Dear Dave:<br>When we are in "stealth" mode, stop the car, and shift into "P", sometimes the ICE starts up, and sometimes it doesn't. It's very annoying when it starts up, because when we shift into "P" we intend to shut the car off. To have the ICE start up just prior to shutting off the car is disconcerting. Are we supposed to let the ICE "idle" until it shuts off before shutting off the car? And why does it do it SOME of the time, and not others? <br><br>We've elucidated many mysteries of the Prius, but this one has escaped explanation. Please help.<br><br>Thanks,<br>Sam, et al.

Sam, et al.<br><br>My contacts in Japan offer the following two possible scenarios:<br><br>* In D and P two different values are used for engine on strategy. In D we use 10 kW load (sum of road load, acceleration and battery need). In P a much lower value is used (to recover SOC). If the battery need component is the major element of the total load requirement, then the syustem may start to charge the battery when you shift into P.<br><br>* Second scenario, we use a learning value for idle speed control. During D, the first priority is given to stopping the engine to maximize efficiency. If on the shift to P, the system isn't happy with its learned ISC value, it may run the engine briefly to update the value.<br><br>Hope this answers your question.<br><br>Dave

This is extremely helpful, Dave, however the question remains: Is it a problem under either scenario to turn the car off if/while the engine is running after shifting into park? Should the engine be allowed to run, howeever briefly or long, until it shuts itself off? Thanks for the further clarification.<br>Alan

Sorry I left on open issue. Shut down at your convenience. The system is doing housekeeping and if shut down will just do it at the next chance.<br><br>Dave

I've noticed that Baby doesn't run-on as much with AC on. (usually the ICE has run within a minute or two before engaging P, due to compressor cycling)<br><br>Also, my ICE shut down immediately (after P-induced start-up) upon opening the driver's door.<br>(this I'll investigate further)<br><br>SOC and idle speed coefficent (plus mixture/misfire values) should be independent of the gear selected.<br><br>It'll be interesting to see how the '02 behaves.<br><br>Jeff (betting my money on the THS second-guessing driver's intent--with the battery fully charged and system warmed up, that is)