Engine Knocking (twice) at Startup - Anyone Else Experience?

I have had it happen about twice. Real subtle to where I was wondering if it happened at all. Once it lasted about 5-10 sec and was really rough but smoothed out.
The way I figure it, if something is really wrong than likely it was eventually fail. At that time Toyota will fix it, their dime. Meanwhile I am not worried about it.
Peter

 

Do a search on ROUGH START. I think there are other threads possibly about it. It seems to be infrequent but don't know of any fix at this point.

I believe the post is "Rough Engine Start" http://priuschat.com/forums/gen-iii...troubleshooting/70128-rough-engine-start.html

 

http://priuschat.com/forums/gen-iii...troubleshooting/70128-rough-engine-start.html

 

Something very similar happened to me. I bought my 2010 V Prius on November 9th and 2 days ago with less than 1500 miles on the ODO I turn off the car and all of a sudden a hard clunking noise came from the engine.
It never happened when I turn on the car, but this is the second time it happened when I turn it off.
Anyone knows what it might be?

 

It was mentioned that the same thing happens as stated above. The MG trys to position the engine for the best start.

 

Ok, I hope this is the right thread I am posting to. I'm very SAD!! and stressed. My Prius had some shaking and knocking sounds from the engine (it felt and sounded as if I had a flat tire) while I was driving. We turned off the power at a stop light. Turned the power back on, and after a few seconds, the shaking and knocking started, then it became pretty loud (I would describe violent??) then the check engine light came on. I had it towed to the dealer and they are looking at it. =( =(

For background info, I live in hawaii so no temperature issue (always nice and breezy). I park at a slight incline, front end facing down. Last night I backed into my driveway (front end facing up). When I started the car this morning, (I can't recall the exact warning), I put it into Drive, but it said "When in Park position, shift to P" or it may have said "Shift to P". So I press the "P" button, then I put it in D, then the same notice came on (may have been 2 or 3 times). I kept pressing "P". then I put it in Drive and drove up the incline and down the road. about 1 minute later, the knocking and vibration as described above started. And there is sufficient gas in the tank.

 

Anyone with any ideas or has this happened to anyone??

 

Sounds pretty bad. Heard of it at start ups and shutdowns but never while running. But it is in good hands now... they will fix it.

 

I often hear dealers say (not just regarding this issue) "It's normal--they all do that...". But is it detrimental to the engine? From my knowledge (albeit limited), knocking isn't good.
Just my take.
Tim

 

That is probably true but we don't know if in fact the knocking is from the ICE itself. The Motor/Generator MG spins the ICE with the values open (no compression) prior to ignition to bring oil pressure up. If for some reason all things are not align, potentially some opposing forces could produce the knock. Of course I am just speculating but the HSD is really a different beast and applying conventional wisdom doesn't always work.
Sides, if something blows up... it will likely be covered under warranty.

 

Agh it happened to me this morning. Cold start - minus 4 c last night and 2 inches of snow (that's cold for here!). Got in, started her up and knock, knock, knock almost like missing. Stopped it and started it again and smooth as a baby. It did sound like a big end knock but then reading the above I guess it isn't. Oil is all ok and car only at 5500miles.

Do I bother my dealer or just see how it goes?

 

This is a known gen III issue, as far as I understand. There are many people on the PC reporting this behavior - just look around the threads. The dealers have been clueless so far... May be a firmware issue. But it seems to be an inherent design flaw, not a random problem.

So, if I were you, I would report it to the dealer just to let them know, but would probably not take any further actions right now. Letting them check the car would probably only be a waste of time and money, as most likely they won't find anything wrong and will play it down.

 

Ok, got a call from the Dealer. if anyone wants to know, the service guy told me that the 2010 Prius has 4 ignition coils. 1 of the coiles short circuited, which caused a misfiring, which resulted in the vibration and loud knocking. The part is on back order so we will see if I get my car back in working order.

 

Hope they fix this by the 2011 model.

 

That would do it, but should have also tripped a misfire MIL almost instantly. I don't think most people are getting a MIL are they?
MIL = Malfunction Indicator Lamp, or most people call it a check engine light

 

Everything according to most dealers is normal until the car is out of warranty. They get a LOT more money for a repair from you than they do from Toyota, plus I'm sure there is more paperwork and questions to answer for a warrantied repair.

 

Listen while it is impossible to really know if Person A's engine knock is the same as Person B's, my advice to anyone experiencing repeated or significant engine knocking or noise on start up or shut down on a new vehicle, would be to take it to the dealer and insist they investigate. IMO waiting until it fails or something blows up, is not a wise choice.

Even if they tell you it's "normal", which IMO it shouldn't be, but even if it is, or they tell you it is normal, you want it documented ASAP.

Knocking, vibration and noise is indicative of stress being put on parts somewhere. If this becomes an issue or leads to a serious failure, I'd want it documented through a dealer and Toyota that I noticed an issue and did everything I could as an owner to get resolution before a major failure.

I don't really trust it when a service department comes back on something like this and says "It's the normal operation of the vehicle". I'm just going to site what has been said by many posters in relationship to other issues on this site, if it's normal, then seems there are a LOT of 2010's that aren't experiencing this symptom, and if they can have a quite smooth starting engine all the time, then I want a smooth quiet starting engine all the time.

Whether it's a intermittent acceptable behavior of the engine or not, I surely wouldn't ignore it and wait for if/when you might have a major failure.

PT Cruisers had the reputation of burning a lot of oil, when owners started to complain in mass about oil consumption Chryslers response was simply to say the oil consumption amount of the PT Cruiser was within acceptable parameters. IMO a cop out, hiding a real problem.

If Toyota wants to say their brand new Beltless engine in their 2010 Prius's are operating "normally" when they rattle or vibrate excessively on start up, then I want validation from Toyota that they recognize it is happening and are offering no solution. That way you don't get stuck as an owner defending why something horrible happened to your engine and why didn't you notice any rough running before the failure?

Bottom line, document, complain, insist...even if nothing is done, at least it's in the system.

 

I have not experienced this on the 2010, but DID experience this on my GEN I Prius. I was told that it had to do with the MG1 alignment at startup.

It may have done it about 3 total times over the 3 years I owned the Gen I Prius, but was obviously not detrimental to the engine in any way.

I have NOT experienced it at all in my 2010 Prius V. And it's been colder now with Winter.... so I don't think it's temperature related.

From some of the posts I read, it appears to happen on a short start of the car to possibly move it quickly and then turn off. On restart it appears it happens more frequently to those posters.

DHMAK explained this in the earlier post called 'hogging', and that's what the dealership at the time in Maryland told me it was on the earlier Generation Prius.