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Volumetric Efficiency
A Engine is basically an air pump. Some vehicles have a Mass Airflow Sensor (MAF)
that measures how much air an engine will breathe in. Reading this Sensor
it is possible to determine if your engine is pumping to maximum efficiency. When
Using the Escan's Volumetric Efficiency chart along with The Fuel Trim Chart one
can determine if
Your engine has a breathing issue. Example - plugged converter)
Your MAF Sensor is not reporting correctly.
Your engine has a Fueling Issue.
We would start by doing a volumetric efficiency test.
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In this chart the calculated airflow is much higher than the actual and the boxes
on the right should be green. What this means is that our MAF sensor is reporting
too little airflow compared too what was expected. To decide if it is a problem
with the sensor or the engine we need to look at the Fuel Trim Chart. |
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You can see in this chart that this vehicle has a fueling problem caused by an improperly
functioning MAF sensor. The negative trim values at closed throttle combined with
the Positive values at Wide Open Throttle (WOT) are an indicator of this.
After replacing the MAF sensor the Charts showed significant improvement. This is
just one of the things you can determine with these charts. The next two images
are after the replacement. |
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