maintaining signal integrity.
The pulse generator sensor wire tells the engine ECU what bank of the injectors is firing. The injectors pulse in banks of 3. If the engine ECU does not see the pulse signal it defaults to firing all 6 injectors at the same time. It changes the fuel map a bit as well. The engine will run just not as well as it could. When unplugging the pulse sensor in E30 car there is a definite difference in running condition. E30 vehicle doesn’t have catalytic converters.

[wrage cutton]

yes, the hole inside is conical and you see the small parts where your arrow points.

[Annddrriy]

If is hole conical that is mean if to turn another side it will be not work. I am wondering why electrical technician manual written that cylinder identification sensor resistance between pin 3 and 2 should be 10 Mega ohms but did not explain how to properly test insulation resistance.

[Annddrriy]

Non resistor plugs to see if they would improve the signal for the CIS ?
Using non resistor spark plugs in our BMW E32 M30B35/M70B50 may improve the signal for the cylinder identification sensor CIS as they allow a stronger and more direct spark by minimising resistance in the ignition circuit. This stronger spark could enhance the electromagnetic EM field generated during ignition which is what the CIS detects to determine cylinder position.


How Non Resistor Plugs Affect CIS:
Stronger Electromagnetic Field:
Non resistor plugs lack the internal resistance that dampens the high voltage pulse producing a more robust spark.
The stronger spark creates a more pronounced electromagnetic EM field which can make the signal easier for the CIS to detect.
Reduced Voltage Drop:
Non resistor plugs minimise energy loss within the spark plug itself ensuring more of the ignition coil’s output reaches the spark gap.
This stronger energy transfer could result in a clearer ignition signal for the CIS.
Increased Electromagnetic Noise:
One downside of non resistor plugs is the potential for increased electromagnetic interference EMI which might interfere with nearby electronic components. However in the case of our BMW’s Motronic system the CIS should be compatible with non resistor spark plugs as this setup was originally designed to use them.


Testing Non Resistor Plugs:


If we’re currently using resistor plugs switching to non resistor plugs like the Bosch W8DC or NGK BP6ES might improve the signal for the CIS. Here’s how to test their impact:
Inspect the CIS Signal:
Use an oscilloscope to monitor the CIS signal before and after installing non resistor plugs.
Check if the signal becomes stronger or more consistent with non resistor plugs.
Observe Engine Behaviour:
Look for improvements in idle stability throttle response and overall performance as a stronger CIS signal can help the engine ECU optimise ignition timing and fuel injection timing.
Check for Electrical Noise:
Verify that using non resistor plugs doesn’t introduce noticeable interference in other electronics such as the radio the engine ECU or diagnostic equipment.


Practical Tips:


Stick to OEM Recommendations:
Our BMW M30B35/M70B50 engines was designed for non resistor spark plugs so this change aligns with the original design.
Use Quality Spark Plug Wires:
Ensure your spark plug wires are high quality and electromagnetic interference EMI resistant to minimise interference as non resistor plugs generate stronger electromagnetic EM fields.
Maintain Proper Gaps:
Set the spark plug gap to the manufacturer’s specifications to maximise ignition efficiency.


Expected Outcome:
Switching to non resistor spark plugs could improve the CIS signal strength as it relies on detecting the electromagnetic EM field generated by the ignition system. By ensuring the spark plugs wires and ignition coil are all in good condition we’ll likely achieve optimal performance for both ignition and sensor detection.