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Boost gauge question??

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Old 04-08-2018, 05:51 AM
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Boost gauge question??

Does anyone know for sure which MAP sensor is used for boost reference?
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Old 04-08-2018, 01:16 PM
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Neither one directly. The ECM has some sort of AlGoreithm to compute it
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Old 04-08-2018, 03:34 PM
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the pressure is measured at one or both of the map sensors. Perhaps it is an average of the two. Although I would like to know for sure.
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Old 04-08-2018, 04:32 PM
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Nothing definitive, but I just disconnected the upper and went for a drive.

Gauge still worked, vacuum down to 20", but would only boost to about 10 PSI. So I think it was still accurate, but boost was limited.

And no CEL.
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Old 04-08-2018, 05:02 PM
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The ECU uses input from the MAF, MAPs, engine speed, ambient temp, intake temp and probably more sensors to calculate the boost and torque. Then it sends a PWM signal to the boost gauge.

You could do what RJ did and disconnect them 1 at a time to see what happens.
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Old 04-08-2018, 05:18 PM
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Originally Posted by RJ_RS_SS_350 View Post
Nothing definitive, but I just disconnected the upper and went for a drive.

Gauge still worked, vacuum down to 20", but would only boost to about 10 PSI. So I think it was still accurate, but boost was limited.

And no CEL.
thanks for doing that. It was very helpful to eliminating t one possible cause of my issue.
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Old 04-08-2018, 05:34 PM
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Originally Posted by evotech View Post
thanks for doing that. It was very helpful to eliminating t one possible cause of my issue.
You could tell us what issues you're having.


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