Common terms, names, and abbreviations you'll come across while reading the Gen2 forums:

CAI: Cold Air Intake. Generally, any after-market air intake filter that replaces the stock air intake box. Often these draw air from inside the engine bay instead of from the duct to the front bumper, so sometimes such designs are derisively called a "hot air intake". On the turbocharged S engines, changing the intake from stock will result in a bit more sound from the engine, but little if any HP gains.

CEL: Check Engine Light, the indicator on your tach that says your car is unhappy about something. Sometimes called MIL, Malfunction Indicator Light. A CEL means there is a code set indicating specific trouble. You can either get a code reader, go to an auto parts store as many will hook up a reader for you, go to the dealer, or an independent mechanic.

DI: Direct Injected, meaning the fuel is injected into the cylinder instead of the intake manifold. The advantages are better fuel economy and reduced emissions. Disadvantages can be carbon build up on the intake valves since there is no fuel passing over the valve to keep it clean.

ECU: Engine Control Unit, the computer that runs the engine. Also sometimes referred to as DME: Digital Motor Electronics (BMW terminology), or PCM: Powertrain Control Module.

FMIC: Front Mounted Intercooler. The heat exchanger located beneath the front bumper that cools the air coming out of the turbo before it goes to the intake manifold.

HPFP: High Pressure Fuel Pump. The pump that provides the pressure required for Direct Injection engines. A common failure point on the N14 and early N18 engines.

IAT: Intake Air Temperature. The purpose of the FMIC is to reduce the IAT, which means denser air and therefore more power.

MAF: Mass Air Flow sensor, measures air flow into the engine. Sometimes the MAF is referred to as a “HFM” or hot film mass air sensor.

MAP: Manifold Absolute Pressure sensor, measures vacuum/boost in the intake manifold.

OCC: Oil Catch Can. A device inserted into the PCV connection to the intake manifold, intended to remove oil from the vapor and reduce carbon build up on the intake valves.

PCV: Positive Crankcase Ventilation. This is an important pollution control mechanism on all modern engines. Pressure builds up in the crankcase from combustion leaking past the piston rings, or "blow-by." This pressure needs to go somewhere, since it is full of hydrocarbons to prevent pollution it is routed back to the intake manifold and burned in the engine. See OCC and DI above.

RSB: Rear Sway Bar. One of the most popular upgrades to the handing of the Gen2 Minis is to replace the stock RSB with a stiffer version.

STFT and LTFT- short term fuel trim and long term fuel trim. Adjustments in amount fuel delivered primarily based on upstream wideband o2 sensor. Short term makes quick adjustments and long term takes more time to change.

TSB: Technical Service Bulletin, an official communication from the factory to dealers about specific issues. See the Information Sources thread in the FAQ about where to find these.

Valvetronic is BMW's name for the variable valve lift system on the N18 engine.

VANOS is what BMW calls the variable valve timing system, it changes the timing of .the camshaft relative to the crankshaft. N14 engines have "single Vanos" which is variable valve timing on the intake camshaft. N18 engines have "dual Vanos" which is variable timing on both intake and exhaust camshafts, as well as Valvetronic variable valve lift.

WMI: Water/Meth Injection. Useful to prevent early detonation when running high boost.

Add suggestions for abbreviations and their definitions and I'll add them to this list.

 

Updated the list and deleted the now redundant posts. Thanks for all the suggestions!