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Sharing oem sensors
Posted: Sun Nov 15, 2009 3:33 am
by warp21
Can the Microsquirt module share oem temperature sensors with the factory ecu? It looks like I'd have to lift R7 and R10.
Re: Sharing oem sensors
Posted: Tue Nov 17, 2009 9:19 am
by Matt Cramer
Depends on how exactly the factory ECU behaves. I take it you've seen this link:
http://www.megamanual.com/v22manual/sharesen.htm
Re: Sharing oem sensors
Posted: Sat Nov 21, 2009 3:34 am
by warp21
Yes I have. I've done it with the MSII PCB 3.0 and it worked fine. I didn't know if there was a way other than removing the resistors.
Re: Sharing oem sensors
Posted: Mon Nov 23, 2009 5:29 am
by warp21
I have one more question. Would it be possible to share the factory map sensor signal assuming that I could get accurate kpa vs voltage values?
Re: Sharing oem sensors
Posted: Mon Nov 23, 2009 10:37 am
by Matt Cramer
warp21 wrote:Yes I have. I've done it with the MSII PCB 3.0 and it worked fine. I didn't know if there was a way other than removing the resistors.
You could possibly do something with an op amp and a voltage follower circuit as well.
warp21 wrote:I have one more question. Would it be possible to share the factory map sensor signal assuming that I could get accurate kpa vs voltage values?
As long as it's voltage based and not frequency based, yes.
Re: Sharing oem sensors
Posted: Tue Nov 24, 2009 7:37 am
by warp21
Does this look like correct? If so do I calibrate the sensors just as if the factory ecu was not there?
Re: Sharing oem sensors
Posted: Tue Nov 24, 2009 8:11 am
by Matt Cramer
That's about what I had in mind.
Re: Sharing oem sensors
Posted: Tue Nov 24, 2009 9:02 am
by warp21
Awesome, Thanks! I really didn't want to lift a surface mount resistor.
Re: Sharing oem sensors
Posted: Sun Dec 06, 2009 5:06 am
by warp21
I used this on a spare MS I to test the accuracy of the circuit. I have a factory ecu with two of these LM741 circuits, one tied to the coolant sensor and one to the intake sensor. The MS is calibrated to work with the oem sensors and seems accurate. If I have the MS hooked to the sensors by itself the readings look OK but once I tap into the op amp output they read really low. I'm using the 5v from the factory ecu to power the op amp. Should I be using the 5v from the MS?
Re: Sharing oem sensors
Posted: Mon Dec 07, 2009 9:54 am
by Matt Cramer
warp21 wrote:I used this on a spare MS I to test the accuracy of the circuit. I have a factory ecu with two of these LM741 circuits, one tied to the coolant sensor and one to the intake sensor. The MS is calibrated to work with the oem sensors and seems accurate. If I have the MS hooked to the sensors by itself the readings look OK but once I tap into the op amp output they read really low. I'm using the 5v from the factory ecu to power the op amp. Should I be using the 5v from the MS?
I'd definitely use the MS 5 volt. Is the voltage different on the input and output of the op amp?