Rough Idle

What type of fuel are you using??? Ethanol or unleaded regular...I've found that my Toyota Camry is sensitive to the type of fuel...I had rough idle and was using a higher octane fuel...also experienced this with Ethanol...I now use only regular unleaded.

Mike

 

just as a thought, I wonder if by using the EV too much might pull the battery to a lower state of charge that the computer has to run the the ICE to get it up to charge, and it's just waiting for it get there. Also when my 2k3 is getting ready to cycle the ICE off it get's shaky. The 2K1 the wife had made more of a clean stop compared to my 2k3 and her 2k4 which both have a bit of a shaky period just before shut down. Keep us informed on this one.

 

2-4 misses should set a MIL/CEL code in the computer Might not put the MIL on but should set a code.

 

Boy, it's reassuring for us new Prius drivers to find threads like this!

My new (almost 2 months old, actually) Prius works great, but the only thing I've been at all concerned about is a "rough idle" situation.

Specifically, in the morning when the car has been started from a cold state, I:

• 
  I.e., I have my foot on the brake, and the car is in Drive (D). The car engine does not stop, even after about 10 seconds.
  This doesn't bother me -- in fact, if I read Daniel's excellent article on the 5 stages of Prius operation correctly, this is to be expected, because the car is still in stage S1, and hasn't warmed up yet.
  
  However, the car does seem to shudder a bit-- as if the engine is running rough, and it's causing the car to shudder.
  
  I seem to remember that, if I switched the heat (i.e., AC) off, then the engine would shut down; but I may be mixing that up with other occasions
  [hr:491c064f02]
  So, main question: is this behavior normal in an 04/05 Prius? Are other people seeing this in their cars? Besides htmlspinnr's comments, there were similar observations in the ICE runs rough as it shuts down thread -- but I'm not entirely sure that we're witnessing the same symptoms.
  
  At any rate, I'm not bothered by the occasional shudder -- I just wanted to make sure I wasn't seeing the first sign of something worse. If anyone asks, I just tell 'em my Prius is "throbbing with power". :mrgreen:

 

Weird...

Funny you should be talking about this. I have had my car less than a week and I noticed this exact situation today for the first time. I had stopped at a store for about 1/2 hour and was starting back home. The temp was about 45 degrees. Engine cold - not sure of SOC. First engine starts while in reverse, noticed a little rough. Since I'm in reverse it is definitely idle state.

Then switch to drive. Because I am in parking lot, forward motion is all electric, and my force is light on the gas pedal. I come to a stop at light. Car starts to shudder noticeably, then engine kicks off.

Next couple of engine cycles notice some roughness, but less and that was it.

I have had colder starts, basically just from home but haven't noticed this before except for the one time today.

I will take note of SOC and any indication of recharging if this happens again.

 

I have once got crappy gas from a Speed Way. I have to use premiun on the Evo. My car is soo susectible to knocking with crappy gas. Maybe you got a bad batch? Just a suggestion.

 

Jeff when I've seen this happen it is just as the car is ready to go to S4 but the BSOC is at say 59% and it want's 60% and 70C and 42 mph or 6 seconds full stop for S4. As the BSOC climbs to 60% you will get a ragged shut down of the ICE if your stopped. It probably does it as well at road speed but the roughness isn't noticable.

 

I've noticed what Jeff descibes in his post once or twice (it doesn't get super-cold here in Austin that often--in fact, it's 70 something out right now. Ahh... Jan in Austin). Anyhow, the times I've noticed it, it's been very cold out, the car is cold (sitting overnight in the garage), and I've had the heat on. After the first stop, when the car idled roughly and kind of shuddered at the first stoplight and the ICE didn't shut down, the car behaved more normally at subsequent stops. I also assumed it was normal behavior for the car when cold.

 

Yup -- the key point is that the engine doesn't shut down at the stop -- it just idles roughly, causing the car to shudder occasionally.

I've assumed that this is due to the heat (AC) being on, and thus the computer wants to keep the ICE running so that heat is generated for the driver and passengers.

However, since so many other people are seeing this (thank you all for responding!), I'm going to consider this normal behaviour, declare victory, and not worry about it.

 

I noticed the rough idel issue during the last cold spell here in Dallas. It's almost like the engine wants to shut down while I'm stopped, but changes it's mind. It was a rough idle at that first stop with a cold engine.

It's warmed back up here over the past week and the issue hasn't occured again.

 

I get the shudder each morning I drive off to work heat or no heat.
It always happens at the first stop sign about six blocks from the house.
After that it may happen once more if it is a bit chilly out otherwise it's smooth driving the rest of the way to work.

 

Well, for the people complaining about rough idling when the engine is warming up just after start up, that's not too surprising given the operating mode the Prius is in at that time. In order to heat up the cat faster while still keeping emissions down, (Toyota claims that) the Prius runs with retarded timing and a stoichiometric mixture.

That will cause any engine to run very rough.

However, I get this happening sometimes even with a warm engine... not sure what that's about. If it doesn't go away after the breakin period I'll probably take it in for a look at the dealer... not that I expect it to be easy to explain that I understand why it's doing it sometimes but am concerned about it doing it other times .

 

On New Year's Eve, my friend and I and his daughter were doing some last minute errands. had to stop at a light, car shuddered a bit before shutting down ICE. I said "Oh man, out of gas". My friend started laughing, and his daugher almost took me seriously.

It may be shuddering due to remaining fuel vapors in the intake when the intake valve timing is left open during the early part of the compression stroke, thus pushing some fueled air back into the intake. If only they could do direct in-cylinder fuel injection, then they could inject after the intake valve closes. As it is, the injection is just behind the valve.

 

<div class='quotetop'>QUOTE(DanMan32\";p=\"61460)</div>

:lolup: I am waiting for a situation like that with great anticipation...

 

Mine has never idled rough when cold or warm, even at -35 C. When cold, it can give the rare shudder-before-stop.

Note to self: move to warmer climate ASAP. BRRR

 

<div class='quotetop'>QUOTE(jayman\";p=\"61607)</div>

Perhaps your Prius has acclimated to the cold, while those of us who shudder at the thought of below 50 temps have cars that do the same .