Lacking any sort of available sensor setup that would fit my engine and work with the MegaSquirt, I made my own crank position sensor using NTE3100's. (It's a long story, but trust me, it was necessary.)
Here's the result from the initial tests on the oscilloscope. Is this signal good enough to work reliably? I'm concerned that the voltage may not be falling off quickly enough to provide the MegaSquirt with a good tach signal. I'm troubleshooting a couple of items on this install, and would like to be sure that the sensor's waveform won't be a problem.
The red trace is the sensor's output. The blue trace is the signal from the Opto-Isolator to the processor.
Is this sensor good enough?
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
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Is this sensor good enough?
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Turbo Lag: Because good things come to those who wait.
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Matt Cramer
- Super Squirter
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Re: Is this sensor good enough?
Looks like the RPM it's picking up is a bit wavery. If it isn't reading a steady RPM, it should probably be OK.
Re: Is this sensor good enough?
That test was done using the starter to crank the engine. You're seeing the RPM's drop as each cylinder hits its compression stroke. So that part's normal, at least.
I thought about it some more, and it seems to me that the processor isn't going to look for a specific waveform. It's just going to look for a voltage above or below a set value. As long as the voltage off of the Opto isn't hovering around switch point for any length of time, the processor should be fine. Is that an accurate description of how the processor handles inputs?
Cheers,
Fred
I thought about it some more, and it seems to me that the processor isn't going to look for a specific waveform. It's just going to look for a voltage above or below a set value. As long as the voltage off of the Opto isn't hovering around switch point for any length of time, the processor should be fine. Is that an accurate description of how the processor handles inputs?
Cheers,
Fred
Turbo Lag: Because good things come to those who wait.
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Matt Cramer
- Super Squirter
- Posts: 2951
- Joined: Sat Jul 03, 2004 11:35 am
Re: Is this sensor good enough?
The opto turns it into an abrupt on/off waveform anyway, so I wouldn't worry too much. May give a tiny bit of jitter but I don't expect a problem.
Re: Is this sensor good enough?
Well, the coils are making sparks when they're supposed to. So I'm going to operate on the assumption that it works.
Turbo Lag: Because good things come to those who wait.