Map sensor reading off past 110kpa
04-21-2019, 10:18 PM
#1
Map sensor reading off past 110kpa 2004 GTO LS1 auto
Turbocharged
2 bar factory GM cobalt ss sensor
2 bar custom os
Map sensor linear is set at 210kpa, was as the default 200kpa and same thing. Map sensor offset is default of 10.33kpa
So my map sensor reads off after 110kpa. In my chart, when it starts to wonder off, it reads 110kpa, my afr histogram reads 120kpa. As soon as it hits 115kpa, the histo now says 130kpa. 120.1 it says 140, 125.2 now reads 150.... And so on. The afr kpa is correct because that what my boost controller and boost gauge say. Help me understand what I need to change to make this fall in line, please.
of notable mention. If I log my afr, and I make 12psi (190ish kpa) and I change my fueling in the 180-190-200kpa area, it makes zero difference. To change 190kpa I actually have to change the 150kpa cells because at that point it’s 40 numbers off. So it’s not just in my scanner. Supposedly the settings for map calibration are correct but it’s not reading correct. This is a brand new factory cobalt Ss sensor.
Turbocharged
2 bar factory GM cobalt ss sensor
2 bar custom os
Map sensor linear is set at 210kpa, was as the default 200kpa and same thing. Map sensor offset is default of 10.33kpa
So my map sensor reads off after 110kpa. In my chart, when it starts to wonder off, it reads 110kpa, my afr histogram reads 120kpa. As soon as it hits 115kpa, the histo now says 130kpa. 120.1 it says 140, 125.2 now reads 150.... And so on. The afr kpa is correct because that what my boost controller and boost gauge say. Help me understand what I need to change to make this fall in line, please.
of notable mention. If I log my afr, and I make 12psi (190ish kpa) and I change my fueling in the 180-190-200kpa area, it makes zero difference. To change 190kpa I actually have to change the 150kpa cells because at that point it’s 40 numbers off. So it’s not just in my scanner. Supposedly the settings for map calibration are correct but it’s not reading correct. This is a brand new factory cobalt Ss sensor.
04-21-2019, 11:01 PM
#2
TECH Fanatic
2004 GTO LS1 auto
Turbocharged
2 bar factory GM cobalt ss sensor
2 bar custom os
Map sensor linear is set at 210kpa, was as the default 200kpa and same thing. Map sensor offset is default of 10.33kpa
So my map sensor reads off after 110kpa. In my chart, when it starts to wonder off, it reads 110kpa, my afr histogram reads 120kpa. As soon as it hits 115kpa, the histo now says 130kpa. 120.1 it says 140, 125.2 now reads 150.... And so on. The afr kpa is correct because that what my boost controller and boost gauge say. Help me understand what I need to change to make this fall in line, please.
of notable mention. If I log my afr, and I make 12psi (190ish kpa) and I change my fueling in the 180-190-200kpa area, it makes zero difference. To change 190kpa I actually have to change the 150kpa cells because at that point it’s 40 numbers off. So it’s not just in my scanner. Supposedly the settings for map calibration are correct but it’s not reading correct. This is a brand new factory cobalt Ss sensor.
Turbocharged
2 bar factory GM cobalt ss sensor
2 bar custom os
Map sensor linear is set at 210kpa, was as the default 200kpa and same thing. Map sensor offset is default of 10.33kpa
So my map sensor reads off after 110kpa. In my chart, when it starts to wonder off, it reads 110kpa, my afr histogram reads 120kpa. As soon as it hits 115kpa, the histo now says 130kpa. 120.1 it says 140, 125.2 now reads 150.... And so on. The afr kpa is correct because that what my boost controller and boost gauge say. Help me understand what I need to change to make this fall in line, please.
of notable mention. If I log my afr, and I make 12psi (190ish kpa) and I change my fueling in the 180-190-200kpa area, it makes zero difference. To change 190kpa I actually have to change the 150kpa cells because at that point it’s 40 numbers off. So it’s not just in my scanner. Supposedly the settings for map calibration are correct but it’s not reading correct. This is a brand new factory cobalt Ss sensor.
04-21-2019, 11:37 PM
#3
The default settings in the OS are a start point as I understand them. Between sensors they can vary. What we actually need to know is the voltage produced at min and max MAP, per the sensor, to determine the offset and linear value. I'll take a look into this later and see what I can come up with, but it's clearly a problem with the offset and linear values. Almost every 5v sensor doesn't actually produce 5v. They usually have a range of like 0.4v - 4.65v or so. If the tune is assuming a 5v range, then the numbers will be off for sure. I'll dig around and see I I can pull data for that sensor later. Have to get to work now.
Thanks!
04-22-2019, 12:21 AM
#4
TECH Fanatic
Still digging around for a data sheet, but I did find that a lot of folks use 200 linear and 8 offset. You can give that a try and see if it works. Worth a shot, if not I’ll keep digging in the meantime to confirm it. Problem is with old threads the links to all the data sheets are broke.
04-22-2019, 12:38 AM
#5
TECH Fanatic
In the meantime if you find the data sheet here is the formula to find the numbers. Example is a 3 bar MAP sensor, but the math will work with data for any sensor:
Formula for the data is pretty simple... (P2 - P1) / (V2 - V1) * 5 = Linear Value So (300-20) / (4.65-0.4) * 5 = 329.41
To find range: 329.41 * (4.65/5) = 306.35 total range
Offset is then: 300 - 306.35 = -6.35 kpa offset
Hope that wasn't too complicated. Math works on any sensor you have the data for.
Formula for the data is pretty simple... (P2 - P1) / (V2 - V1) * 5 = Linear Value So (300-20) / (4.65-0.4) * 5 = 329.41
To find range: 329.41 * (4.65/5) = 306.35 total range
Offset is then: 300 - 306.35 = -6.35 kpa offset
Hope that wasn't too complicated. Math works on any sensor you have the data for.
Last edited by ChopperDoc; 04-22-2019 at 12:46 AM.
04-22-2019, 09:07 PM
#6
2004 GTO LS1 auto
Turbocharged
2 bar factory GM cobalt ss sensor
2 bar custom os
Map sensor linear is set at 210kpa, was as the default 200kpa and same thing. Map sensor offset is default of 10.33kpa
So my map sensor reads off after 110kpa. In my chart, when it starts to wonder off, it reads 110kpa, my afr histogram reads 120kpa. As soon as it hits 115kpa, the histo now says 130kpa. 120.1 it says 140, 125.2 now reads 150.... And so on. The afr kpa is correct because that what my boost controller and boost gauge say. Help me understand what I need to change to make this fall in line, please.
of notable mention. If I log my afr, and I make 12psi (190ish kpa) and I change my fueling in the 180-190-200kpa area, it makes zero difference. To change 190kpa I actually have to change the 150kpa cells because at that point it’s 40 numbers off. So it’s not just in my scanner. Supposedly the settings for map calibration are correct but it’s not reading correct. This is a brand new factory cobalt Ss sensor.
Turbocharged
2 bar factory GM cobalt ss sensor
2 bar custom os
Map sensor linear is set at 210kpa, was as the default 200kpa and same thing. Map sensor offset is default of 10.33kpa
So my map sensor reads off after 110kpa. In my chart, when it starts to wonder off, it reads 110kpa, my afr histogram reads 120kpa. As soon as it hits 115kpa, the histo now says 130kpa. 120.1 it says 140, 125.2 now reads 150.... And so on. The afr kpa is correct because that what my boost controller and boost gauge say. Help me understand what I need to change to make this fall in line, please.
of notable mention. If I log my afr, and I make 12psi (190ish kpa) and I change my fueling in the 180-190-200kpa area, it makes zero difference. To change 190kpa I actually have to change the 150kpa cells because at that point it’s 40 numbers off. So it’s not just in my scanner. Supposedly the settings for map calibration are correct but it’s not reading correct. This is a brand new factory cobalt Ss sensor.