ICE keeps turning on during commute

philaprius · 11-08-2007, 03:03 PM

I have been driving my 2007 Prius for several months now. It's performed as expected for the most part (my commute is 3-4 miles in the city) and I seem to get 36-38 mpg on average on those trips, 50 mpg on the highway on my weekend trips, and closer to 55-60 mpg when I get to drive in the burbs.

My question is this. Sometimes the ICE turns on again in the middle of my drive. It does an ignition cycle on start up as usual and then turns off after 5 minutes (after which I can pulse and glide). However, five to ten minutes later after the engine turns off at a stoplight, it will suddenly turn on again and stay on until I come to the next complete stop. Then it functions normally again, kicking in only when I accelerate. If I stop again, the engine sometimes comes on again until the next stop. It's weird. I don't use the AC or heat when this is happening and my battery is 3-4 bars, so I can't think of another reason the ICE would be turning on.

This doesn't happen every day.. maybe just once a week. Any ideas/insight as to why this would happen? Any thoughts are appreciated...

**efusco** · 11-08-2007, 04:03 PM

Probably the cold weather...such a short commute you're probably not getting the ICE temp all the way up.

Consider grill blocking and an engine block heater...it'll help that short commute mileage a lot, give you a warm cabin sooner, and stop that unnecessary wasteful ICE starting.

douglas001001 · 11-08-2007, 04:16 PM

It sounds like you might be getting the passing 80 deg c water pump cycle, where the ice won't shut off if it turns on in the middle of it. Usually lasts like a minute.. some force shutoff with ev switch when this occurs.

Since you are saying you can p&g after 5 minutes, you've at least crossed the 70 deg c barrier and this happens a few minutes after that, so that is my guess.

philaprius · 11-08-2007, 04:51 PM

<div class='quotetop'>QUOTE(efusco @ Nov 8 2007, 04:03 PM) [snapback]536874[/snapback]</div>

Quote:

Probably the cold weather...such a short commute you're probably not getting the ICE temp all the way up.

Consider grill blocking and an engine block heater...it'll help that short commute mileage a lot, give you a warm cabin sooner, and stop that unnecessary wasteful ICE starting.
[/b]

Thanks for the input. Sadly, I don't have a garage so an engine block heater is not possible.... Also, it's happened during the summer as well so I'm not sure if it's due to the ICE not getting warm enough. It happens after the initial ignition cycle for the ICE (at which time I assume it has reached its internal temp). The ICE then turns off so I can pulse and glide. Then for some reason it turns on again at a stop light and stays on until I come to the next complete stop, at which time it starts behaving normally, allowing me to P+G again...

<div class='quotetop'>QUOTE(douglas001001 @ Nov 8 2007, 04:16 PM) [snapback]536881[/snapback]</div>

Quote:

It sounds like you might be getting the passing 80 deg c water pump cycle, where the ice won't shut off if it turns on in the middle of it. Usually lasts like a minute.. some force shutoff with ev switch when this occurs.

Since you are saying you can p&g after 5 minutes, you've at least crossed the 70 deg c barrier and this happens a few minutes after that, so that is my guess.
[/b]

Thank you too for your input. This explanation sounds interesting but I don't quite understand.. What is the 80 deg C water pump cycle? Is this normal behavior for my Prius? It really drops my mileage, and will stay on for minutes until I come to a stop, which seems to put things back in order with the ICE staying off. Although as I mentioned, it might happen again a few minutes later at another stop sign.

I can't go into a EV only mode while the ICE is on it seems. The only way I've stoped it is to halt the car completely which isn't always feasible...

Thanks again!

philaprius · 11-08-2007, 04:56 PM

<div class='quotetop'>QUOTE(douglas001001 @ Nov 8 2007, 04:16 PM) [snapback]536881[/snapback]</div>

Quote:

It sounds like you might be getting the passing 80 deg c water pump cycle, where the ice won't shut off if it turns on in the middle of it. Usually lasts like a minute.. some force shutoff with ev switch when this occurs.

Since you are saying you can p&g after 5 minutes, you've at least crossed the 70 deg c barrier and this happens a few minutes after that, so that is my guess.
[/b]

Thank you too for your input. This explanation sounds interesting but I don't quite understand.. What is the 80 deg C water pump cycle? Is this normal behavior for my Prius? It really drops my mileage, and will stay on for minutes until I come to a stop, which seems to put things back in order with the ICE staying off. Although as I mentioned, it might happen again a few minutes later at another stop sign.

I can't go into a EV only mode while the ICE is on it seems. The only way I've stoped it is to halt the car completely which isn't always feasible...

Thanks again!

douglas001001 · 11-08-2007, 05:12 PM

<div class='quotetop'>QUOTE(philaprius @ Nov 8 2007, 05:51 PM) [snapback]536896[/snapback]</div>

Quote:

What is the 80 deg C water pump cycle? Is this normal behavior for my Prius?
[/b]

When the coolant temp passes 80 degC, the water pumps come on, I think it is to mix the coolant that is stored in the thermos. Someone else would have to give more on the specifics, but the ice probably stays on so the battery doesn't get used for this process.

Last winter I didn't have a scan gauge to monitor this, I don't remember if it happens every time you cross over the threshold, but if you are P&g'ing and your coolant temp is around 80 and the weather is colder you can bounce above and below that every few minutes. Its down in the 40s here now, I'll report back as I'll probably encounter this more frequently in the next few days.

As efusco suggests, try grill blocking as this will help to keep the heat in once you're up to temp (use search function on here for many threads).

**efusco** · 11-08-2007, 06:27 PM

You're probably not in Stage 4 and what you're experiencing at the first stop is that you're slowing from a speed higher than 35mph and the car will go into stealth from that speed.
At the second stop I'd venture that you are slowing to a stop from a speed below 35mph...since you're not in S4 the ICE will continue to run for about 5-6 seconds at that stop. Once it shuts off while stopped you're in stage 4 and it should shut off at any speed when you slow down.

morpheusx · 11-09-2007, 08:02 AM

If its cold outside as much as you may want the cabin heat try turning the heater fan to the lowest speed or off and try a lower temp. Test it out at a stop light or drive thru and most likely your ICE will instantly turn off. The higher the settings the more heat it is drawing from the coolant, therefore forcing the ICE to warm the coolant back up.

JimN · 11-10-2007, 11:58 PM

Philaprius, the ICE is running to either keep itself or you warm. If you turn off the climate control or reduce fan speed at the traffic light and the engine turns off then it is a question of your personal comfort. (Don't get the cabin too cold as the battery needs some heat which is obtained through the vent by the back seat. Low 70's should be OK. It really depends on how much sun the car gets.) Placing pipe insulation in the grill retains heat so the ICE doesn't have to run as much to keep itself warm.

There is a tow truck driver in the neighborhood that runs an extension cord from the house to the truck parked on the street.

wyounger · 11-29-2007, 07:05 PM

With such short commutes the car may need to run the ICE extra here and there so it can squeeze in all of the self-tests of the emissions system required on 1996-up vehicles. There is some background business getting done and with these very short drive cycles it might just need extra ICE time for the test routines to finish.

Even if it's the case I'm sure it's still frustrating. Just keep in mind that Toyota doesn't have 100% flexibility to be green; they have to conform to the same regulations as everyone else too.

11-08-2007, 06:27 PM	#7
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 14,709 My Car: 2004 Prius Package: #9 Nominated 1 Time in 1 Post TOTM Awards: 0 Friends: 26	You're probably not in Stage 4 and what you're experiencing at the first stop is that you're slowing from a speed higher than 35mph and the car will go into stealth from that speed. At the second stop I'd venture that you are slowing to a stop from a speed below 35mph...since you're not in S4 the ICE will continue to run for about 5-6 seconds at that stop. Once it shuts off while stopped you're in stage 4 and it should shut off at any speed when you slow down. __________________ Evan E. Fusco, MD Seaside 04BC9/OEM EVb/NAV & auto-BT/XM Radio, CAN-View, Shark Fin, BT Stiff. Plate, Skid Plate & Strut Support

11-10-2007, 11:58 PM	#9
JimN Certified Prius Advisor Join Date: Nov 2006 Location: South Jersey Posts: 2,237 My Car: 2006 Prius Package: #3 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Philaprius, the ICE is running to either keep itself or you warm. If you turn off the climate control or reduce fan speed at the traffic light and the engine turns off then it is a question of your personal comfort. (Don't get the cabin too cold as the battery needs some heat which is obtained through the vent by the back seat. Low 70's should be OK. It really depends on how much sun the car gets.) Placing pipe insulation in the grill retains heat so the ICE doesn't have to run as much to keep itself warm. There is a tow truck driver in the neighborhood that runs an extension cord from the house to the truck parked on the street. __________________ 2006 Magnetic Gray "Spirit Queen" TP 45, Blocked grill, Toyota rear bumper applique, VentureShield panels: Hood, bumper & headlights 2000 Intrigue "Lil Deuce Coupe" 1999 EV-1 Range 220 miles 2000 Precept diesel-electric hybrid 80mpg The reason I own a Prius. Thank you, GM.

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11-08-2007, 03:03 PM	#1
philaprius Join Date: Sep 2007 Posts: 5 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I have been driving my 2007 Prius for several months now. It's performed as expected for the most part (my commute is 3-4 miles in the city) and I seem to get 36-38 mpg on average on those trips, 50 mpg on the highway on my weekend trips, and closer to 55-60 mpg when I get to drive in the burbs. My question is this. Sometimes the ICE turns on again in the middle of my drive. It does an ignition cycle on start up as usual and then turns off after 5 minutes (after which I can pulse and glide). However, five to ten minutes later after the engine turns off at a stoplight, it will suddenly turn on again and stay on until I come to the next complete stop. Then it functions normally again, kicking in only when I accelerate. If I stop again, the engine sometimes comes on again until the next stop. It's weird. I don't use the AC or heat when this is happening and my battery is 3-4 bars, so I can't think of another reason the ICE would be turning on. This doesn't happen every day.. maybe just once a week. Any ideas/insight as to why this would happen? Any thoughts are appreciated...

11-08-2007, 04:03 PM	#2
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 14,709 My Car: 2004 Prius Package: #9 Nominated 1 Time in 1 Post TOTM Awards: 0 Friends: 26	Probably the cold weather...such a short commute you're probably not getting the ICE temp all the way up. Consider grill blocking and an engine block heater...it'll help that short commute mileage a lot, give you a warm cabin sooner, and stop that unnecessary wasteful ICE starting.

11-08-2007, 04:16 PM	#3
douglas001001 smug doug Join Date: Mar 2007 Location: Chicago Posts: 207 My Car: 2007 Prius Package: #6 Touring Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 1	It sounds like you might be getting the passing 80 deg c water pump cycle, where the ice won't shut off if it turns on in the middle of it. Usually lasts like a minute.. some force shutoff with ev switch when this occurs. Since you are saying you can p&g after 5 minutes, you've at least crossed the 70 deg c barrier and this happens a few minutes after that, so that is my guess.

11-09-2007, 08:02 AM	#8
morpheusx Professor Chaos Join Date: Mar 2007 Location: Akron, OH Posts: 1,263 My Car: 2007 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 3	If its cold outside as much as you may want the cabin heat try turning the heater fan to the lowest speed or off and try a lower temp. Test it out at a stop light or drive thru and most likely your ICE will instantly turn off. The higher the settings the more heat it is drawing from the coolant, therefore forcing the ICE to warm the coolant back up.

11-29-2007, 07:05 PM	#10
wyounger Member Join Date: Feb 2007 Location: Atlanta, GA USA Posts: 56 My Car: 2007 Prius Package: #5 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	With such short commutes the car may need to run the ICE extra here and there so it can squeeze in all of the self-tests of the emissions system required on 1996-up vehicles. There is some background business getting done and with these very short drive cycles it might just need extra ICE time for the test routines to finish. Even if it's the case I'm sure it's still frustrating. Just keep in mind that Toyota doesn't have 100% flexibility to be green; they have to conform to the same regulations as everyone else too.