Pre-Throttle Boost
Boost pressure measured between the turbo compressor outlet and the throttle body. The turbo's direct output before any throttle restriction.
Why it matters
This is the most accurate measure of turbo performance. Pre-throttle is always slightly higher than MAP at WOT because the throttle body creates a small pressure drop even when fully open.
What to look for
If pre-throttle is high but MAP is low, the throttle body is restricting flow. If pre-throttle is low while WGDC is maxed, the turbo itself can't make pressure, likely a hardware issue.
Related terms
Air pressure measured inside the intake manifold, downstream of the throttle body. This is the pressure the engine actually breathes.
How hard the ECU is working to keep the wastegate closed and maintain boost. 0% = fully open, 100% = fully closed.
The boost pressure the tune is requesting. Actual boost should track this closely.
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