ICE Wouldn't shut off - 20-30 MPH

Earlier tonight I had a similar experience. No matter what, the ICE in my Prius wouldn't shut off. Stopped at a light, parked in a parking lot, etc; turns out that having the vent selector switch set to "defog" kept the ICE running!

Hope this helps.

 

That happens to me sometimes. In fact, I've experienced it several times in the last week or so. In a way, it's a bit alarming at first. (Well, it's alarming to a Prius driver. I imagine non-Prius folks would think us an odd bunch for expecting, even wanting, the engine to quit while in route!) Suffice it to say, your Prius isn't broken.

I can't speak with authority as to why it happens, but my guess is that the emissions system is a bit on the cool side and the HSD is trying to warm it up. Or perhaps the electrical load is too high for the battery's actual condition -- most, but not all, of my incidents have occurred early in my drive (2-15 minutes into it) while the A/C is working hard and I've been idle/crawling/low speed for a minute or two.

I just have to trust that the HSD is doing what it believes is best. It's not as if I can override it anyhow...

Is your mileage taking any more than a nominal hit because of this? I don't think it's happened often enough to make a measurable difference in my mileage. Keep in mind that you aren't driving a Power Wheels vehicle; the throttle is variable, so "engine on" does not necessarily mean you're getting poor fuel economy. And again, even if your instant mileage looks rotten during that time, the event is probably not significant enough to impact your overall numbers. (Smile: No matter what, you're still beating the snot out of everything around you in terms of MPG!)

- Justifyd

 

Your A/C can keep the engine running, believe it or not. Also, battery temperature can keep it from shutting down...

I also would love to have a function that displays why exactly it's running!

 

<div class='quotetop'>QUOTE(bigmahma @ Jun 5 2007, 09:07 AM) [snapback]455314[/snapback]</div>

My bet is you were in S3a...
http://techno-fandom.org/~hobbit/cars/five-stages.txt

Ken@Japan

 

I've heard on the plug-in hybrids they add a system called the can view. It lets you see the exact info on battery, temperature and all factors making the system run in gas-electric-glide. It's about 700 bucks so I don't want to know that bad.

I live in warm to hot arizona, I've have never had the ICE not shut down. Warm temps really helps.

It's still a great system ans gets better with each new generation. The 2008 with lithium batteries can get 90 mpg. If you drive like you care, I'm sure I'll get 100+ most of the time. It's that or the plug-in option for me. I want at least 100 mpg.

 

<div class='quotetop'>QUOTE(bigmahma @ Jun 5 2007, 08:06 AM) [snapback]455579[/snapback]</div>

I've had my car for almost a year and half, and I still haven't completely figured out the S3a/S3b/S4 deal. (But then I'm a slow learner sometimes. ) What supposedly triggers the transition from S3 to S4 is coming to a complete stop while in S3 and remaining there long enough for the ICE to shut off. There are times, sometimes 20-30 minutes into my drive and with a nicely warmed ICE, where I thought for sure I had done that, only to have the ICE light unexpectedly in situations similar to yours. (It's clear it's dependent on things other than ICE temperature.) It could be that between the characteristics of my commute, my (usually decent) timing of red lights, and coming to a stop only in ICE-off mode (S3b glides or EV mode) that I'm never actually letting it make that idle transition. It's something that I've been paying a little closer attention to recently so I can hopefully, finally get it nailed. I just got Can-view, so maybe that will help.

Meanwhile, take heart that you're not alone in either experiencing it or [edit] <strike>completely</strike> incompletely explaining it.

 

I've been wanting to post the same question but haven't gotten around to it.

I get in this as well, and find myself activating ev to glide, which is annoying not being able to go past 34 mph. If I think I can get a 4 second delay ice shutoff after coming to a stop I won't ev glide.

I've also had luck with doing a higher rpm pulse (2400 or so rpm) to get back into s4 which works in cases which I can't identify.

 

<div class='quotetop'>QUOTE(JimboK @ Jun 5 2007, 08:38 AM) [snapback]455591[/snapback]</div>

Wayne Mitchell(FireEngineer) showed me a little trick to get around the problem you're describing(S3b). If you come to a complete stop when the engine isn't running, with your foot firmly on the brake, push the gas pedal slightly until the engine starts then let off the gas and let the engine die. This will get you into S4 and the ICE will then only come on if the cat cools off too much or the A/C is on etc. This has worked like a charm for me since he showed this to me this past Saturday after he installed my block heater.

 

<div class='quotetop'>QUOTE(diamondlarry @ Jun 5 2007, 03:55 PM) [snapback]455943[/snapback]</div>

Thanks Larry, I had seen that described by Wayne and possibly others. The goal today on my cross town trip was to try it -- and pay attention this time. For the first two attempts the &%$#!* red light wouldn't stay red long enough for the ICE to die. This was on a busy thoroughfare so I didn't hang around after the light turned green. But I was ticked because of the 0.0251347 MPG or so it cost. Anyway, I made it happen on the third attempt. And it displayed S4 behavior from that point forward.

I think part of my problem in pinning it down is that my normal short commute has limited opportunities for the "S4 idle dance" (as I think Wayne calls it). It mostly hasn't been a problem because of my workarounds: accelerating into S3b range to allow ICE-off glides, and more recently using the new EV button at lower speeds. But it's been a source of frustration on longer trips when, again, I thought I had done the dance when apparently I hadn't.

 

<div class='quotetop'>QUOTE(diamondlarry @ Jun 5 2007, 12:55 PM) [snapback]455943[/snapback]</div>

There becomes a problem when one is timing all the traffic lights and never getting a chance to truly stop to do that trick! Usually I solve the problem by exceeding 56km/h and then the engine will get killed. But yes its an annoying feature espically for those who have tons of SHORT TRIPS and can use the engine killing ASAP before already arriving to their destination!

Must get speaker wire and button....

 

<div class='quotetop'>QUOTE(philmcneal @ Jun 23 2007, 07:39 AM) [snapback]466608[/snapback]</div>

Yes. The EV switch works here.
One of Japanese hypermilers technique is never move to S4.
He keeps Prius in S3, switch-off when he needs the ICE power and switch-on when he wants engine-off coasting.

Ken@Japan

 

<div class='quotetop'>QUOTE(jstack @ Jun 5 2007, 05:20 AM) [snapback]455585[/snapback]</div>

http://hybridinterfaces.ca/

It's not $700 and it's not a prerequisite that you turn your Prius into a plug in either. I've been tempted to buy one but it's too bad it won't work on the MFD of my 06 and that I'd have to shell out more $ for a separate LCD.

 

<div class='quotetop'>QUOTE(ken1784 @ Jun 22 2007, 08:48 PM) [snapback]466664[/snapback]</div>

Ken, why does he do that? Unless he doesn't have an opportunity to stop for the S4 idle shutdown, it would seem that his technique serves no fuel economy benefit, and certainly requires repeated pushing of the button that S4 wouldn't require.

 

<div class='quotetop'>QUOTE(diamondlarry @ Jun 5 2007, 02:55 PM) [snapback]455943[/snapback]</div>

I do the same thing if I coast to a stop in EV while in s3, turn off EV, ice comes back on then you get 4 second shutoff and voila.

Is there a speed threshold that will put you in s4 without 4 second shutoff?

Is the fuel burn the same in s3 as s4? Can-viewers? Anybody? i.e. is it still burning extra to heatup something ?

 

<div class='quotetop'>QUOTE(douglas001001 @ Jul 10 2007, 04:13 PM) [snapback]476338[/snapback]</div>

I think I heard Wayne(FireEngineer) say that a speed of 35 mph or more for 10 minutes will put you in S4.

 

<div class='quotetop'>QUOTE(bigmahma @ Jun 4 2007, 08:07 PM) [snapback]455314[/snapback]</div>

This happens to me sometimes. What I do is accelerate above 35 MPH. It seems to work normally after that.

 

<div class='quotetop'>QUOTE(bestmapman @ Jul 10 2007, 04:36 PM) [snapback]476358[/snapback]</div>

Could the ECU think that the catalytic converter was too cool and the engine needs to start to warm it up?