[CU2] To all the new Euro Auto owner out there!!!!

[jbowly]

With a lot of letters to the media about the same engine noise we are all experiencing finally Honda have caved in and given me an answer. It is as follows... Software fix is reputedly available mid February

Dear John, we appreciate that you are concerned about the presence of an engine operational sound as it detracts from your overall enjoyment of the vehicle and we wish to again reassure you that this condition will have no impact on performance or engine reliability. We have been working closely with the technical division of Honda Corporation in Japan and following extensive investigations we can confirm that the condition you are experiencing is not that of “pinging” which is known within the industry as “pre-ignition”. The condition that you are experiencing is a combustion sound taking place after the programmed ignition, namely a “post combustion noise”. As this condition takes place after the programmed ignition and with the piston on its downward stroke, there is no detrimental force or impact within the engine in your vehicle. Therefore your engine has not sustained any damage and we are happy to offer you a guarantee on the engine while you are the owner of this vehicle as a way of reassuring you of our confidence that no wear or damage is occurring to the engine or associated components.

We trust this advice from the manufacturer clarifies the matter.

Regards
Joe Gelsi
Customer Relations Manager
Honda Australia Pty Ltd

[Type R Positive]

Post combustion noise?
I wonder what it is?

[SPQR]

Post combustion noise?
I wonder what it is?

Honda's answer reminds me of the news report I heard on ABC radio many years ago just after the earthquake in Kobe, Japan. They were reporting on a CNN broadcaster who was interviewing an American citizen who happened to be in Kobe during the earthquake. The interviewer asked him all sorts of questions about his earthquake experience and, even for the last dumb question, the interviewer demonstrated that he wasn't listening to the interviewee. The interviewer asked him if he knew what caused the earthquake and, after an appropriate pause, the American on the spot said "A Howard Stern fart"....

In any case, the bloke from Honda is partly wrong because pinging, the characteristic metallic sound, is the same as knocking which occurs after the spark plug has fired and is caused by a pocket of mixture exploding away from the ignition front whereas, pre-ignition is caused by a hot ignition source in the the cylinder that pre-ignites the mixture before the spark plug gets a chance to do it at the right time. Pre-ignition is not likely to occur in a fuel injected engine.

His advice that the sound is post combustion is correct but it is pinging or knocking but not pre-ignition as he said.

Both conditions can cause damage to an engine.

[lousli]

Or just buy a manual...

Interesting, they must change more then the name when they ship the Accord to North America. My wife and I both have 09 6MT TSX/Accord and we both have the same problem as do most 6MT TSX's. Good thing it isn't engine knocking, or so they say.

[Type R Positive]

In any case, the bloke from Honda is partly wrong because pinging, the characteristic metallic sound, is the same as knocking which occurs after the spark plug has fired and is caused by a pocket of mixture exploding away from the ignition front whereas, pre-ignition is caused by a hot ignition source in the the cylinder that pre-ignites the mixture before the spark plug gets a chance to do it at the right time. Pre-ignition is not likely to occur in a fuel injected engine.

Inefficient combustion? Doesn't sound like Honda.....
ECU tune FTW!

[SPQR]

Inefficient combustion? Doesn't sound like Honda.....
ECU tune FTW!

No it doesn't. But I've said it before: I think that the cause is the higher compression ratio of the CU2 engine compared to the CL9 engine. As Honda has said that they are working on a software fix, they'll probably retard the ignition timing (changing the compression ratio is not feasible) and/or adjust the VTEC in the hope of encouraging a more consistent charge mixture.

All measures that could potentially reduce power and torque.

The Honda bloke is wrong to describe pinging as pre-ignition: They are two different conditions as I had previously described. He has correctly described a post combustion event which is pinging/knocking but not pre-ignition. Pre-ignition of the charge by definition happens before the spark ignition. To say that a post combustion event does not lead to damage is not necessarily correct as it could increase pressures in the cylinder.

[Type R Positive]

No it doesn't. But I've said it before: I think that the cause is the higher compression ratio of the CU2 engine compared to the CL9 engine. As Honda has said that they are working on a software fix, they'll probably retard the ignition timing (changing the compression ratio is not feasible) and/or adjust the VTEC in the hope of encouraging a more consistent charge mixture.

All measures that could potentially reduce power and torque.

11:1 cr is sweet F.A. in the scheme of things.
Is it the cause of the problem? I doubt it very much.

[SPQR]

^^^ 11:1 compression ratio is considered a high compression ratio (up from 10.5:1 in CL9). Engines are more likely to ping/knock with a high compression ratio.

Some interesting info at Wiki: http://en.wikipedia.org/wiki/Compression_ratio


Some quotes form Wiki:

"A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency. High ratios place the available oxygen and fuel molecules into a reduced space along with the adiabatic heat of compression - causing better mixing and evaporation of the fuel droplets. Thus they allow increased power at the moment of ignition and the extraction of more useful work from that power by expanding the hot gas to a greater degree.

Higher compression ratios will however make gasoline engines subject to engine knocking, also known as detonation and this can reduce an engine's efficiency or even physically damage it."

"Due to pinging (detonation), the CR in a gasoline/petrol powered engine will usually not be much higher than 10:1, although some production automotive engines built for high-performance from 1955-1972 had compression ratios as high as 12.5:1, which could run safely on the high-octane leaded gasoline then available."

[Type R Positive]

the thing is it's not ping.

[SPQR]

^^^ The Honda bloke described it as "post combustion noise". That's what Honda reckons it is. That is exactly what pinging or knocking is.

Some more info at: http://en.wikipedia.org/wiki/Engine_knocking

And some quotes from Wiki:

"Knocking (also called knock, detonation or spark knock, pinking in UK English or pinging in US English) in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise time in the piston's stroke cycle. The peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive. It should not be confused with pre-ignition (or preignition), as they are two separate events."

And;

"Pre-ignition (or preignition) in a spark-ignition engine is a technically different phenomenon from engine knocking, and describes the event wherein the air/fuel mixture in the cylinder ignites before the spark plug fires. Pre-ignition is initiated by an ignition source other than the spark, such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events."

[denot]

guys, i'm looking to get one of the CU2 soon... so one thing is still making me confused... is this problem appear on all the CU2 model? or is it for specific model and build date?

thanks heaps

[Type R Positive]

guys, i'm looking to get one of the CU2 soon... so one thing is still making me confused... is this problem appear on all the CU2 model? or is it for specific model and build date?

thanks heaps

Just random. Seems 100x more prominent in the Auto's.