engine noise in park while running

Is it the violent shaking at start up, a known issue for which Toyota has yet to find a cure, although a temporary cure is to apply the throttle and it'll resolve.

Or is it a normal engine noise if your wife is one of those Prius owners who forget they actually have an engine?

 

I've also heard intermittent noises from my car in the 18 months I've had it. During my 49k miles, I can average 58 in the summer, and 40 in the winter. The low mileage is likely a result of the cooler temps, which require the ICE to remain on longer in order to provide the heat you are demanding in the car. Could something have gotten stuck under the car somewhere, causing that noise, only to go away again when you check? Please let us know what you find out.

 

Something is off. You're in 0 degree temperature and you're expecting 51 mpg?

 

have both times been right after pressing the start button on a cold car?

 

A hybrid is more sensitive to cold than a non-hybrid. A non-hybrid ICE runs all the time thereby maintaining a constant temp. A hybrid ICE achieves it higher mpg's due to periodically shutting off or running at lower rpms. In cold temps, the hybrid ICE needs to run more often, or in some cases all the time to maintain proper temps and provide heat for the driver and passengers. I garage my Prius so on cold mornings, I turn off the heat and use the heated seats for the first couple miles to let the ICE warm up faster.

 

If the OP is expecting that, it's clearly a bad expectation.

I doubt it got the "basically the same MPG regardless of the season or temperature". If the mileage was low to begin with, then a 10-20% drop is hardly noticeable in absolute mpg.

Please read links at http://priuschat.com/forums/gen-iii...ileage-in-mid-west-winters-2.html#post1216266. Even http://www.fueleconomy.gov/feg/factors.shtml says

and in another tab mentions

Tire pressure when new vs. now?

Besides properly inflated tires, to help improve your winter mileage, you should consider:
- altering your heater use and use of eco mode to avoid unnecessary ICE use to provide cabin heat
- grille blocking
- engine block heater

The first is free. The second is cheap while the 3rd isn't that cheap. Please see http://priuschat.com/forums/gen-iii...-car-in-history-in-winter-13.html#post1249210 (and a few posts that follow) and http://priuschat.com/forums/gen-iii...937-poor-winter-fuel-economy.html#post1215787 re: altering heater use.

If you want fuel economy help, please start a new thread in the fuel economy section to answer http://priuschat.com/forums/gen-iii...-answer-these-questions-esp-if-youre-new.html.

 

i think the problem with the noise is that if the dealer can't duplicate it and it's not throwing any codes, there isn't much they can do. i don't blame her for being upset about it, a strange noise is not something to ignore. as far as the tie in to reduced mpg's, you'll probably have to give it some more time to see what it does. hopefully, someone will see your post who has heard a similar noise. all the best!

 

So it happened twice and you've described the noise as chattering. Some call it banging. Others call it rattling. But I bet it's all the same known problem, the rough engine start for which Toyota has yet to find a cure so you're not alone.

 

I'm putting my money on what 32kcolors says..........

Steve: The next time this happens...have your wife nail the fuel pedal to the floor....see if the noise stops right as she does this. Is so......it's the same noise that many of us have heard.

It happens......Toyota knows about it......

 

Agreed that it sounds like the oft-mentioned rough engine start problem (which I have not experienced, but many have a handful of times). Many (but not all) who have experienced it have noted that it happened after running the car just briefly (eg moving it from the street to the garage, or driving a very short distance) and then letting the car cool off overnight (or more). Was that the case for you as well?

 

Definitely not the case. Can't say I've experienced this yet, but I'm also not yet to 7000 miles, so I am mindful that it can occur at anytime.

 

I own a 2010 Prius III and am having the same engine noise problem when starting the car in the morning. My dealer says car is not trowing any diognostic codes and can't find anything wrong. Car will do this nosie thing on ocaission. Noise usually disappears. However, yesterday morning it did it again, but this time it was really loud. Caution light went on, also a warning came up that said "place car in P position" or something like that. Warning remaining inplace and remained and flashed when I tried to back up. Checked under car for any obstruction and found none. Shut off car and called dealer and spoke to service. When told of the caution light and warning about moving car from P, service man said " that's really strange" and had car towed for service. Tow man disregarded warnings and was able to drive car to place it on truck. No engine noise when restarted, of course, just the warnings. I expect dealer service will call with some news and I will post findings.

 

thanks, i'm curious as to what this could be.

 

An update to my last post about the noise problem: the service technician and I had a good talk about the problem. I informed him that I have been on this site and know that this is a growing problem and he admitted that he has serviced Prius's as recently as last week with the same problem and the outcome is the same: call Toyota and open a case and await a fix. There is nothing more that can be done. Toyota's present instructions are to reset the dash to clear warnings and send car back to owner. Curious about the codes being trown to my dash and what caused them, I was told that in spite of the warnings on my dash, no codes appeared as a result of the diognostic. Why? dash warnings do not always generate diognostic codes. To me that is dumb, but to Toyota that makes sense somehow. This is a lost opportunity to find a cause. Why can't the diognostic machines read these codes? As a result I will never know why my engine has these noise problems. Now, do I really believe that Toyota has no idea what is happening? come on! Look at the ECU chip that is probably at the top of the list of causes. These chips were recalled once already and I think they deserve another look. One coorection: in my original post I listed my Prius as a III, it is a IV, but I don't think that's a concern to this noise problem, but I wahted to present accurate info here. Anyone have any thoughts on this?

 

This happened to me like 5 times went to the dealer and they replaced all the injectors which I knew they were just lost and charging warranty money! after they replaced all the injectors happened to me again twice!, if you talk to any of the Toyota dealers they will all play stupid like they don't know anything!! there are a bunch of complains oit there about this violent start that is not even funny and even videos in youtube!

In my experience listening and reading for months I have heard that the solution is very expensive involving the VVT-i controller and the camshaft and other mechanical parts, so if there is no mayor engine damage Toyota will not release a TSB! better let the car runs instead of spending the money on a mayor recall.

I have observed that this rattle / knocking noise at cold starts happened always in COLD weather and if the normal warm up cycle was interrupted!

Some people have shorted the noise by pressing the gas pedal when happens!!