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Old 06-17-2014, 01:03 PM   #1
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Default Check Engine Light Settings

I am now trying to sensibly set up CEL This is with MS-3 F/W 1.2.4. Next goal is to then use them for Limp Modes.

Question is that, for instance, CLT is set up with ADC values, and all logs I know how to read are in temperature.

What is most straightforward method to correllate, so that I can have CEL come on at say 230F CLT?

And so on for MAT, MAP, etc.
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Old 06-18-2014, 03:22 AM   #2
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Bumping this as i also need the answer to this question
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Old 06-19-2014, 10:07 AM   #3
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The ADC values are meant to correspond to readings that don't just mean overheated, but outright sensor failures. The ADC values are the sensor voltage times 204.8.
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Old 06-19-2014, 10:22 AM   #4
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Maybe a future development could be that the CEL supports both a warning to an out of 'safe' range and also sensor failure.

I.e. flashing when out of range and just on permanently when failed.

Something to suggest to the devs?

EDIT: How do you know the sensor voltage without jury rigging a multimeter up whilst driving? Also, I thought thermisters were measured from their resistance and the voltage was constant?
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Old 06-20-2014, 10:33 AM   #5
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The thermistor behaves that way, but the complete circuit is a voltage divider with a 2.49K resistor in the MegaSquirt to 5V and the sensor going to ground.

So, if you wanted to find the ADC value when the sensor was at 150 ohms:

1. The total resistance of the circuit is going to be 2640 ohms, with 150 ohms to ground.
2. So the voltage would be 5V * (150 ohms / 2640 ohms) = 0.284V.
3. And that would be an ADC count of 58.
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Old 06-26-2014, 02:01 PM   #6
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Reverant, (S/N 12616)
1) Is it necessary for the nitrous1 output to be selected on the CAN for the CEL to light, or is that a possible external light signal?
2) Is the battery light for charging, separate from the CAN CEL for battery voltage?
3) As the battery light is termed "smart" what else might it tell me other than charging?

Matt,
I understand. Not really a temp warning as much as a sensor GOOD / BAD. That explains why TS, which has full understanding of what ADC value means in terms of CLT, is set up for ADC, rather than CLT. Thanks.
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Old 06-26-2014, 07:21 PM   #7
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1) The CEL is on nitrous1 like you said. Nothing to do with CAN.
2) The battery light is completely separate from the MS3 outputs/control.
3) Overcharging (blinking) or not charging (solid on).
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Old 11-14-2016, 08:23 AM   #8
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Quote:
Originally Posted by Matt Cramer View Post
The thermistor behaves that way, but the complete circuit is a voltage divider with a 2.49K resistor in the MegaSquirt to 5V and the sensor going to ground.

So, if you wanted to find the ADC value when the sensor was at 150 ohms:

1. The total resistance of the circuit is going to be 2640 ohms, with 150 ohms to ground.
2. So the voltage would be 5V * (150 ohms / 2640 ohms) = 0.284V.
3. And that would be an ADC count of 58.
Does anyone know the sensor values for the internal MAP sensor from Reverant MS3 Basic ?
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Old 11-14-2016, 11:30 AM   #9
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FWIW I have been trying to get James/Ken to add a limp mode for a while now. Not much interest from them.

The best place to ask these questions is on msextra. The developers are very active and helpful.

Megasquirt Support Forum (MSEXTRA) ? oil pressure/fuel pressure safety (View topic)
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Old 11-14-2016, 11:33 AM   #10
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I spoke too soon. The latest alpha has oil pressure limp mode.

I'll play with it today and see whats up.
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Old 11-14-2016, 02:56 PM   #11
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Oil pressure limp mode? There is some level of safe engine operation when your oil pressure gauge stops working? I would think that an indication of lack of oil pressure, or bad oil pressure readings would call for shutting down the engine.
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Old 11-14-2016, 03:01 PM   #12
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You can read about it on msextra. The basic gist is.

Oil pressure too low, shut down engine (after specified delay)
Oil pressure too high, limp mode (relief valve failure?)
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Old 11-14-2016, 06:18 PM   #13
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Quote:
Originally Posted by etang789 View Post
Does anyone know the sensor values for the internal MAP sensor from Reverant MS3 Basic ?
Select the standard MPX4250AP.
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Old 11-14-2016, 10:30 PM   #14
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To answer your original questions use programmable outputs and loops.
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Old 11-14-2016, 10:42 PM   #15
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Quote:
Originally Posted by Reverant View Post
Select the standard MPX4250AP.
OK got it the ADC values in the Clibrate MAP/Baro is 10 and 260 , correct me if Im wrong.
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