NEW!!! Service Bulletin for Engine Knocking at Startup T-SB 0012-10

Mine does it year around on the 2011 and 2012 (2011 is worse). Very infrequent and scares my wife as the whole car shakes.

Got to think it is a fuel related issue while the car is trying to start or something preventing the car from a normal start sequence.
That is one of the reasons I bought the extended factory warranty from Jerry for both cars. If I get 120K I don't care as I never keep a car after the warranty runs out. 50K they go to my daughter and I get a new one. So when re the 15s coming out?

 

I always thought it was a rat or snake trying to keep warm in the engine compartment on those cold San Diego winter nights... now I know.

 

Update! I now know the same thing happens in 85° weather. A couple of times this summer I heard a noise for just a fraction of a second that was the same noise I used to hear when the engine noise occurred. Those times the car started with no other issue. On Monday I backed the car out of the garage, drove it to a neighbor's house (a block) and came back. I left it out all day since I had a project in the garage. The weather was in the 80's and sunny and dry all day. Moved it back in around 7 p.m. On Tuesday, 8/19, my wife started the car to go to work and it was exactly like it was last winter. Just another entry on my log sheet.

 

My 2012 did it this morning. 75 degrees in the garage. Im really getting sick of my prius! It has 42000 miles and has never been impressive. My 07 yaris has 123000 trouble free miles with nearly as good mileage. So monday ill call the dealer and tell them about my prius Diesel!

 

Yes, sunny and warm 80 degrees, moved the car out of the sun into the shade in the driveway (10ft) and the next time I started it, it shakes a little. 4 or 5 secs but I quickly realized I did not let it fully cycle up to temp.

I don't use the fuel additive Heet in summer like I do in the winter so I should of expected it.

I can keep this from happening during the winter with the fuel treatment.

Just for the record this is the 4th time with 61,000 miles.
Still original intake on a 2011.

 

I had this issue occur earlier this week. Our Prius has 65k miles. The car had been sitting for 3 days. 80-85 degrees air temp. Upon start up, the engine knocked violently until we turned it off. +/-10 seconds. We took a short trip around town afterwards with no further incident, but I decided to park it until it was serviced yesterday. I took the Prius in for service to the dealership, armed with the TSB info I found on this site. I explained my experience and the service writer scoffed at me, and went on to later say.....wait for it...."It's completely normal to knock after sitting a few days. the engine management has to relearn how to run the car, my expert mechanic of 30 years and Prius engine expert said so...."
Needless to say I don't agree that this normal. Since when is acceptable for the engine upon startup to knock violently until shutdown? The knocking wasn't going to stop until it was shutdown, how is this NORMAL? If this happened to my wife without me, she wouldn't have known what to do and could this action have severely damaged the engine as a result? As a precaution, I pulled the car from daily use until it could be serviced. Total BS. I've lost my faith in dealer for now.
The lack of care or concern on behalf of the service department is truly disheartening. If there is a published TSB, It's obviously a problem, don't give me excuses, acknowledge the issue, fix it now. The End.

 

Unfortunately the "TSB" won't fix it either.......the only "Real" fix is to trade it for something different!

 

I have been having the same rough start for the past two years. Never mattered what time of year or the temperature outside. You could always rely on it to shake and rattle on start-up. It really scared us the first time it happened, but then I found this thread and it calmed my nerves. Since it's first occurrence we have driven about 50,000 miles without the car ever throwing a code. We now have 120,000 miles. Anyway, my wife went to go to work yesterday and she made it about a mile down the road when the CEL came on. I'm thinking it is a loose cap, but when I plugged in the OBDII reader it recovered codes P0302, P0303, P304 (misfiring on cylinders 2 thru 4).

I keep track of fuel mileage on Fuelly.com and the car is running like a top. Fuel mileage hasn't dropped, no hesitation and it still has get up and go. This leads me to believe it is the dirty IM and/or EGR valve and not something more serious. I need to change plugs anyway, so I was going to clear the codes and drive it to see if it throughs the codes again, pick up a can of MAF cleaner, clean the MAF sensor and the IM. Anyone see any reason to take it in and test for other issues?

 

Or clean the egr ports

 

@defrankond:

I'm very curious about your comment, above, re EGR ports.

I suggested quite a while back that it might be an EGR valve problem, but don't know whether anything was ever proven. However, I see there is another thread which discusses rough-running problems caused by a sooted-up EGR valve manifold port, but that problem seems to be quite different, happening when the engine is already warmed up and running, not at start up.

Are you suggesting that the severe knocking at cold start is definitely related to a dirty EGR port or a faulty EGR valve?

 

Yes I am. In fact in fact I will even go this far. I recently traded my 07 off with 98k miles due to engine knocking. The stealers hip told me the engine needed to be replaced and I not having the money to do that I traded it off on a 2010. After a week I went back to the dealer my 2007 was sitting on the lot with the service order on the seat. The engine wasn't replaced but noted in the comment section was cleaned EGR port valves for engine knock. The car ran flawlessly. Needless to say I was pissed that I was taken advantage of by the dealership and by the time the manager got back to me the car had sold.

The issue is the valves get carbon build up and oil spray sucked into them and over time they start to get blocked resulting in the engine knock so famous that we hear now. With the thinner synthetic oils it tends to stick and cake up over time. I am sure if you look at the egr port you will find that they have a lot of buildup and cleaning them will resolve the issue. It seems that it starts happening around 40-40k miles. The harder the engine is pushed the sooner they will clog.

 

I doubt the valve is faulty. My guess is it is just sites up and not allowing gasses to pass

 

Pissed! I Bet!

But this is all news to me. I have an '08. Only real problem so far was it required a new water pump at about 86,500km. Fortunately, under Dealer Warranty. I know that the G2's don't commonly have the G3 Cold Startup Knocking problem, but I didn't know they could still have EGR-related knocking problems. So, many thanks for the Heads Up on that.

Again, very interesting. I would debate the exact failure mechanisms with you though, if I may?

For a start, the thinner oils should not make much difference, if engine "oil control" is adjusted to suit. What I mean by that is that if the oil control rings, piston and ring groove holes are suitably redesigned to suit thinner oils, there should be no appreciable difference in oil consumption (as is confirmed in this forum), so the time it takes to clog up the EGR system should not be affected by oil viscosity. However, I think you hit the nail right on the head when you said "synthetic oils".

For every advantage, there is usually a disadvantage. The beauty of synthetic oils is their great resistance to breakdown under heat. They don't "burn" ("cook", or decompose) to varnish and tar and all those other nasties nearly so easily. So, with synthetics, one doesn't seem to get the same brown and black crud sticking on the underside of the piston, in the ring grooves, and generally kludging up the inside of your engine.

The downside of this appears to be that when they do go through the combustion chamber, because of their heat resistance, they don't then burn as cleanly or as thoroughly, and maybe that's when they form high temperature deposits. Because the EGR valve is only taking a small percentage of the exhaust gas flow, it's going to be much cooler than the exhaust valves, ports and manifold, so if anything is going to deposit partly burned synthetic oil byproducts, that would be the likely place. It also makes sense that the harder the engine is pushed, the sooner the EGR will clog up, because the harder it's pushed, the more oil it's going to burn. Plus, no doubt there is a "sour spot" (opposite of a sweet spot) temperature, at which the burnt oil products tend to deposit more readily in the EGR system. Likely, below certain temperatures, the oil doesn't break down very much, so provides more lubrication and cleaning to the EGR valve. No doubt, if the temperature is high enough, the oil will burn off (as in exhaust valves), but at temps somewhere in between, it becomes tarry and sticky. That place has gotta be in the EGR system.

That sure makes sense to me, in terms of clogging up the EGR system.

However, it doesn't really explain the G3 Cold Startup Knock. Unless, as I suspect, what's happening is that the EGR valve only gets partly clogged, and remains crippled for a much longer period. It makes sense that the EGR valve is slightly open almost all of the time the engine is running. So, if kludge builds up on it in its slightly open position, it may then be unable to ever close properly. This may not be a problem 99% of the time, and may possibly even go completely unnoticed.

However, a slightly open EGR valve provides exactly the path I proposed at great length earlier in this thread, which allows the damp air that's left sitting in a cold exhaust system after a short run, followed by a few hours sitting, to waft through into the intake manifold. The condensation that forms inside the intake manifold as a result, is what gets sucked straight into the engine at the next startup, sloshes over one or more spark plugs to cause the short term misfiring, shaking and knocking so well documented as the G3 Startup Knocking Problem. (Maybe, since the EGR valve is presumed to be sitting (stuck) slightly open, it's even sucking water that has condensed inside the whole EGR valve and piping, if not from the exhaust manifold itself?)

I like this theory! (I'm so modest as well... )

But the theory is worthless without some testing. Who has a car that has this Startup Knocking problem very badly?

Who has a friendly mechanic who would pull your EGR valve and make a careful inspection?

Some possible questions:
{Is the valve dirty, sitting slightly open and unable to close?}
{What oil (type, brand, grade) has been routinely used in the engine?}
{What is the regular driving pattern of the vehicle?}
{What fuel type and brand is normally used?}
{Are any fuel or oil additives used?}

 

I concur with you good sir and raise my hat . You went into greater length than me but my thoughts exactly.

 

They deleted the TSB for the USA. Canada still has it. It is a weird situation.

 

Checked also, Canada SB also obsoleted.. Hopefully this is a good sign for a repair

 

Now all bulletins are missing, HOWEVER there is a new Tech Tip out asking all technicians to contact Tech Assistance if they have the issue for further instruction.

I suspect there is a new bulletin coming, especially because they were investigating possible headgasket failure.

 

Had an 8:30 am oil change Appointment this past Monday. Got in the car, belted up, pushed start and the rumble and shake occurred at start up. Lasted less than a second or two. Like it knew it was going in for service and had to remind me that it happens now and then. It had been a pretty good while since the last rough start episode. I did mention it to the service manager as I was signing in. I've mentioned it to him a couple of times before. He just kind of shrugged.

It's a known issue. MPG has been great. Took a long trip from Maine to Florida and back a couple of weeks back. The Prius was flawless during the 3,400 mile trip.

Got my Oil changed. No charge. Manager said it took too long. I hadn't noticed since it was a nice day and went out for a walk a couple of miles down the road to a Dunkin' Donuts for coffee. They had the car a couple of hours, maybe a tad more.

Maybe the Manager felt badly that they can't fix the rough start issue?

 

Having not read he entire 37 page thread, what's final word on this problem?
It hapened the first time to me this morning, California 54 degree night.
Sounded like someone threw a wrench in the works. I shut it off immediately, popped the hood and startedit again, same shaking and rattling, but then started and ran smooth all the way to work...

2010 Prius II with 40K miles

 

The state of this issue as of 11/10/14 (to the best of my recollection):

The TSB (Technical Service Bulletin) that had been issued for this has been retracted by Toyota.
Some people who had the TSB-defined service performed reported the problem eventually came back.
One workaround at startup is if it starts doing the shake/rattle is to push the accelerator all the way which helps get the revs up and eliminates the roughness, you can release the pedal after a short time of warmup.