Last post on Aug 25, 2008 at 12:05 AM
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Engine, Fuel System, Transmission, Hybrid Cars, Coupe, Convertible, Hatchback, Truck, Sedan, SUV
#204 of 206 A question to Toyolla2..
Aug 21, 2008 (5:58 am)
...that I have not been able to find an answer anywhere on the net.
In the HSD system - at startup - at a standstill - there is a 10 sec delay designed into the running of the drive system. This I believe is called phase 0 in some discussions. The vehicle is READY if the driver chooses to drive immediately but if the vehicle remains stationary then nothing happens until the ICE kicks in - giving a boost to the traction battery.
My admittedly non-technical hypothesis is that MG1 draws some juice from the traction battery to get the ICE pumping and spinning without actually injecting any fuel into the cylinders. This to make the ICE ready to jump into action in an efficient state. If the vehicle doesn't actual go into drive mode then the ICE starts to pump fuel and generate power which goes to 'pay back' the juice borrowed initially.
After the ICE has paid back its debt it shuts down until needed.
How much of this is accurate? Thanks
#205 of 206 Re: A question to Toyolla2.. [kdhspyder]
Aug 21, 2008 (6:14 am)
I believe the HSD system waits about 7 seconds after ready before starting the ICE, if necessary. MG1 will spin the ICE only if it intends to start it and spins it up to about 1000 RPM without fuel or sparks until oil pressure is established. Once oil pressure is established fuel and sparks are added and you have a running ICE.
#206 of 206 Re: A question to Toyolla2.. [kdhspyder]
Aug 25, 2008 (12:05 am)
I am not saying this is the answer.... but my understanding is that whenever the engine starts up it must continue until it has brought the Oxygen sensor up to temperature.I seriously doubt that one start cycle alone is a significant battery draw to require a recharge.
The 10 second delay on the Prius system engine startup may be the coolant temperature bypass valve allowing hot fluid stored in the thermos reservoir to be circulated through the engine. When that has been accomplished it enables starting of the engine to proceed.
Why is it programmed to do this ? I can only guess that the assumption is that if the car is not going to be moved in electric mode after a reasonable time delay, all bets can be covered if the engine is pre-emptively 'prepped'.