Adding Oil Pressure and Oil Temp on an MS2pnp
09-17-2024 | 08:14 PM
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Adding Oil Pressure and Oil Temp on an MS2pnp
I struggled to find a concise source of all this info, so now that I have it all working I'd figure I'd throw a post together to hopefully help some people out because I know I would have wanted something like this. I did this on my boosted 1995 on an MS2pnp but from my understanding, this should work on any MS2pnp, but I can't speak for other types of MS2's.
Sensors:
For pressure im just using this I found on Amazon but any 0-5v linear sensor with the appropriate pressure rating should do as long as they have published calibration values.
For temperature im using a coolant temp sensor off an old Saturn. From my understanding, this is one of the only sensors that uses the GM curve that's 1/8npt and reasonably priced.
Wiring:
The MS2pnp has 2 "spare" analog inputs one of which can be accessed via the options port but not by default. On the PCB they are referred to as ADC1 and ADC2 and in Tuner Studio they are ADC6 and ADC7 respectively. ADC1 is usually used for an external MAP sensor and ADC2 is usually used for the knock sensor input so if you are using either of those you can't use them as a sensor input of course. To access ADC1 from your options port you will have to open up your MegaSquirt and pull the left jumper on jumper 15, you can pull both if you intend to use ADC2 as well. Then run a wire from the pin labeled ADC1 to the pin on jumper 17 labeled EXT. This will allow you to access ADC1 from 19.External MAP sensor input on your options port. For ADC2 pull the right jumper on jumper 15 and unfortunately, there is no way to route this into your options port as far as im aware. I just drilled a hole in my case next to the options port being careful not to let any metal chips go where they shouldn't and ran a wire from the ADC2 pin out of the case. I guess you could also use an unused wire if you have any on the chassis harness plug.
To wire in the pressure sensor you just need to give it 5Vref and sensor ground from your options port and the signal wire goes to one of your new ADC inputs. For the temp sensor, one wire goes to sensor ground, and the other to your desired ADC pin. You'll also need a 2.49k pullup resistor between the ADC pin and 5Vref this is the standard for GM sensors. I didn't have a 2.49k resistor on hand and I didn't want to wait for one so I just put a 2.7k and 33k resistor in parallel and that got me close enough. I cut off the connector housing around the pins and soldered some wires to go to a DTM plug but the pigtail for the sensor can be found here as well.
Tuner Studio Setup:
In Tuner Studio to add your new sensors you'll use the "Add Custom Channel Wizzard" under the Tools tab at the top of the window. Here you can choose the input channel (ADC6 or ADC7) as well as name your channel(no spaces) and choose the units. For the pressure sensor you can just plug in the values given for your sensor. For the temp sensor since its non linear you'll have to upload a custom inc file. Here's a link to one for GM style sensors. In the next window you'll add your gauge template and data log field, I have not figured out how to change these after the fact without fully deleting the channel and going through this process again. Not a huge deal but try and make sure you have everything here right. All of these fields are well explained with the little blue question marks. I would keep the name of the channel from the last screen and the gauge and log field name the same, as well as put it under the "Sensor inputs 1" category. After that, you should be able to select one of your new fields as an input for a gauge and will also show up in data log files. Hooray!
Sensors:
For pressure im just using this I found on Amazon but any 0-5v linear sensor with the appropriate pressure rating should do as long as they have published calibration values.
For temperature im using a coolant temp sensor off an old Saturn. From my understanding, this is one of the only sensors that uses the GM curve that's 1/8npt and reasonably priced.
Wiring:
The MS2pnp has 2 "spare" analog inputs one of which can be accessed via the options port but not by default. On the PCB they are referred to as ADC1 and ADC2 and in Tuner Studio they are ADC6 and ADC7 respectively. ADC1 is usually used for an external MAP sensor and ADC2 is usually used for the knock sensor input so if you are using either of those you can't use them as a sensor input of course. To access ADC1 from your options port you will have to open up your MegaSquirt and pull the left jumper on jumper 15, you can pull both if you intend to use ADC2 as well. Then run a wire from the pin labeled ADC1 to the pin on jumper 17 labeled EXT. This will allow you to access ADC1 from 19.External MAP sensor input on your options port. For ADC2 pull the right jumper on jumper 15 and unfortunately, there is no way to route this into your options port as far as im aware. I just drilled a hole in my case next to the options port being careful not to let any metal chips go where they shouldn't and ran a wire from the ADC2 pin out of the case. I guess you could also use an unused wire if you have any on the chassis harness plug.
To wire in the pressure sensor you just need to give it 5Vref and sensor ground from your options port and the signal wire goes to one of your new ADC inputs. For the temp sensor, one wire goes to sensor ground, and the other to your desired ADC pin. You'll also need a 2.49k pullup resistor between the ADC pin and 5Vref this is the standard for GM sensors. I didn't have a 2.49k resistor on hand and I didn't want to wait for one so I just put a 2.7k and 33k resistor in parallel and that got me close enough. I cut off the connector housing around the pins and soldered some wires to go to a DTM plug but the pigtail for the sensor can be found here as well.
Tuner Studio Setup:
In Tuner Studio to add your new sensors you'll use the "Add Custom Channel Wizzard" under the Tools tab at the top of the window. Here you can choose the input channel (ADC6 or ADC7) as well as name your channel(no spaces) and choose the units. For the pressure sensor you can just plug in the values given for your sensor. For the temp sensor since its non linear you'll have to upload a custom inc file. Here's a link to one for GM style sensors. In the next window you'll add your gauge template and data log field, I have not figured out how to change these after the fact without fully deleting the channel and going through this process again. Not a huge deal but try and make sure you have everything here right. All of these fields are well explained with the little blue question marks. I would keep the name of the channel from the last screen and the gauge and log field name the same, as well as put it under the "Sensor inputs 1" category. After that, you should be able to select one of your new fields as an input for a gauge and will also show up in data log files. Hooray!
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