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Boost - What does it mean to a 4.0 xk8?

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Old 09-05-2014, 12:44 PM
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Default Boost - What does it mean to a 4.0 xk8?
I hooked up my OBDII to check my throttle position and saw a -10 Boost.
The throttle position (after adjustment) was 100% but I am wondering what the negative Boost number means.
 
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Old 09-05-2014, 12:55 PM
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Originally Posted by bradstuff
I hooked up my OBDII to check my throttle position and saw a -10 Boost.
The throttle position (after adjustment) was 100% but I am wondering what the negative Boost number means.

It's measuring the vacuum in your intake manifold. Changes with engine speed, etc.



.
 
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Old 09-05-2014, 02:35 PM
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The MAP sensor in these cars is before the S/C so it will never show a positive number.

There isn't a pressure sensor after the S/C so you can't get a real boost measurement over OBD.
 
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Old 09-05-2014, 03:05 PM
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Default Negative Boost Numbers
Thank you - that was informative - at lease it is nothing new to fix!!!
 
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