OK... I have finally got round to setting up the circuit above. I was busy last weekend so only managed to get it
done today!. I have also done some fairly thorough testing, as detailed below!
The results of using this circuit are as follows:
Testing with the circuit connected to THE SUPERMID SPEED SENSOR
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Please note : my distance values were a bit rough (I only drove 10 miles), so my values below are in the
correct range, but will probably vary between 5-10% in my final setup, once the SuperMID works!
Circuit A
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This circuit appears to work correctly. Using the 'distance travelled' function on the SuperMID, I can see that
the distance travelled goes up in relation to how far I drive, and if I drive slow or fast, it still increases by the
correct amount.
With my 'distance parameter' set to 2577, I get the following results:
If I drive 1km (in real life), the SuperMID shows 2.682km. This is correct if I drive fast, or slow, and over different
distances.
This means I need to change my 'distance parameter' to 961, in order to get it to work correctly.
When the car is not moving, the distance also stops increasing.
From this test, I can assume that:
-The SuperMID speed sensor circuit appears to work perfectly well with the circuit shown above, and my car's speed sensor. There probably is some background noise which could be 'cleaned up' still.
-I need to set a distance parameter of 961, but, the SuperMID software prevents me from doing that (stopping at the lowest of about 1700), to stop me making mistakes.
Circuit B
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This just does nothing, which is what would be expected, because it is not connected to 12v!.
Testing with the circuit connected to THE SUPERMID INJECTOR SENSOR
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Circuit A
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When driving along......
The 'injector pulse width' shows 0 almost all of the time, but, very occasionally, shows a value between 0.5 and 9.0, which
is completely random.
The 'fuel used' is partly related to speed, as follows:
at 20mph, roughly twice as much fuel is used as at 10mph
at 40mph, roughly twice as much fuel is used as at 20mph
At 40,45,50,55,60,65,70mph, the fuel used remains constant. It is constant at about '10' units (the last two digits on the
fuel use display) per screen update.
When the car is not moving, all the values stop increasing.
Circuit B
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The 'injector pulse width' shows random values most of the time. However, at 60mph, it tends to stay at about 3.5ms, but
does randomly fluctuate between 3 and 5ms, and sometimes shows 0 or 9ms. At 30mph, it tends to stay at about 6-7ms, but again can randomly fluctuate. This is interesting because it seems to have half the pulse width at 60 than it does at 30, which would make sense as the speed sensor circuit is turning twice as fast. That said, there is also a lot of randomness in the reading, and it sometimes goes to 0.00 or 9.00 for a while.
The 'fuel used' behaves in the same way as circuit 'A'
Obviously, it is strange that 'Circuit B' has any readings at all, because it is disconnected from the car 12v supply!
Testing with the circuit connected to MY VOLTMETER
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These tests were done with one voltmeter probe connected to the cars body ground, and the other probe
connected to the speed sensor wire (labelled 'INJ' on the picture above)
These tests were done by parking on an incline, then slowly creeping down the hill, 5cm at a time, and stopping,
to see what the different voltages were.
Circuit A
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There are two possible voltages shown by the circuit : 0.00v, and 11.10v. My battery reads at 12.00v (the engine was
off for this test).
The circuit alternates between 0.00v and 11.10v, maybe every 15-40cm or so (unsure of exact distance). This makes
sense based on how the circuit is set up.
Circuit B
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The voltmeter just reads 0.00v all the time.
If I switch to Circuit A, and then move the car to a position where the speed sensor gives an output of 11.10v, and
switch back to Circuit B, the voltage drops to 0.00v
This makes sense.
SUMMARY
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(1) The SuperMID speed sensor seems to work perfectly with this circuit, but I would need to use a distance parameter of about 960 (maybe even a bit less, e.g. 800, depending on the accuracy of my distance measurements), which SuperMID won't let me set. There may still be background noise with this circuit.
(2) My Voltmeter shows that this circuit is reading between 0.00v, and 11.10v, as expected.
(3) The SuperMID injector sensor seems to behave in a bizarre / random way, but also with some readings that are related to the
speed sensor circuit output, but overall, don't seem to make complete sense.
I would be grateful for any further advice / thoughts / ideas for further experiments, based on these experiments! (I am aware that it is Christmas/New Year now, so things will be a little slower!)
Matt
Linear Mode
