GM 3 BAR MAP SENSOR

[JulianSerna]

Hi, I have installed GM 3 BAR MAP Sensor (P/N 12223861). I have selected the proper sensor via the Sensors Wizard. I have also selected PSI for Configure-->Units-->Load Units=PSI. However, when I look at the Fuel Map Table, I only see breakpoints from -14.40 to + 9.44 range and I know that this sensor can read up to 30 lbs of boost. My question is, why doesn't the Map Table give me a Y axis rage from -14.40 to + 30, the whole range of my MAP sensor?

Thanks.

[toyman]

Hi, I have installed GM 3 BAR MAP Sensor (P/N 12223861). I have selected the proper sensor via the Sensors Wizard. I have also selected PSI for Configure-->Units-->Load Units=PSI. However, when I look at the Fuel Map Table, I only see breakpoints from -14.40 to + 9.44 range and I know that this sensor can read up to 30 lbs of boost. My question is, why doesn't the Map Table give me a Y axis rage from -14.40 to + 30, the whole range of my MAP sensor?

Thanks.

Not 100% certain but I believe you set the breakpoint range. You would want to do this so the scale is related to the boost you are producing.  It's my understanding this will give you better resolution for the cells that are relevant to your application. If you had a different MAP sensor before the scale range should be the same.

[JulianSerna]

Thanks, I finally got the car running. I started out with the AEM 2BAR 19 PPH calibration and just modified the fuel table by right-clicking on any cell in the fuel map table and selecting "Change injector/pressure" popup menu. I went from the original 19 PPH to my current 60 PPH injectors @ 40 PSI fuel pressure and the car finally started.

However, even though the car runs, I noticed that the PSI reading on the Y axis of the fuel map table is way off when compared to the PSI reading on my dashboard gauge. I did select the correct GM 3-Bar Manifold Pressure Sensor using the sensor wizard ( part #12223861), I did not need to modify the load breakpoints as I have not installed my turbos yet, so the default max psi of 8 on the load table is fine. But why are the readings completly off?

Thanks.

[toyman]

Thanks, I finally got the car running. I started out with the AEM 2BAR 19 PPH calibration and just modified the fuel table by right-clicking on any cell in the fuel map table and selecting "Change injector/pressure" popup menu. I went from the original 19 PPH to my current 60 PPH injectors @ 40 PSI fuel pressure and the car finally started.

However, even though the car runs, I noticed that the PSI reading on the Y axis of the fuel map table is way off when compared to the PSI reading on my dashboard gauge. I did select the correct GM 3-Bar Manifold Pressure Sensor using the sensor wizard ( part #12223861), I did not need to modify the load breakpoints as I have not installed my turbos yet, so the default max psi of 8 on the load table is fine. But why are the readings completly off?

Thanks.

If I understand you correctly there is no boost, so WOT will be 0 PSig. Your gauge in vacuum is reading inHg NOT -PSig. It's a different scale. So, if at idle the gauge reads 20 inHg the MAP will read about -9PSig. Is this the difference you are talking about?

[JulianSerna]

Yes, toyman, that is correct, there should be 0 vacuum at WOT. However,  I went to Configure, Units, Load Units and changed from the default inHg to PSI. Now my Fuel Map table reads in PSI.

From what I can gather, my Fuel Map table should now read close to the dashboard gauge readout, but it is totally off. It is as if the Y-Axis load points were just arbitrately there for tuning purposes and had nothing to do with the specific MAP sensor selection. In other words, it mind as well be rows with any desending, assigned numbers (top row = 16 and bottom row = 0, perhaps to express load).

I know the sensor is working properly because when I re-install the PMS module I had before, the load perfectly matches the gauge readout.

I am confused and would appreciate any help. Thanks for your reply, toyman.        

[toyman]

Yes, toyman, that is correct, there should be 0 vacuum at WOT. However,  I went to Configure, Units, Load Units and changed from the default inHg to PSI. Now my Fuel Map table reads in PSI.

From what I can gather, my Fuel Map table should now read close to the dashboard gauge readout, but it is totally off. It is as if the Y-Axis load points were just arbitrately there for tuning purposes and had nothing to do with the specific MAP sensor selection. In other words, it mind as well be rows with any desending, assigned numbers (top row = 16 and bottom row = 0, perhaps to express load).

I know the sensor is working properly because when I re-install the PMS module I had before, the load perfectly matches the gauge readout.

I am confused and would appreciate any help. Thanks for your reply, toyman.        

The penny just dropped. Are you referring to the dashboard screen in AEMPro and the boost gauge on the dashboard screen or are you talking about a regular boost gauge? I think it's the latter. If you are referring to a regular boost gauge then below 0 will usually be in inHg and above 0 in psi. Load the tuning menu screenon your laptop and follow the engine load vs your gauge. Other than the different scale below 0 the readings should match once you have adjusted for the different between ihHg and psi.

[JulianSerna]

I feel so silly ... I had nevered looked close enough at my boost gauge to notice that boost is measured in PSI and vacuum in "inHg". I thought  these gauges were so simple that they could not possibly have 2 different measurements. I guess you live and you learn (I must take a closer look at my wife tonight to see if I notice something new about her which I am failing to see everyday).

Thanks toyman!