ZVW30 rough engine starts

It occurred to me once back in January 2010, after the car had been stood for a few days in cold conditions (about -2c day, -8c night).

When reported to my dealers, they suggested it might be a dodgy coil pack. Whether they replaced it or not, or updated software is unknown, but the problem has never occurred since.

 

My one rough start happened on a cold January day after I moved the car in my driveway and shut it down while running after less than a minute the day before. My engine shook and knocked for several seconds while I sat there surprised at what was happening to my brand new car. I took it to the dealer and the technician found no error codes and it started and restarted normally. The dealer said when they jockey new cars around in their lot in cold weather they sometimes experience similar rough engine episodes that clear up after a few seconds. I don't know if Toyota uses a cold start injection of additional fuel on cold startup but that may explain rough running similar to a flooded engine that clears up after the excess fuel is burned off. I now always let the ECU run at least through its initial warmup cycle before shutting down in cold weather and have had no problems since. PS This is my first post after enjoying all the great info on these forums for almost a year now.

 

I have had the same experience as solarfan twice. Both times were on a cold morning after moving the car a short distance the night before and stopping the engine before it completed its warmup cycle.

I was fortunate that I had read about this on PC and knew to turn the car off and then restart it. The second time it happened I had recently read a post by Tumbleweed where he suggested pressing the accelerator when this happens. I pressed the accelerator the second time and the engine leveled right out.

I know now not to stop the engine before it completes its warmup cycle. I also elect to move the car in EV mode when moving short distances. I have not had this happen since.

 

No rough starts.
But I have noticed the tiniest bit of shaking a few times when the ICE turns off right after stopping at a light.
Wonder why that happens.

 

As I reported in another thread, I too experienced this ICE anomaly after backing our 2010 Prius a short distance down our driveway, shutting it down, and then restarting the car about 48 hours later(yesterday). When this rough engine start occurred I didn't notice any warning lamp indicators and the engine smoothed out in 3-4 seconds.

Today, after reporting this incident, my local service manager said he doubted he'd see any meaningful codes from my experience and also doubted if he could reproduce it. I told him that I'd read well over 150 PriusChat reports about this anomaly and he said he hadn't yet witnessed it but agreed to let me know if a TSB was issued.

Update: FWIW, when this anomaly occurred I was in ECO mode.

 

The poll isn't very specific about what kind of rough start this is about.

I've read about others having considerable noise and strong vibration on startup on rare occasions. I have never experienced that.

The single incident I report here was a start last month where the engine ran very poorly for a couple seconds, then quit. It produced neither the load noise nor heavy vibration I'd heard about earlier, but a distracting conversion kept me from noting enough detail for any report. Upon shutting down and restarting, it ran normally. No repeat since.

 

I voted once per month although it hasn't happened that often, that was the closest choice.

I seems to happen if I have to start the car for a brief period, to relocate it for example, then shut it down without warming it up. After that I may get the rough start syndrome the next morning when I start it up. It has never happened when the engine is warm. It seems more prevalent in cool weather.

With my car it seems rather severe, knocking and shaking of the engine. As I have mentioned in other rough start forums I can stop it by simply putting the throttle to the floor for a second or so, when the engine speed increases by a couple of hundred RPM it stops the knocking and shaking. Jdcollins5 has tried this also, as mentioned above, and it seems to work with his car too.

It may also help to start the engine by pushing the throttle down as soon as the ready light comes on instead of waiting the 12 to 15 seconds for it to start on its own. I have been doing this when starting the car while cold since last spring and have not had the problem when I start it that way.

 

Now its 13:10 existance:no existance. My 2 incidents didn't seem severe. Is this something people think could be a real problem, and not just a software glitch? Both times the car had been sitting for days if that helps.

 

I think it would also be useful to see how many people have had a rough engine start following a warm-up cycle that was cut short - as so many people have reported just moving the car around the driveway prior to the rough engine start. I posted a companion poll to this effect; vote early and vote often!

 

happened to me once since ive had the car (just short of 2 months)

Car had been parked for 10+ hours, got in, started it up. It started quietly (electric) then almost immediately (within a second or two) the engine kicked on. It was louder then normal, running hard, and running so rough the car was literally shaking.

I turned it off, popped the hood. Nothing looked amiss so i got in (leaving the hood up) and restarted the car. Engine kicked on within 5 seconds and this time it was running normally.

Temperatures were in the high 60's, low 70's.