LS3 map sensor info

Looking for some info on these. I've heard they were 1.5 bar, I've heard they were 2 bar. Anyone know for sure? I've read where it looks like guys are using them in LS1 style applications. Would this not require a COS?

I've tuned a bunch of LS3 cars, with both softwares, and I'm still not sure myself what they are. Using EFIlive, they don't seem to go to 2 bar on my scanner, but I've been told I didn't have it set up right. No one could tell me what was wrong, just that it wasn't set up right.

:shrug:

TIA

Hey Ed,

The LS3 sensor in the 2010 calibrations has a linear range of something like 128.1kPa with an offset of something like -0.3kPa ( I may be off a bit here).

Unless I am misunderstanding (or there is an unseen parameter), it seems like 128.1kPa should be the 5VDC value reported by the sensor.

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Originally Posted by Frost

Hey Ed,

The LS3 sensor in the 2010 calibrations has a linear range of something like 128.1kPa with an offset of something like -0.3kPa ( I may be off a bit here).

Unless I am misunderstanding (or there is an unseen parameter), it seems like 128.1kPa should be the 5VDC value reported by the sensor.

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That would make sense based on what I've seen in scan data in the later FI Vettes, both LS3 and LS7. Now, with that in mind, using one in a 1 bar OS. You'll obviously have some offset in the tables. Anyone use these with a 1 bar OS? I 'magine it could be fudged, but basically you would be skewing the entire VE.

Thoughts? Anyone done this?

BTW, thanks Steve. Went and looked at an 08 Vette tune, and you're correct on the linear/offset.

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Originally Posted by Frost

The LS3 sensor in the 2010 calibrations has a linear range of something like 128.1kPa with an offset of something like -0.3kPa ( I may be off a bit here).

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Those are the values I got as well, the default on my PCM is 94.43 for linear, 10.33 for offset and 31.48 for linear B

I am trying to use an LS3 MAP sensor on my E40 PCM, I have it wired in and of course it is reporting low on the KPa (83 KPa atmosphere)

The E40 PCM in HPTuners will not let me set a negative number for offset (Is this a limit of the PCM or is this an issue with HPTuners itself?), I set Linear to 128.13, offset to 0 and Linear B to 42.71 since HPTuners says this value should be 1/3 of the Linear value and now the scanner reports 98 KPa atmosphere which is where I would expect it to be but I am unsure of how accurate it is with not being able to set the offset to the proper value.

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Originally Posted by edcmat-l1

That would make sense based on what I've seen in scan data in the later FI Vettes, both LS3 and LS7. Now, with that in mind, using one in a 1 bar OS. You'll obviously have some offset in the tables. Anyone use these with a 1 bar OS? I 'magine it could be fudged, but basically you would be skewing the entire VE.

Thoughts? Anyone done this?

BTW, thanks Steve. Went and looked at an 08 Vette tune, and you're correct on the linear/offset.

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I have had a few LS3 swaps into GenIII cars and had the owners use an LS1 1bar MAP. They all wanted to keep their LS3 MAPs but you can't set the offset and linear in the GenIII cals, not even in the 1bar or MAF Enhanced OS's. Their native 1bar sensor has some positive offset, so the VE will be immediately shifted 'down' by the value of the fixed offset. The VE will be further compressed to the extent that the last 18% or so of the LS3's range will never be reported N/A. Even if the offset issue didn't exist, it would still report 105kPa as being something like 82-84kPa in the 1bar OS.

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Originally Posted by SK360

Those are the values I got as well, the default on my PCM is 94.43 for linear, 10.33 for offset and 31.48 for linear B

I am trying to use an LS3 MAP sensor on my E40 PCM, I have it wired in and of course it is reporting low on the KPa (83 KPa atmosphere)

The E40 PCM in HPTuners will not let me set a negative number for offset (Is this a limit of the PCM or is this an issue with HPTuners itself?), I set Linear to 128.13, offset to 0 and Linear B to 42.71 since HPTuners says this value should be 1/3 of the Linear value and now the scanner reports 98 KPa atmosphere which is where I would expect it to be but I am unsure of how accurate it is with not being able to set the offset to the proper value.

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The offset value is in kPa, so if you can't go below 0, your error is about 0.3kPa and will be linear. IMO, at face value, that sounds acceptable.

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Originally Posted by Frost

The offset value is in kPa, so if you can't go below 0, your error is about 0.3kPa and will be linear. IMO, at face value, that sounds acceptable.

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Unless I'm not thinking about it correctly, this doesn't sound right. If there's a 128Kpa@5v sensor in a 105Kpa OS, then at WOT it will be off 28 Kpa. The 0 Kpa reading may be off .3, but as the Kpa increases (MAP pressure decreases) the difference is a sliding scale. Off 28 Kpa @ WOT, or 14 Kpa @ 50. Right? It won't just be off .3 across the board.

Tell me if my head ain't on write LOL :shrug: :doh:

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Originally Posted by edcmat-l1

Unless I'm not thinking about it correctly, this doesn't sound right. If there's a 128Kpa@5v sensor in a 105Kpa OS, then at WOT it will be off 28 Kpa. The 0 Kpa reading may be off .3, but as the Kpa increases (MAP pressure decreases) the difference is a sliding scale. Off 28 Kpa @ WOT, or 14 Kpa @ 50. Right? It won't just be off .3 across the board.

Tell me if my head ain't on write LOL :shrug: :doh:

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You are right for GenIIIs with a fixed linear and offset. I was talking about his e40 though since he has the ability to setup the linear portion in the calibration. His issue is that it will only accept an offset of 0.0 or greater where it needs to be -0.3kPa.

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Originally Posted by Frost

You are right for GenIIIs with a fixed linear and offset. I was talking about his e40 though since he has the ability to setup the linear portion in the calibration. His issue is that it will only accept an offset of 0.0 or greater where it needs to be -0.3kPa.

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OK. I'm hard headed. I know you can change the linear/offset. What I'm having trouble wit is the KOEO voltage, and how the 128 Kpa map is going to fit with the 105 Kpa table. Maybe I'm over complicating it.

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Originally Posted by edcmat-l1

Maybe I'm over complicating it.

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I think you are Ed :)

What the sensor sees as Atmosphere in KOEO is going to be independent of the PCM... the Sensor is going to output the voltage it is set to at that MAP reading and with the new calibration loaded the PCM should correctly relate that voltage with the correct kPa+0.31 since I don't have access to the E40

I think we will be golden, I will scan my car and a stock LS2 GTO tomorrow to make sure we are within a few tenths of each other.

I am bumping this thread to see if anyone found any ill effects of using a LS3 MAP sensor on the E40. I am in the begining stages of tuning one and do not want to run in to an issue if this is really going to skew my tuning and give me problems that I will be chasing.

-Don

I'm trying to do the opposite use a 105 kpa MAP 09359409 on a 2010 E67, I have it reading 101-102 kpa at key on which sees right, after I scaled it to a 2007 E67 with the same sensor, but I'm still getting code P0108 map high?

AFAIK there is nothing you can do about except set to NO MIL. You can recalibrate the range and offset for the sensor reading as you have done, but that doesnt recalibrate the diagnostic routine which is looking for a low output voltage from the sensor @ 105kpa.

OK, so the 101-102 is normal key on? Will turning off the DTC cause any ill effects? Will it still run fine?

Normal local baro pressure should show at key on. HPT gives you the option of disabling the test or setting DTC's to no MIL or no error reported. Never seen any ill effects.

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Originally Posted by LSX378

Normal local baro pressure should show at key on. HPT gives you the option of disabling the test or setting DTC's to no MIL or no error reported. Never seen any ill effects.

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What's the test to disable? I didn't notice it?

They are at Engine Diags, AIrflow, MAP sensor, right where you set slope and offset. :)