Cold start vs hot start on a testarossa

Overnight

 

it depends where you store the car. in a cooling warehouse with -13 ° F it needs 2 hours I would say.

 

The answer to this is slightly different for a K-Jet TR versus a KE-Jet TR -- since your location in your Profile is in the US, I'll assume that you have a US version KE-Jet TR (please let me know if otherwise). Also, there are really three different starting modes for a US version TR (not just two):

Mode 1. Both TTS and coolant thermoswitch closed = temperature of entire engine and coolant < about 68 deg F = cold start injectors squirt during initial starter cranking, and injection system operates in open-loop mode until coolant reaches a temp > about 145 deg F. This usually gives a "crisp" initial firing as the fuel squirt from the cold start injectors is ignited.

Mode 2. TTS open (engine and coolant > about 68 deg F), but coolant thermoswitch closed (engine and coolant has gone below about 92 deg F) = cold start injectors do not squirt during initial starter cranking, and injection system operates in open loop mode until coolant reaches a temp > about 145 deg F. For me here in TX, even after overnight, my TR starts in this mode from about late April to late Oct as the ambient temp in my garage never goes below 68 deg F so the TTS never closes, but it does go below 92 deg F for an extended time so the coolant thermoswitch does close. Starting in this mode is much more "sluggish" (without the cold start injector squirts) than Mode 1 .

Mode 3. TTS open and coolant thermoswitch open = occurs after use and the coolant has never gone back below 92 deg F = the typical warm restart = cold start injectors do not squirt and the injection system goes into closed-loop mode in just a short time after starting.

(Agree with the others that it takes many, many hours after being fully warmed up to go back to Mode 1 or Mode 2 starting operation -- the engine and its fluids are a big turkey that take takes a long time for the inside to get to the same temperature as the outside.)