Has the rough cold start issue being corrected?

No, there's been no fix reported.

Most people (but not all) report that it happens when the car sits for 8+ hours after they turned it on only briefly; e.g. to move it from the street to the garage. But even then, it doesn't seem to be guaranteed to happen. Most people only encounter it rarely - I've never experienced it - so you're perhaps not "lucky" but just "average".

 

I think I had 1 rough start in 36000+ miles. It was COLD with at least a foot of snow on the ground.

 

I had two "rough start" issues within the first 5000 miles on my car. Both times after moving car short distance, driveway to garage, and stopping before warmup cycle was complete. Next morning after overnight cold-soak I had the issue on startup.

Since then I have learned to let the car complete the warmup cycle before turning off car or using EV mode if available for moving short distances. I have not had a problem since and just rolled over 36000 miles.

 

Yesterday morning, ours started pretty loud and shook the car. It was only for a few seconds and then it got quite.

It had sat overnight. It is possible that the previous afternoon it may have been moved a short distance. I am building the garage, and may have moved it 20 yards so no debris would fall from the rafters.

How long does it need to run, for it's warm-up cycle?

It has not gotten 'cold' here yet. Night temps have only been in the high 30Fs.

 

If your going to move the car a short distance try to use the EV mode to prevent the ICE from starting up. If the ICE does start it's hard to say how long to let it run for. One time I moved mine a short distance and the ICE ran for about 3-4 minutes and the next morning when it started it had just a hint of this rough start problem.

 

I normally let mine run until the engine cuts off by itself. In colder weather it will continue to run to try to satisfy cabin temperature setting. In this case I normally lower the cabin temp setting so the engine will cut off when warmup is complete.

Also, if you do get the rough start, floor the accelerator which will increase engine speed and the roughness will stop.

 

I doubt any regular PriusChat member reading the Gen III boards would have forgotten this unresolved issue.

I too experienced it under an incomplete ICE warm up cycle followed by an overnight cold soak. After reading numerous similar postings here, I have always made sure my ICE has completed its normal warm up before shutting it off for any extended period. To date, I have had no further instances of this gawdawful engine behavior.

I am unaware of any recognition or action by Toyota and this problem is obviously still uncorrected given continuing reports here(192.... and counting!). PriusChat participation represents a tiny fraction of Gen III ownership, so undoubtedly this is obviously an extensive worldwide issue.

Especially troubling is the fact that at least nine 2011 Prius owners have now reported this issue here on PriusChat!

If this were a simple or inconsequential issue, Toyota engineers would have already issued a TSB and would have modified the 2011 models coming off its assembly lines.

 

I had a Honda Accord that had the same temperament if one started it cold and moved a short distance and shut down before it warmed up. Next start was usually very rough with missing. Like the Prius ICE solution, just made sure engine got to warm up first even if it meant letting it idle longer. So this might not be unique to Prius?

 

There was also a TSB for the issue and recommended fix, but Toyota sort of swept it under the rug.

I'd be a bit disappointed if my new car had these issues.

 

At this point in time there is no related TSB for the Gen III Prius, nor do we know that any other Toyota model TSB specifically addresses or solves this issue. What we do appear to have on hand right now are a common set of conditions that seem to increase its likelihood of occurring and reoccurring.

This rough ICE start-up appears to most often follow an incomplete ICE warm-up cycle with an intervening cold soak of ~4+ hours). Ambient air temperature may also factor in; but this ICE issue has occurred under a wide range of temperatures. Perhaps warmer ambient temperatures require a somewhat longer cold soak to bring on this rough engine start.

I am unaware of any concrete evidence that Toyota has "... swept it under the rug".

 

Well my 2010 prius with 41,000+ miles experienced rough start for the first time....no comment

 

My solution when it's cold is to power on to ready and "momentarily" floor the accelerator before ICE kicks in. Have not had a repeat since and right at 20K miles now. Pretty sure it's a fuel thing. I just do it out of habbit now like the old days of pumping the pedal before starting in the winter with carbs. Your experience may be different.

 

Add me to this list. It has happened to my 2011 three times since September. Each time it happened it was after moving the car out of the driveway then immediately shut off. After a few hours of sitting, the noise would appear for a few seconds at start up. I will have the problem recorded on my service history when I bring it in next month for the 5,000 mile service.

 

I actually came on here to figure out my gate code/homelink, and lo and behold, this thread was staring back at me.

Just happened to me this morning for the first time (2010 gen III 20k miles). Moved the car yesterday afternoon about 10 feet from one side of the driveway to the other. 16 hours later, worst noise ever on start up.

I won't make that mistake again. Leave it to the amazing prius chat boards to put my mind at ease (ish).

Thanks all!

 

I believe this may have happened to us this morning. Yesterday, I moved our 2011 out of the garage, shut it off and then moved it back in an hour later. This morning, shortly after start up, a Wth moment occurred with unusual engine noise and vibration. It abated a few moments later and has not returned.

After reviewing the threads on this subject it appears this issue is a result of an incomplete ICE warm up.

How does one avoid this issue? If a complete ICE warm up is the solution, how do you accomplish this? What is the minimum time you should keep the unit on?

Thank you.

 

I've had this occasionally too on previous cars under similar circumstances, but not yet on the Prius (only 7500 miles so far).

I expect the cause is a fouled spark plug (at least temporarily). If deposits (unburned fuel, moisture leftover from combustion or another source) is left on the plug, it can short out the spark and cause the cylinder to not fire (and the engine will run roughly and shake). This is most likely to happen under the circumstances described, because the plug didn't get a chance to warm up. Plugs come in different heat ranges (see here: Spark plug - Wikipedia, the free encyclopedia) specifically to prevent either deposit buildup, or detonation (pinging or knocking), but if you don't run the engine long enough to allow the plug to heat up, you may end up with deposits. If they're due to this, the plug will probably clear itself up eventually then the engine will run smoothly again. Changing to a different spark plug probably isn't advisable in this case, since the plug needs to be selected for normal conditions, not repeated cold starts. If people notice this after an oil change, it may be because you started and stopped the engine without allowing it to warm up.

 

Winter is coming. If I need to move my vehicle a short distance, I need to put it in 'EV' mode, for the short distance. Or if it rejects 'EV' and starts the ICE, then I need to let it run until the ICE warms up. I get that.

My question is how?

I move the vehicle, and put it in Park when I am done. Now the ICE starts up. I am done moving it, but the ICE is running. How do I keep it running? Even if I stay in the vehicle, with it in 'Park' the ICE will shut-off in a moment. Obviously it will not be warm when it shuts down.

So how do I force it to keep running?

And how do I know when it has warmed up enough?

 

I'd guess a full minute of running might be enough (through S1A if you want to get technical: http://priuschat.com/forums/gen-iii...-discussion/76501-gen3-warming-up-stages.html).

I've noticed EV might not be available in cold weather (which is where you're wanting it to move the car - I could sometimes have the same wish to just move the car in the driveway). A couple solutions:

Start moving, then shutdown within 12 seconds (before the ICE starts), then repeat. Not very elegant.

If you want to keep the ICE running, turn on the heater. This seems to force the ICE to run to make heat for the heater.

 

Thank you for that link.

Lets say it is below 0C, which means it will not operate in S0. So it will want to go to S1a, but from what I am reading S1a has the ICE running but it is not capable of generating power yet [due to the timing being delayed]. The ICE must run long enough to heat itself up to 65C, before it goes into S1b [and it can begin generating power as well as heat].

This sounds like during the winter we need to:
a- start the vehicle and turn the heater on;
b- wait at least 50-seconds [or some other length of time, for it to get into S1b operation];
c- before we should start driving.

Would a remote car starter be in order? To start the car and give it a few minutes before we go outside.

We normally see 0C starting in beginning of November and continuing to March / April; with a week or two of -28C in mid-January.