Electronic boost gauge project
06 February 2002, 11:06 AM
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I am thinking about building a Electronic boost gauge (similar to the AFR one) and need some information.
1) Where is the MAP sensor located on a MY96
2) Which pin does the signal connect to the ECU on (and wire colour)
3) What is the range and output signal voltage levels from it
According to the Link manual (for a MK5) it has a maximum reading of 240Kpa (absolute) = approx. 140Kpa max boost reading or 1.4 bar, but I need to know it’s full range, I presume it would be 0 – 240Kpa = -1 to + 1.4 Bar. I also would need to know if it was a linear or logarithmic scale. And also if the MY96 has the same sensor as the later models.
HELP
Stuart
1) Where is the MAP sensor located on a MY96
2) Which pin does the signal connect to the ECU on (and wire colour)
3) What is the range and output signal voltage levels from it
According to the Link manual (for a MK5) it has a maximum reading of 240Kpa (absolute) = approx. 140Kpa max boost reading or 1.4 bar, but I need to know it’s full range, I presume it would be 0 – 240Kpa = -1 to + 1.4 Bar. I also would need to know if it was a linear or logarithmic scale. And also if the MY96 has the same sensor as the later models.
HELP
Stuart
06 February 2002, 01:05 PM
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Don't know about your MY, others may chip in, but the ravensblade site may be useful, as will Link manuals.
On MY99/00 the MAP sensor shows 2.29V with engine off, +1.8 bar at 4.84V, -1.0 bar at 0.88V (relative pressures given). These were from Bob Rawle and they correlate well with my findings and also those in the DIY FCD thread.
The output is linear in a sensible range, and I use it for my boost controller and it works well.
You may want to think about cascading LM3914N chips and displays together as per the data sheet link in the AFR meter thread to get more than 10 LEDs.
The alternative is to use a microcontroller with ADC and output to an LCD display as a number and or a graph. You could also use a DAC (+RPM input if you want) to remap your MAP sensor to give a different boost profile if you are using the ECU for boost control.
A 10 segment display in 0.5PSI intervals around your desired boost target may be useful.
The input impedance of the LM3914N or you average op amp or microcontroller is perfectly high enough not to alter the readings from the sensor.
Let me know if I can help any more.
On MY99/00 the MAP sensor shows 2.29V with engine off, +1.8 bar at 4.84V, -1.0 bar at 0.88V (relative pressures given). These were from Bob Rawle and they correlate well with my findings and also those in the DIY FCD thread.
The output is linear in a sensible range, and I use it for my boost controller and it works well.
You may want to think about cascading LM3914N chips and displays together as per the data sheet link in the AFR meter thread to get more than 10 LEDs.
The alternative is to use a microcontroller with ADC and output to an LCD display as a number and or a graph. You could also use a DAC (+RPM input if you want) to remap your MAP sensor to give a different boost profile if you are using the ECU for boost control.
A 10 segment display in 0.5PSI intervals around your desired boost target may be useful.
The input impedance of the LM3914N or you average op amp or microcontroller is perfectly high enough not to alter the readings from the sensor.
Let me know if I can help any more.
02 June 2002, 01:15 PM
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Cheers John, I'm just looking at the Link manual for a MY96 now.
Initially I am planning just to cascade LM3914 IC's to either a bargraph type LED display or individual LED's in a nice semi circle, probably every 1 PSI or so until about 11 PSI then every 0.5 PSI after that
Do you have a URL for the Ravensblade site ??
Stuart
[Edited by sasim - 2/6/2002 1:23:24 PM]
Initially I am planning just to cascade LM3914 IC's to either a bargraph type LED display or individual LED's in a nice semi circle, probably every 1 PSI or so until about 11 PSI then every 0.5 PSI after that
Do you have a URL for the Ravensblade site ??
Stuart
[Edited by sasim - 2/6/2002 1:23:24 PM]
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