Automatic EV-Traction mode during warmup?

echase · 06-06-2007, 09:57 PM

I've noticed that while the car is warming up, as long as my acceleration is less than about 3/4 of the pedal the engine stays at a constant RPM. It seems to display exactly the same behavior as if I were in EV mode, but with the ICE on. This only lasts a few minutes at most, then the ICE seems to be actually used for traction.

Can anyone debunk or support my theory that the prius uses EV traction only during ICE warmup?

**efusco** · 06-06-2007, 10:04 PM

Yea, I find the car very much "wants" to run at 1275rpm (per CAN-View, your device may vary a little) and will let the amperage drain go up pretty high (like EV mode) before it'll kick up the ICE rpm.

I think this is to minimize emissions during warm up. I've taken to trying to keep the amperage draw to <-12 amps during this period to minimize battery drain...as soon as I see the ICE rpm start to flutuate I begin my usual Pulse & glide with a target rpm of 1850...I've been seeing some pretty dramatic improvement in FE with this technique.

ken1784 · 06-06-2007, 10:20 PM

I think your observation is correct.
Speaking of Japanese Prius...
During the first 57 seconds (S1a), the ignition timing is very late, after about 9 degrees from the top end, which means the exhaust gas becomes very hot to warm up the catalyst quickly and no good drive torque is produced. Then, it goes in EV mode only.
You can find that the engine noise changes after 57 seconds from starting if you do stand still warming up in Park position.

Ken@Japan

06-06-2007, 10:04 PM	#2
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 14,253 My Car: 2004 Prius Package: #9 Nominated 1 Time in 1 Post TOTM Awards: 0 Friends: 24	Yea, I find the car very much "wants" to run at 1275rpm (per CAN-View, your device may vary a little) and will let the amperage drain go up pretty high (like EV mode) before it'll kick up the ICE rpm. I think this is to minimize emissions during warm up. I've taken to trying to keep the amperage draw to <-12 amps during this period to minimize battery drain...as soon as I see the ICE rpm start to flutuate I begin my usual Pulse & glide with a target rpm of 1850...I've been seeing some pretty dramatic improvement in FE with this technique. __________________ Evan E. Fusco, MD Seaside 04BC9/OEM EVb/NAV & auto-BT/XM Radio, CAN-View, Shark Fin, BT Stiff. Plate, Skid Plate & Strut Support

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06-06-2007, 09:57 PM	#1
echase Senior Member Join Date: Sep 2006 Posts: 204 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 2	I've noticed that while the car is warming up, as long as my acceleration is less than about 3/4 of the pedal the engine stays at a constant RPM. It seems to display exactly the same behavior as if I were in EV mode, but with the ICE on. This only lasts a few minutes at most, then the ICE seems to be actually used for traction. Can anyone debunk or support my theory that the prius uses EV traction only during ICE warmup?

06-06-2007, 10:20 PM	#3
ken1784 SuperMID designer Join Date: Dec 2003 Location: Yokohama, JAPAN Posts: 1,391 My Car: 2004 Prius Package: G Touring Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 3	I think your observation is correct. Speaking of Japanese Prius... During the first 57 seconds (S1a), the ignition timing is very late, after about 9 degrees from the top end, which means the exhaust gas becomes very hot to warm up the catalyst quickly and no good drive torque is produced. Then, it goes in EV mode only. You can find that the engine noise changes after 57 seconds from starting if you do stand still warming up in Park position. Ken@Japan