Multi-stage turbocharger system

A method of operating a turbocharged internal combustion engine which includes:

• a first relatively small turbocharger including a first exhaust turbine situated in a first exhaust passage from the internal combustion engine;
• a second relatively large turbocharger including a second exhaust turbine situated in said first exhaust passage downstream of said first turbine;
• an exhaust bypass flow passage communicating with the first exhaust flow passage upstream and downstream of the first turbine;
• and
• an exhaust flow control valve operable to selectively permit or block exhaust gas flow through said exhaust bypass flow passage, wherein the exhaust flow control valve is located at a junction of the bypass flow passage and the first exhaust flow passage downstream of the first turbine to selectively permit or block flow to the second turbine from the first exhaust gas passage and the bypass passage;
• the method comprising:
• at least substantially stopping fuel supply to the internal combustion engine;
• and
• operating said exhaust gas control valve to at least partially restrict flow to the second turbine to thereby generate a braking back pressure at the internal combustion engine.