Finally -- I've felt surging in the ICE

a priori · 12-08-2007, 09:34 PM

This happened with a warm engine, even though it was a cold day. I had been driving for more than 30 minutes in a mix of highway and main roads when I felt a slow, steady pulsing in the ICE. I had been approaching a red light when I allowed the car to slow down. The light turned green, and I was just starting to slowly accelerate. The battery was showing 7 green bars, and the ICE was not engaged (at least according to the MFD) as I gradually accelerated from the low-30s up to 40 mph. As I hit 40 mph, just before I would expect the ICE to kick in, the surging started. I was quite surprised. The surging stopped as soon as I increased the rate of acceleration.

I've never felt the surging before (or since), and I'm wondering if anyone knows (or can guess at) the cause for this surging actvity.

brick · 12-08-2007, 10:41 PM

Guess? I can play that game for hours

I'm good at Speculate, too.

My guess is going to be that you felt the engine starting up and taking the load. 41mph is the point at which the engine must be spinning, so if it isn't on already it will fire up. If you don't have a tach, the only way of knowing is that you will feel a "thump" or perhaps...maybe...a "surge" while the car makes the transition. The engine and wheels, and electric motor are always connected to one another via the PSD. I think that's why a particularly attentive driver feels engine start/stop events; it's not isolated like it would be if it were a regular transmission in neutral.

Part of the reason I like having a tachometer is that it takes much of the mystery out of the car's behavior. If I feel the car do something and see the needle jump at the same time, I don't give it a second thought.

a priori · 12-08-2007, 11:03 PM

I don't think I felt it just picking up the load. I really was just headed to 40mph, and I was on a level road. My acceleration was quite slow.

I felt the gentle surging for quite some time. It felt to me as though it would continue unabated, and it only went away when I pressed to accelarate to a higher speed.

I suppose I'm just posting an observation, yet I'd be curious to hear opinions as to why it happened. I had not experienced any surging before, and the circumstances didn't seem to match up with what I'd read in earlier posts. In most other posts, I'd seen a relation to cold engine, and that clearly didn't exist here. Also, I was at a very high SOC on the battery.

fruzzetti · 12-08-2007, 11:13 PM

I think what he was trying to describe is a repetitive restart-shutdown, as though the load demand keeps oscillating just above the start-trigger and below the shutdown-trigger; I'd expect the car to be intelligent enough to require a cycle time or some other delay between restart events, but maybe his car is doing like my old microwave did every once in a while?

~ dan ~

a priori · 12-08-2007, 11:22 PM

Certainly, this could be the case, though I really do not know. I'm just commenting here on an interesting experience.

I was trying to stay at or just below 40mph, though, and the MFD did not show that the ICE was engaged. Now I know the MFD doesn't show everything, but the surging was happening while I held right at 40mph on a level surface where no ICE involvement was showing on the MFD. I thought I felt the ICE, because I felt the surging and believed it was the ICE engaging.

bwilson4web · 12-09-2007, 07:34 AM

Quote:

Originally Posted by a priori

Certainly, this could be the case, though I really do not know. I'm just commenting here on an interesting experience.

I was trying to stay at or just below 40mph, though, and the MFD did not show that the ICE was engaged. Now I know the MFD doesn't show everything, but the surging was happening while I held right at 40mph on a level surface where no ICE involvement was showing on the MFD. I thought I felt the ICE, because I felt the surging and believed it was the ICE engaging.

One of my 'lessons learned' is to keep a guard-band around 42 mph. I'll slow down to 38 mph or speed up to 46 mph but I try to minimize transitions through 42 mph. My mileage data using cruise control to govern the speed showed that 42 mph in city driving gives a the worst mileage. Yet in controlled tests on level roads without other traffic, 42 mph fits on the drag curve.

Bob Wilson

Prius 07 · 12-09-2007, 08:58 AM

deleted posted in wrong thread

bnaccs · 12-11-2007, 10:09 PM

What is ICE?

Rae Vynn · 12-11-2007, 10:22 PM

Quote:

Originally Posted by bnaccs

What is ICE?

Internal Combustion Engine

The Hybrid Synergy Drive switches back and forth between using the ICE and electric, and just the electric, as needed.
The trick to really awesome MPG is to use the ICE as little as possible, and thus very little gas. The ICE automatically engages at 42 MPH, in order to be available (without shearing off a driveshaft or something like that) when needed by an increased load on the engine.

[Disclaimer: I am not a mechanic, nor do I play one on TV. There are mechanics here that can explain the HSD much better than I]

dogfriend · 12-14-2007, 09:46 PM

Quote:

Originally Posted by bnaccs

What is ICE?

In the hybrid world, it is an acronym for Internal Combustion Engine.

In everyone elses world, it is frozen water.

12-08-2007, 09:34 PM	#1
a priori Senior Member Join Date: Aug 2007 Location: Chicagoland (West) Posts: 673 My Car: 2007 Prius Package: #8 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 1	Finally -- I've felt surging in the ICE This happened with a warm engine, even though it was a cold day. I had been driving for more than 30 minutes in a mix of highway and main roads when I felt a slow, steady pulsing in the ICE. I had been approaching a red light when I allowed the car to slow down. The light turned green, and I was just starting to slowly accelerate. The battery was showing 7 green bars, and the ICE was not engaged (at least according to the MFD) as I gradually accelerated from the low-30s up to 40 mph. As I hit 40 mph, just before I would expect the ICE to kick in, the surging started. I was quite surprised. The surging stopped as soon as I increased the rate of acceleration. I've never felt the surging before (or since), and I'm wondering if anyone knows (or can guess at) the cause for this surging actvity. __________________ Some knowledge may be readily grasped as it is apparent to even the most casual viewer, but most of us learn this only by experience after having ignored what was right before our eyes.

12-08-2007, 11:03 PM	#3
a priori Senior Member Join Date: Aug 2007 Location: Chicagoland (West) Posts: 673 My Car: 2007 Prius Package: #8 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 1	Just an Observation, Really I don't think I felt it just picking up the load. I really was just headed to 40mph, and I was on a level road. My acceleration was quite slow. I felt the gentle surging for quite some time. It felt to me as though it would continue unabated, and it only went away when I pressed to accelarate to a higher speed. I suppose I'm just posting an observation, yet I'd be curious to hear opinions as to why it happened. I had not experienced any surging before, and the circumstances didn't seem to match up with what I'd read in earlier posts. In most other posts, I'd seen a relation to cold engine, and that clearly didn't exist here. Also, I was at a very high SOC on the battery.

12-09-2007, 08:58 AM	#7
Prius 07 Senior Member Join Date: Jun 2007 Location: Toronto, Canada Posts: 447 My Car: 2007 Prius Package: #5 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	deleted posted in wrong thread Last edited by Prius 07; 12-09-2007 at 09:01 AM. Reason: posted in wrong thread

12-08-2007, 10:41 PM	#2
brick Senior Member Join Date: Dec 2006 Location: Columbia, SC Posts: 598 My Car: 2007 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Guess? I can play that game for hours I'm good at Speculate, too. My guess is going to be that you felt the engine starting up and taking the load. 41mph is the point at which the engine must be spinning, so if it isn't on already it will fire up. If you don't have a tach, the only way of knowing is that you will feel a "thump" or perhaps...maybe...a "surge" while the car makes the transition. The engine and wheels, and electric motor are always connected to one another via the PSD. I think that's why a particularly attentive driver feels engine start/stop events; it's not isolated like it would be if it were a regular transmission in neutral. Part of the reason I like having a tachometer is that it takes much of the mystery out of the car's behavior. If I feel the car do something and see the needle jump at the same time, I don't give it a second thought.

12-08-2007, 11:13 PM	#4
fruzzetti Customization-Obsessed Join Date: Dec 2007 Location: Hayward, CA USA Posts: 295 My Car: 2006 Prius Package: #7 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I think what he was trying to describe is a repetitive restart-shutdown, as though the load demand keeps oscillating just above the start-trigger and below the shutdown-trigger; I'd expect the car to be intelligent enough to require a cycle time or some other delay between restart events, but maybe his car is doing like my old microwave did every once in a while? ~ dan ~

12-08-2007, 11:22 PM	#5
a priori Senior Member Join Date: Aug 2007 Location: Chicagoland (West) Posts: 673 My Car: 2007 Prius Package: #8 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 1	Certainly, this could be the case, though I really do not know. I'm just commenting here on an interesting experience. I was trying to stay at or just below 40mph, though, and the MFD did not show that the ICE was engaged. Now I know the MFD doesn't show everything, but the surging was happening while I held right at 40mph on a level surface where no ICE involvement was showing on the MFD. I thought I felt the ICE, because I felt the surging and believed it was the ICE engaging.

12-11-2007, 10:09 PM	#8
bnaccs bnaccs Join Date: Dec 2007 Location: Colorado Posts: 38 My Car: Other Non-Hybrid Package: N/A Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	What is ICE?