Bradycardia = too slow. A heart rate of less than 60 beats per minute (BPM) in adults is called bradycardia. What's too slow for you may depend on your age and physical condition. Physically active adults (and athletes) often have a resting heart rate slower than 60 BPM but it doesn't cause problems and is normal for them.
Using technology similar to the Jet PCM, the Jet module provides the ultimate in power tuning. Point-by-point air/fuel, ignition advance, transmission, and various other tuning points provide performance gains and, in some cases, improved fuel economy.
Engine Control Unit - Controls only the engine and that is it. Power Train Control Module - Controls the engine, transmission, and other pieces. May still have slave modules that are external to the master module such as the Transmission Control Module for automatic transmissions. The distinction here with PCM is that typically the TCM is useless without the PCM.