MAP — 3-bar GM

Manifold absolute pressure · sensor · Pressure

0–5 V absolute-pressure sensor. Default Race Core MAP is Analog Volt 1. A 3-bar (GM 12223861 family) covers NA through ~2 bar of boost. 1-bar and 2-bar parts share the pinout and need a different calibration.

Typical parts: GM / Delphi 12223861 3-bar; GM 16040749; MSD 2313

Warning — Do not use power ground. MAP return is sensor ground on connector C. A block-strap return puts starter current in the MAP trace and looks like a random lean.

Device pinout

Looking into the sensor, locking tab at the top. Pins A · B · C left to right.

• Connector: Delphi / weatherpack 3-way on the sensor
• Layout (looking into the part): A · B · C; polarising key top

Wiring notes

• GM 1 / 2 / 3-bar brick sensors share this pinout. Identify the stamp (749 / 861 = 3-bar) and set the calibration in TunerStudio — a 1-bar cal on a 3-bar sensor reads ~1/3 of real pressure.
• Key-on, engine-off MAP must agree with local atmospheric pressure (~100 kPa at sea level, mid-80s in Johannesburg).
• Hose to a dry manifold takeoff, not the fuel-pressure regulator tee. A wet hose reads boost late and dribbles fuel into the sensor.
• Gen IV LS MAP on the intake is a different connector. Same three functions; confirm A/B/C on that housing before you crimp.

Failure modes

• Key-on MAP near 0 V or 5 V: signal open, or 5 V shorted to the signal pin.
• Key-on MAP far from local atmospheric pressure: the calibration is for a different bar range. A 1-bar curve on a 3-bar sensor reads about a third of the truth.
• MAP jumps when the starter engages: the return is on power ground. Move it to sensor ground.
• Boost arrives late in the log: the hose is long, wet, or teed into the fuel-pressure reference.

See also

• Bosch P+T — a different sensor. Do not use the MAP calibration on a fluid sender.