I would think getting one for a fleet car would work the same. I saw individuals in the postings testing and ordering. Its in preorder status anyway at the moment. Posted via the PriusChat mobile app.
I'll see what Toyota says when I bring it in for another recall issue. I've noticed it doesn't occur in cooler weather, only when it's 80+ F out.
I did a quick search as I recalled seeing info on hotter weather. Do you use Top Tier gas and have you checked the EGR valve as well? Prius III engine knocking at high torque low RPM (solved) | PriusChat Posted via the PriusChat mobile app.
I thought the Prius hybrid ICE didn't have to run at high torque..... Ever! Isn't the whole idea that it is always running at its optimal speed and never gets strained as a direct transmission geared ICE would.
That might be an objective but not fully implemented. In the real world it is hard to achieve that, especially when a significant burst of power is required. The batteries and electric motors aren't stout enough to do that by themselves.
Torque output is a function of load not engine speed, but yes, these engines rarely operate near peak load. Pinging / knocking due to pre-ignition is most likely at LIGHT loads under lean conditions, because that is when combustion and cylinder temperatures are highest; hence pre-ignition. It is also where EGR flow is the greatest, so a deficiency in that system can actually induce the condition.
Interesting theory. But why does it almost NEVER happen that way ?? Maybe it's because at higher throttle more air/fuel is allowed into the cylinders, thus increasing the effective compression.
The compression ratio has nothing to do with this. Pre-ignition is nothing more than fuel igniting BEFORE the spark plug lights it. That is a function of cylinder temperature, peak cylinder temperatures occur during LEAN conditions. Now, lean means relatively less fuel for a given amount of air, or conversely, relatively more air for a given amount of fuel. The most common cause of pre-ignition under load are LEAN conditions due to faulty sensors, typically the MAF/AMM is reading incorrectly.
I saw where someone had a clogged EGR valve and it pinged only in hotter temps Posted via the PriusChat mobile app.
Reading exactly what is written, however, has everything to do with it. It is the actual total compression on a given stroke that varies the instantaneous temperature of the fuel mixture and has EVERYTHING to do with the mixture igniting too soon. When you open the throttle more under load, MORE fuel/air goes into the chamber on each intake stroke. That results in MORE actual compression during the compression stroke. That is what causes the ping to show up more when accelerating or climbing a hill. AND......the higher the designed compression ratio IS, the quicker the above shows up. If you have an engine designed with a really low compression ratio, it is almost impossible to get a pre-ignition knock under normal circumstances.
Sam, time to educate yourself. You do not understand the finer details of the internal combustion process.
Time to put up or shut up. What exactly did I say above that you think is inaccurate ?? Be specific. And you have absolutely no way to know what I "understand".
Sam is clueless and wants to argue with him. Just put him on ignore and he'll go away. Its awesome. Posted via the PriusChat mobile app.
When you can't come up with an intelligent response......then just give up altogether. But somehow twist that around in your own mind so that it is a "win". Priceless.
Doesn't the effective compression go up with more throttle because of the VVT? In other words it's an Atkinson cycle at light throttle but an Otto cycle with heavy throttle? Pixel XL ?
I agree but the postings het weird when somebody is responding to him and there is no indication of that. Looking at the post numbers in a thread and noticing there are gaps is the only way I have found.
A follow up to this issue: it's still unresolved. I recently had it in with Toyota for a combo meter repair ($$$), and I specifically asked them to investigate my engine ping while they had the car. It's been getting more frequent and even happens in the cold now; unless I use premium. I picked up the car and they said nothing was wrong. I find that VERY hard to believe. I pushed, but didn't get anywhere since it was a Saturday right before they closed. I may try calling them back about it and asking them to look at it again for no charge. On a side note; I recently drove my parent's 2007 Prius, and quickly noticed they also are experiencing severe engine ping. Later that week, I was in a parking lot and heard a 2006 / 2007 Prius drive by with undoubtedly a lot of engine ping. This must be quite a widespread issue far too few drivers even think twice about.
