Interceptor gauge issue with boost

On my cousins GT500 (2011) we installed a single interceptor gauge and then added the 3.5 bar map sensor. After getting it set up as per the instructions it only shows 5psi. Anyone else run into this issue ? I did this same install but on my 03 and I have no issues. I know my cousins reached out to aeroforce and they told him to move the ground and the power wire to a different fuse and it didn’t change anything.


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What port are you using for boost?

Catmonkey said:

What port are you using for boost?

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Vacuum line comes off the map sensor and it tied into a line on the fuel rail.


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was it set up correctly in the gauge? IE does it show 0 with the engine off and vacuum seems correct @ idle?

I'd verify you entered the slope and interceptor values correctly and that the slope has the negative sign entered. Other than that, I have nothing.

DSG2003Mach1 said:

was it set up correctly in the gauge? IE does it show 0 with the engine off and vacuum seems correct @ idle?

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I’ll double check it later when I see my cousin. I know Initially it read -55.5 and I had him change the ground.


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Catmonkey said:

I'd verify you entered the slope and interceptor values correctly and that the slope has the negative sign entered. Other than that, I have nothing.

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When I see him later I’m going to double check it but I know when we first hooked it up I entered the slope and intercept in. The gauge read -55.5 initially. Then he changed the ground to a different location and it stopped reading -55.5


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blwn89gt said:

I’ll double check it later when I see my cousin. I know Initially it read -55.5 and I had him change the ground.


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as mentioned above if it's not reading 0 engine on, key off and correct vacuum at idle Id be looking at the slope/intercept as it's real easy to screw that up on these things

DSG2003Mach1 said:

as mentioned above if it's not reading 0 engine on, key off and correct vacuum at idle Id be looking at the slope/intercept as it's real easy to screw that up on these things

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I’ll double check it but I know I entered the slope and intercept correctly because I did it on my own gauge in my cobra and mine works fine.


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Wound up trying the map sensor out of the cobra in it and still didn’t work. Got in touch with aeroforce and sent them the map sensor and gauge. Aeroforce had me set the intercept / slope to read volts and it was getting half of what aeroforce said it should have.


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Have you checked your battery and alternator voltage? All sorts of weird stuff happens on these 5 volt senors systems when voltage isn't where it should be. Take a reading at their 5 volt power supply and see how much voltage you're getting there.

Catmonkey said:

Have you checked your battery and alternator voltage? All sorts of weird stuff happens on these 5 volt senors systems when voltage isn't where it should be. Take a reading at their 5 volt power supply and see how much voltage you're getting there.

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I will check that out. Thank you


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Sent the sensor and gauge back to aeroforce, they tested it and said it’s good and gave me a new map sensor also. Put it back in and still have the same issue. This is so frustrating.


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If you are using aeroforce 3.5 bar maps sensor it's meant to work off 12 volts and not 5 volts. I know there is talk of 5v for other sensors on the site but that specific 3.5 bar sensor is meant for 12v power. It's been a while since I did mine but IIRC it was red wire to 12v key on from the fuse box, black wire to ground stud near the fuse box and white wire is signal and run through fire wall and plugs into analog gauge port. So if you are only feeding the sensor 5v that could explain the issue.

merkyworks said:

If you are using aeroforce 3.5 bar maps sensor it's meant to work off 12 volts and not 5 volts. I know there is talk of 5v for other sensors on the site but that specific 3.5 bar sensor is meant for 12v power. It's been a while since I did mine but IIRC it was red wire to 12v key on from the fuse box, black wire to ground stud near the fuse box and white wire is signal and run through fire wall and plugs into analog gauge port. So if you are only feeding the sensor 5v that could explain the issue.

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It’s hooked up to a 12v key on from the fuse box.


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Try putting his in your car this time. If it does then obviously something is ****y in the wiring

So lets just make sure we have the following;

-Map sensor
red wire - 12v key on
black wire - ground
white wire - sensor signal and run into car

-Gauge
OBD2 plug - plugged into bottom port of gauge
Analog gauge pins - Looking at back of gauge analog 2 is the top left pin and analog 1 is the top right pin
Analog plug - Analog 2 = White wire / Analog 1 = Green wire
The white wire from the map sensor will be connected to the white wire of the analog plug. You will NOT use the green or red wire of the analog plug, tape off each wire and to avoid any possible shorts.

-Check vacuum hose connection for any leaks between map sensor and where you tee'd into.
-Make sure gauge is set to use analog input 2 and the slope values are set correctly.
-You should have 0 psi with engine off and key in run position.
-With engine running you should be seeing around -11 to -9 psi

If all of this is checked and correct then put a mechanical gauge on the car and confirm the SC is really pushing out more than 5 psi, maybe you just have belt slip or something.

Per the 3.5 bar MAP sensor kit instructions for part # Sens022, at or close to sea level, slope is 014.0 and intercept is -14.0. These are the values I use.

The Interceptor user manual instructions for setting up Analog 1 (or 2) are misleading. It states as an example for a GM 3 bar MAP to use slope 009.2 and intercept -14.7

SCGallo2 said:

Per the 3.5 bar MAP sensor kit instructions for part # Sens022, at or close to sea level, slope is 014.0 and intercept is -14.0. These are the values I use.

The Interceptor user manual instructions for setting up Analog 1 (or 2) are misleading. It states as an example for a GM 3 bar MAP to use slope 009.2 and intercept -14.7

Click to expand...

I used the 014.0 and 14.0 I’m going to try to get out later this week and mess with it.


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Update so far. Got outside and re wired the gauge in with the same results of only reading 5psi. Put a mechanical gauge on and it’s reading the same so the aeroforce gauge is reading correctly, however the culprit is most likely the boost bypass valve after testing it. I’m calling vmp Monday, I have the low vacuum bypass valve on the car from them.


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