GM SCIAP Breakout Harness for POSITIVE DISPLACEMENT Forced Induction LT1/L83/L86 Vehicles

Wanting better street manners out of your Gen V positive displacement supercharged car or truck? Our SCIAP breakout harness (supercharger inlet pressure sensor) gives your tuner what you need to smooth out sloppy drivability.

With a supercharger there tends to be oscillation/surging in some areas of driving. The ECM doesn’t know you installed a supercharger – so as the bypass valve begins to close, boost comes in and will max out the target torque tables in the ECM. This causes the throttle to close to correct for it. Then the bypass valve opens, dropping MAP and forcing the throttle open again – back and forth, causing oscillations. The overshoot is happening because of the relative vacuum behind the throttle body as boost comes in. Once the supercharger begins to generate a pressure ratio, the desired throttle angle becomes incorrect due to the higher pressure delta across it. The answer is to install and set up a SCIAP breakout harness.

Our SCIAP harness is intended for use on fifth generation ECMs running positive displacement type superchargers such as a Magnacharger or Whipple.

For best results, we set the ECM up like a factory LT4 engine. A LT4 uses 3 pressure sensors instead of the 2 pressure sensors found on non-supercharged engines. This gives the ECM proper pressure data before and after the throttle body so that the blade can be positioned appropriately. Without this kit these superchargers will often have a surge in cruise mainly but also in other driving conditions.

The pressure sensors are Baro, which reads outside ambient air pressure, SCIAP or supercharger inlet pressure which will be located behind the throttle body but before the supercharger, and finally MAP. Which is after the supercharger. SCIAP should not see boost. MAP will.

With any supercharger install you should be installing a non-factory MAP sensor that can read into boost. We will from now on refer to this as the boost reading MAP sensor. Save the original MAP sensor and re-use it for the SCIAP.