Rough Engine Start? Knocking Noise At Startup? There May Be Hope Yet...

It has to do with interrupting the warm up cycle of the engine.... if you start the car and move it a short distance and shut it back off, the next time you start it the engine sounds like it is going to fall out. Rattling, clunking, knocking violently and eventually quieting down.... Somebody claims the intake manifold needs to be replaced and will resolve the problem but not sure if it takes care of it 100%..... There is some Toyota TSB on this apparently.

 

I had a car last year which had this problem and it was solved by this video after trying everything including TSB's
I hope it helps someone out there with the same problem.

 

Mine made this noise today on startup too and was rather embarrassing. Will try to add some fuel injector cleaner today and see if it helps any otherwise I'll be dropping the car off at the dealer.

 

How many miles on her? Any symptoms before today in regards to rough start / idle?

 

Just about to hit 50k. I've heard this noise 2 or 3 times before in the past 6 months or so but was never this bad. Luckily my dashcam cam on and started recording before the engine started so I have some footage to show the techs. Other than the noise I heard once today the car runs normal. :/

 

Yes

It seems common in the Prius , Toyota has an tsb on this but try injector cleaner first. If that didn't help then try taking the car to a place where they have fuel injector cleaning machine and make sure their spray pattern is uniform , this is what solved my problem in my Prius not the tsb .. good luck

 

I've been having this shaking/rattling now for over two months. Took it to Pep Boys and they said it was a transmission issue and tjhey don't work on transmissions. need to go to the dealer. Went to the dealer - Cylinder #1 misfire. Replaced Coil and plugs. $650 USD. Two days later, same shaking. Researched here and found Toyota letter citing issue with EGR valve and that we do a free EGR replacement. Asked the dealer if he was aware of this and he said no but offered to EGR service free. Two days after fix, same shaking. I brought it back in and next he told me that engine needs an overhaul due tiny head gasket leak allowing small amount of coolant into the cylinder and therefore not allowing that cylinder to combust properly until after a few seconds of having coolant "blow out" through exhaust. Definitely lost faith in the dealer through this experience. just had a different mechanic flush the coolant system and am not attempting to add "Head" stop leak however there is no radiator cap and they recommend feeding "Head" into the hose entering into the radiator (not use the reservoir tank). I used the top hose on the tank to feed into the radiator (hope this was correct!? seems to split also to somewhere else). If this stop leak stuff doesn't work, then I'll try some industrial fuel injector cleaner I can enter into the gas tank. I'll let folks here know if the stop leak worked. All comments welcome. thanks.

 

How many miles?

 

Not allowing a full warm up cycle will cause this issue. Never move the car a few feet and then turn off the motor. Allow the motor to turn off first and then shut it down. This works!

 

Follow-up: OK. It's been 5 days since flushing the coolant and introducing "HEAD" stop-leak and I'm happy to report no more shaking or CEL. Still early but keeping my fingers crossed. BTW, engine has 140K miles on it (2010). Have done little maintenance to it over the course except for religious synthetic oil changes every 8-10K miles and whatever recall/fixes the dealer notices me. Also, I have 3 Priuses (Prii?): 2005, 2010, and new 2017 Prime Advanced. Time is valuable to me and for minimal effort (less than I should for sure) these cars provide the best value/reliability. Took a lot of scorn and laughter when I purchased my 2005 in 2004. Now with so many on the road globally i'd like to think they now see me as a visionary (even though I know they don't...just wishful vindictive thinking on my part). Will give another update in about a month. If all is well I'll add a good injector cleaner (never introduce 2 fixes at once - won't know which one worked). Knock on wood.

 

I'm having same issue with my 2010 prius , a rough startup with a huge noise like hammering under good, dealership said is normal in prius, that there is nothing on recalls about it, has anyone heard any updates?

 

Orenji, You have the problem solved. It's quite that simple, just don't allow the car to start and then shut off after a few seconds. If it starts let it do it's thing and shut off on it's own.

 

Welcome to Prius Chat .

How many miles on your Prius? How long have you had the knock? Does your Prius consume oil?

The more info you can provide us with, the more answers we’ll be able to give .

Keep us posted .

 

What about if you have only two bars left and then ice kicks in just as you parked in place and press power button to turn engine completely off after 6 miles of driving and fully warmed up? Is that a must avoid thing als0 thanks.

 

I don't have this particular issue with my Prius, but noticed the engine starts a lot smoother with the climate control off. Try it.

 

I'd vote no. Never considered this, only the cold shut down issue. I've had ONE knocking episode, and that was after a cold shut down.

 

I mean engine is at fully operating temp but right when hv needs recharging from ICE with 2 bars, i press power off half second later. ICE kicked as I depressed the power button, not that I intentionally cut ICE off carelessly.

 

Let me join in this thread. I started having this issue a couple months ago. It had gotten really cold with those artic blasts. Just at around 146k miles my car made this loud rattling noise. Eventually the CEL came on after a few rough start ups. Dealership visits with my TSB letter to have the cold start up issue addressed, of course had to pay for a couple of the parts. Issue started up again not even a 100 miles of driving it. Took it back gave it back 2 days later and happened again that evening. Well, took it back again , they wanted to keep it for a week and gave it back. I drove it 130 miles and the CEL is back and rough starts and it's not even as cold as before, even in 60s it did it. So now the question is, how much of this run around should I do? It's very stressful.

 

Which "couple of parts"? And the TSB letter is for the EGR system?

 

@danlatu has a theory and is convinced an Oil Catch Can emptied regularly can resolve the knock before it causes a head gasket problem. There are a couple of threads discussing this.