TPI MAP Sensor Function
Thread Starter
Drifting
Joined: Jun 2018
Posts: 1,678
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From: Michigan
TPI MAP Sensor Function
Who has deep dove into MAP sensors.
Started tuning my 88 and have a Code 33. Not too concerned as I just turned it on for the first time with EBL MAP conversion. However, to troubleshoot what is going on, I would like to understand a few things better.
There is a Flag in the .Bin that allows me to select 1,2 or 3 bar MAP. This is a no brainier, 1 for NA, 2 Bar up to 15PSI of boost, 3 Bar up to 30PSI of boost.
I have not had time to experiment with different MAPs and I don't see a calibration table or chart in the .XDF. What I did find was Code 33 had a different threshold voltage depending on selection.
Does the 1Bar, 2Bar, and 3Bar have the same voltage reading for say 50KPa? It appears Higher pressure = Higher Voltage. So does the 1Bar only send so much Voltage or does the 1 Bar, 2Bar, and 3Bar all work on the same voltage scale with different pressure interpreted at the computer based on selection.
If it matters, I am using MAP sensor #213-1520, GM#1256941
Started tuning my 88 and have a Code 33. Not too concerned as I just turned it on for the first time with EBL MAP conversion. However, to troubleshoot what is going on, I would like to understand a few things better.
There is a Flag in the .Bin that allows me to select 1,2 or 3 bar MAP. This is a no brainier, 1 for NA, 2 Bar up to 15PSI of boost, 3 Bar up to 30PSI of boost.
I have not had time to experiment with different MAPs and I don't see a calibration table or chart in the .XDF. What I did find was Code 33 had a different threshold voltage depending on selection.
Does the 1Bar, 2Bar, and 3Bar have the same voltage reading for say 50KPa? It appears Higher pressure = Higher Voltage. So does the 1Bar only send so much Voltage or does the 1 Bar, 2Bar, and 3Bar all work on the same voltage scale with different pressure interpreted at the computer based on selection.
If it matters, I am using MAP sensor #213-1520, GM#1256941
Last edited by KyleF; Jul 13, 2020 at 03:41 PM.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
As your chart notes, all three sensors sweep their full pressure range with a zero to five volts output signal, as 5V is the supply voltage powering the sensor, and the same 5V is used as the reference voltage for the A/D circuit in the ECM/PCM.
Thread Starter
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
Yup, and it looks like what I am seeing in my display is now the N-Alpha value that is selected if Code33 is present. What is great is since the system was built on 1Bar, the values are skewed. I am using the tables for a 2bar since I am supercharged. Well, it is telling my car that it is under 12PSI of boost at idle.
I have some work to do to get to the root of the issue, but at least now I know how the MAP system works. I had always had MAF cars previously... btw, this is and L98 in an IROC, but applicable to the TPI Vettes.
I have some work to do to get to the root of the issue, but at least now I know how the MAP system works. I had always had MAF cars previously... btw, this is and L98 in an IROC, but applicable to the TPI Vettes.
Last edited by KyleF; Jul 15, 2020 at 05:38 PM.
