1.8L starting rattle, knock, events

Again, as I said, this is for emission regulations. More advanced ignition timing tends to result in higher emissions. At temperatures above 122 - 154 F, EGR will also kick in when you're actually driving the car (intermediate or heavy loads); so, it's a moot point that you don't see the EGR kicking in when your car is idling. It's all to control the emissions and reduce pinging (detonation), and remember that pinging means more engine damage and more NOx emissions. Also remember that too much ignition-timing advance results in pinging if the EGR is not on (high combustion temperature and/or low-octane fuel = detonation). And the EGR cannot be turned on until the engine-coolant temperature reaches around 122 - 154 F because it would result in a stalled engine or poor drivability.

 

I wasn't saying that EGR is related to the rattle. Remember, you were asking why there is a curious ignition-timing-advance behavior. In answer to that, I was saying that you would see the advance in the ignition timing when the coolant temperature becomes high enough for the EGR to be able to be turned on (without stalling the engine or affecting drivability) when you put the engine under load. Sure, it's also advanced even when the engine is not under load, but this is also typical with other engines. In my 85 Corolla for example the vacuum advance on the distributor will advance the igniting timing 8 degrees when the engine is at idle -- high-vacuum condition.

But the ignition-timing advance you see is not happening right when you hear the rattle, is it?

 

I purchased my 2010 Prius V 2 months ago. Currently have 3100 miles. I have had this knocking noise occur. After reading every single post I thought I should share my experience.

I had to move our vehicles around late in the evening. I moved the Prius with it on running for about 2 minutes. The next morning I had to be at work at 5 a.m. The temperature was 38 degrees. The noise only lasted about 10 to 15 seconds. I have not heard it again.

Frank

 

Bob,

I think this rattle is being caused in the valvetrain, probably the intake-camshaft gear as Toyota says or some other valvetrain component. It may be being caused by a mismatch between the thermal-expansion coefficients and geometry of matching components (such as the timing chain and the intake-camshaft gear). This might be why you are only seeing it occasionally, at very specific temperatures. I think it has little to do with the engine controls if at all.

Since you're into engine controls, I looked up how these worked in my 85 Corolla. The main idea is the same and these conventional carbureted engines make it easy to understand.

There are two devices that control the timing in my carbureted engine, the vacuum advancer and the governor advancer. The vacuum advancer has a subdiaphragm and a main diaphragm.

The subdiagrahm: Advances timing by 8 degrees at idle/low throttle or high altitudes (mountain driving). High-altitude compensation is necessary because when the O_2 levels in the atmosphere drop, air - fuel ratio becomes richer and ignition timing needs to be advanced for better drivability. Note that at some high-altitude locations, the octane of the gas sold is lower. In this case the high-altitude compensation system wouldn't work without making the engine ping, unless you stick with 87 octane. Also, advancing the timing at idle and low throttle increases drivability.

The main diagrahm: Advances timing up to 30 degrees or so if the throttle opening angle is more than the so-called R-port location. The advance depends on the intake-manifold vacuum -- the more the vacuum, the more the advance. You would see a lot of advance at low throttle, low load but only if the throttle opening is more than at the location where the R port is.

Governor advance: The timing is advanced more (up to 20 degrees or so) with increasing RPM, according to the RPM. Although, at very high RPMs, timing is slightly less advanced.

So, if could you plot the throttle opening angle and manifold absolute pressure along with your ignition-timing advance, I bet you would immediately see the correlation.

Finally regarding EGR: The purpose of the EGR is not to cool the exhaust gases. I know you're thinking about thermodynamic efficiency (e_Carnot = 1 - T_C/T_H) but this is not what it does. In fact it does exactly the opposite -- it decreases the combustion temperature by cooling the combustion chamber with inert exhaust gases, which lowers the thermodynamic efficiency a little bit. But this is necessary in order to reduce the engine wear (by reducing pinging) and to reduce the NO_x emissions (which are caused by high combustion temperatures).

EGR is only turned on at coolant temperatures above a certain value and at throttle opening more than a certain angle. When the EGR is turned on, its volume is modulated according to the exhaust pressure (higher pressure more EGR) and throttle opening (when the throttle opening is more than at the location where the R port is, full EGR, between the R port and the EGR port, modulated EGR, less than the EGR port, no EGR).

 

EGR also prevents combustion gasses which get past the piston rings from being vented directly into the atmosphere.

Not sure why the discussion about ignition timing, the noise is quite likely valvetrain related. At idle, you could run a TON of ignition advance and not have issues.

 

That's positive crankcase ventilation (PCV), not exhaust-gas recirculation (EGR). To reduce HC emission, crankcase blow-by gas (HC) is routed through the PCV valve to the intake manifold for combustion in the cylinders.

To reduce NOx emission, part of the exhaust gases is recirculated through the EGR valve to the intake manifold to lower the maximum combustion temperature. (This also decreases engine pinging [caused by high combustion temperatures and/or low-octane gas] and the resultant engine damage.)

 

Oooops, my error.

 

I got a new 2010 in mid Sept, 2010. I have about 3850 miles on it. We have had a recent cold snap in the Wash. DC area for the last week. Two days ago I drove the 12 miles to work in the morning at about 23 deg. F. About 9 hours later, when I started the car to go home, as the engine started (about 30 deg. F), it ran very rough with a loud clanging for about 15 seconds. This is the first time I have ever had this experience. We are using winter blend gas in the DC area now. Brand is Shell, octane is 87.

 

I have had it happen 4 times, Larry

 

This rough start is a real problem. It now has happened to my 2010 with 6900 miles on it 8 times. I am dropping it at the dealer today. They will try to duplicate the problem in the morning. It only happens when it is cold. 10 deg this morning in Green Bay wi. It happened 4 times this morning before it smoothed out. Larry

 

Had you reached full operating temperature before shutting it down the night before (or whenever it was)?

Unfortunately, I am willing to bet you with very high odds that they cannot duplicate this tomorrow, that's the problem with it nobody has that I've seen come upon a way to consistently duplicate this.

 

i really dont think its the gas at fault

 

Toyota already has a fix for the problem.

It's apparently being caused by a design or manufacturing defect in the intake-camshaft gear, and, wow, those cams are hitting the valve stems like a hammer when it happens!

 

Thanks for link. it doesn't say 2010 Prius, though. I find this strange that it still appears almost invariably only after a cold shut down. And I've had it in quite warm temperatures (summer morning) and not in much colder temperatures (freezing or less).

 

They are virtually the same engine. The only part number in the valvetrain for Prius different than for the Corolla is for the exhaust-camshaft VVT-i controller in the Corolla vs. the simple sprocket in the Prius (no exhaust VVT-i in the Prius).

 

Interesting stuff.

 

Here is the culprit -- the intake-camshaft VVT-i controller (simply known as "gear"). The problem is that this particular part is Made in China or Made in USA, instead of Made in Japan:

13050 GEAR ASSY, CAMSHAFT TIMING
Replaced by: 13050-0T011
Manufacture notes: MADE IN USA
13050-0T010
2009.04-2009.07
2ZRFXE.. ZVW30
$172.93

13050 GEAR ASSY, CAMSHAFT TIMING
Manufacture notes: MADE IN USA
13050-0T011
2009.07-
2ZRFXE.. ZVW30
$172.93

13050 GEAR ASSY, CAMSHAFT TIMING (NOT AVAILABLE)
Manufacture notes: MADE IN CHINA
13050-0T022
2009.04-
2ZRFXE.. ZVW30
--

13050 GEAR ASSY, CAMSHAFT TIMING
Replaced by: 13050-0T011
Manufacture notes: MADE IN JAPAN
13050-37012
2009.04-
2ZRFXE.. ZVW30
$172.93

Note the Prius-assembly dates and part country of origin for the different versions of the part.

So, what is happening is that the original Made in China or Made in USA intake VVT-i (variable valve timing) controllers are of poor quality and they are failing under certain conditions. The failure is resulting in incorrect valve timing, which is detrimental to your enginee. When the valve timing varies in an uncontrolled manner, the cams are hitting the valve stems like hammers, causing engine damage.

If you're seeing this problem, it's detrimental to your engine and you're experiencing engine damage. So, have your intake VVT-i controller changed ASAP!

You might want to give Toyota a call and find out which part was used in your car. The problem only happens in early-production models (Prius 2009/04/xx - 2009/07/?? and Corolla 2008/01/xx - 2009/07/??). The culprit parts are 13050-0T010 (Made in USA) and 13050-0T022 (Made in China). The good parts are 13050-0T011 (revised Made in USA) and 13050-37012 (Made in Japan).

Here is the information (Page 49) on how the VVT-i works in the Prius/Corolla engine.

 

Yeh, that's the sound of your new engine getting old well before its time.

It's funny, one listen to the video and it was immediately obvious that there was an abnormal valvetrain issue. I'm glad we're past "it's nothing to worry about" and into the "giant red type" stage.

Thanks for the info.

 

Yes, you were exactly right, Pinto Girl. You're one of the knowledgeable people in this forum.

Recall the intake VVT-i controllers in 2009/04 - 2009/07 Priuses and 2008/01 - 2009/07 Corollas, Toyota!