by wojciech » Sat Aug 25, 2018 9:54 am
Early models Mk3/4 with Bosch had solenoid (waxen medium inside) on a pump side. Solenoid has electric heater inside.
During long halt, cold solenoid pull short cord and lever on pomp, speed forward injection and put up idle little bit.
After start electric heater heats solenoid, it also catch temperature from engine - and cord is progressively loosened.
Solenoid was connected to ignition switch (to start-stop solenoid in injection pomp) through temperature sensor switch in engine block. Sensors switch is on only when engine got adequate temperature. Then electric heater in solenoid started to heat solenoid after 10-15 minutes after cold start. Practically it is too much of a good thing, system works very good (still long time after start) also without temperature sensor switch (solenoid connected directly to ignition switch).
Some models had installed on solenoid cord lever special adroit double sleeve - after sleeve turning cord is slack and system doesn't work. It is destined for summer time, for warm weather. It is a very good patent, because solenoid is not too much enduring, but expensive.