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3 BAR MAP Giving me 109 kpa at idle

Old 01-05-2019, 05:51 PM
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Default 3 BAR MAP Giving me 109 kpa at idle

Just installed an EFI Source 3 Bar MAP. Flashed PCM to 3 Bar OS using the linear of 305 and offset of 10.33

With the engine idling, if I pull the sensor out of the manifold (the sensor will not give me a reading it I just do key on.. engine has to be running) HPTuners scanner (logging 3 Bar MAP PID) shows me 109 Kpa

Atmospheric pressure in Houston right now is 101.5597 kpa.. 109 kpa to 101.6 kpa is a difference of about 1 psi

Anyone know if I should mess with the linear and offset? Or just leave it as is?

Anyway I can get it to read exactly correct?
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Old 01-06-2019, 12:15 AM
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Originally Posted by TXjeepTJ View Post
Just installed an EFI Source 3 Bar MAP. Flashed PCM to 3 Bar OS using the linear of 305 and offset of 10.33

With the engine idling, if I pull the sensor out of the manifold (the sensor will not give me a reading it I just do key on.. engine has to be running) HPTuners scanner (logging 3 Bar MAP PID) shows me 109 Kpa

Atmospheric pressure in Houston right now is 101.5597 kpa.. 109 kpa to 101.6 kpa is a difference of about 1 psi

Anyone know if I should mess with the linear and offset? Or just leave it as is?

Anyway I can get it to read exactly correct?

I don't understand. You say the sensor does not give a reading, but then you say what the sensor reads?
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Old 01-06-2019, 11:52 AM
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engine idling it should read like 40-50 kPa

KOEO is should read ambient baro aka 101 kPa at sea-ish level
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Old 01-06-2019, 05:13 PM
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Originally Posted by gametech View Post
I don't understand. You say the sensor does not give a reading, but then you say what the sensor reads?
The sensor doesn’t give a reading with key on engine off. Only will show me a reading when the engine is actually running
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Old 01-06-2019, 05:15 PM
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Originally Posted by truckdoug View Post
engine idling it should read like 40-50 kPa

KOEO is should read ambient baro aka 101 kPa at sea-ish level
Key on engine off it won’t give me a reading

if I pull the sensor while the engine is running (same as key on engine off, since the sensor is out of the intake) I get 109kpa which is decently off from right.

Wondering if I mess with the offset I can get it to read right
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Old 01-06-2019, 05:36 PM
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Did EFI Source give you the parameters for the sensor? Are those the right ones?

My DPE 2.5 Bar, they gave me the offset and linear...
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Old 01-06-2019, 07:04 PM
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do any of your sensors read at KOEO?

but yeah usually you subtract or add offset until it reads 101kPa as ambient baro at sea level
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Old 01-07-2019, 12:27 AM
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y-y1=(y2-y1/x2-x1)(x-x1)

Offset linear can be found with above formula or simply laid out y=mx+b

I've had instances where KOEO the 3 bar map pid does not read, its a OS glitch. I suggest adjust the offset.
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Old 01-07-2019, 08:53 AM
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Originally Posted by subeone View Post
y-y1=(y2-y1/x2-x1)(x-x1)

Offset linear can be found with above formula or simply laid out y=mx+b

I've had instances where KOEO the 3 bar map pid does not read, its a OS glitch. I suggest adjust the offset.
Yup, reading through HPTuners posts, one of the actual programmers posted that it WILL read 0 KOEO.. annoying glitch lol

Thanks!!!!
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Old 01-07-2019, 09:19 AM
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Make sure your 3 bar OS applied correct (you did a write entire, not just write calibration).
Also, double check your MAP sensor. A 1 bar MAP on a 3 bar OS will read around 100 KPA while idling.
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Old 01-08-2019, 10:19 AM
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I hate those junk chinese sensors
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Old 01-08-2019, 11:52 AM
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2 Bar / 3 Bar MAP sensors with Custom OS don't give a reading at KOEO (it will show 0 in the scanner), the engine must be running to give a reading.
What I do is start the engine then use bi-directional controls in the scanner to kill the engine without closing ignition. This way it will keep reading MAP then you can check if it matches BARO
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