[CU2] Noise when aircon is on and accelerating from stop

[JimA]

Hi all, I own an Accord Euro 2010 model that I'm very happy with. I have noticed however that when I accelerate from a standing position whilst the aircon is on, that a noice can be heard briefly. The noise sounds hollow, that is, similar to when you tap an empty plastic bottle with a metal spoon.

I've checked the water reservior for the radiator and i'm losing a little water everytime I check i.e once a month. But I've been told that It's normal to lose a little water. Hoping someone can confirm this.

The noise heard whilst accelerating from a stationary position with the aircon running is brief, that is, for around 2-3 seconds. Hoping that someone can shed some light on what may be the problem.

Kind Regards
Jim Athan

[Type R Positive]

Hi Jim, that sounds like the 'post combustion sound' mate. There's heaps of threads on here about it, and Honda says it's no problem at all. What fuel are you running? Try a tank of 98 and see if the noise goes away.

[Fredoops]

another CU2 victim with the "Pinging"

[JimA]

Thanks for your response. I've read the post combustion / pinging threads, however I think the noise I hear is something else. I'm assuming this because my vehicle is a May 2010 MY11 build vehicle. It's my understanding that the post combustion issue was addressed with this batch of vehicles and beyond.

The noise I hear tends to only last for 3 seconds, characterised by 2-3 succesive sounds - like tapping on plastic bottle, or something under strain. It's only heard shortly after I accerlate off the mark. As a continue to accelerate throught he rev ranges, I don't hear this noise again. Also, as mentioned earlier, I only hear it whilst the aircon is on.

I intend to take it in for service at Honda in early August. If I find out what it is I'll let you know the outcome.

Kind Regards
Jim Athan

[HunterZero]

Some CU2 model Euro automatic owners are still noticing the post-combustion sound even after the fix. The sound is reduced but not eliminated in some cases. If you haven't done so already, try running the tank down, and filling with 98 RON fuel either BP Ultimate 98 or Caltex Vortex 98, and see how you go. Avoid E10 fuel like the plague.

- HZ

[jay2]

I think I might got the pinging issue too :(

Mine is a MY12 euro lux (auto) and the issue still exists, I thought they would have been fixed when it rolls out the plant!

At first I thought is the aircon kicking in and releasing the gaseous sound. Then this morning I drove around with the aircon off and notice the faint but audible metallic clicking/rattling sound (similar to rushing fluid through a pipe strangely) as i accelerate lightly and the gear changed from 2nd to 3rd.

I am running Caltex Vortex 95 currently though.

Has there been a solid fix for this issue out there yet? I read people sent their car in for the fix and the pinging resurface weeks later.
Also Honda claimed that this post ignition is not detrimental to the engine and we should just leave it as it is. I am confused now.

Please adivse...

[praja6]

Jay, I use BP ultimate since brand new for my accord euro my10 and i never hear the ping issue. I don't know if you use ron98 fuel it may hide the ping issue? Its interesting to hear the facelift euro got the ping issue too, i thought they rectrified the issue ages ago.

[nxn75u]

Bring the car back to the dealer and tell them the issue. I think that they do is resetting the ecu or reprogramming it. I have heard cases from a friend where they have to replace the whole new unit of ecu into the car.

[jay2]

Hey Raj, I myself is shocked and surprised too that the MY12 exhibits the pinging! What a disappointment. I committed on the purchase knowing Honda has already provided a fix for the issue...and would expect all new euros thereafter would be ping free...sigh...

Anyhow, I will try the BP Ultimate fuel option first. Still have 3/4 tank of Vortex 95 to drain...

nxn75u, thks for the suggestions. I will bring back to the dealer when the RON 98 option fail. However, I read that after the ECU programming, the car could become sluggish or the fuel economy decreases.

[praja6]

Jay2, i think you better talk with the dealer now as well as per Nxn75 suggested.. As per Honda the recommended fuel is ron95 and it shouldn't ping.. For me from the beginning(apart from the tank dealer filled with), i started using BP ultimate and don't want to change it. If i use ron95 fuel, i may have ping not sure.. BUt i really don't know what fuel dealer(rick damelian @ sydney) filled the tank when i bought the car and i never had ping in that as well..

Good luck

[antony]

I usually use 98 Vortex in my MY11 Euro,and have never had any pinging issues........

[nxn75u]

Fuel might be one of the reasons causing the engine to 'ping'. If i remembered correctly, there is a sticker near our gas tanks saying 'E10 suitable'. To me it is just absurd having that sticker on where the brochure clearly says to fill up at least RON 95.

Main reason for the pinging is as quoted from carsguide:

"But the good news is that we had an issue, and there is a counter- measure. It's an electronic or ECU issue, not a mechanical issue."

"The other thing to remember ... is that this is doing no harm whatsoever to the engine. We guarantee the engine will have no ill effects. It has also had no effect on performance or the fuel economy."

http://www.carsguide.com.au/news-and-reviews/car-news/honda_accord_engine_problem_being_fixed

Still bring it back and demand fix asap. Mine was brought back and was good from then on.

[jay2]

I am now running on BP Ultimate RON 98 fuel and the pinging still exists!

It's not a fuel problem guys and the MY12 euros are still plagued with the engine issue. Beware.
Going to see servicing on Wed.

Will keep all posted.

[praja6]

Jay2, its good to go to service dept and see and they will change the knock sensor and ECU as per most mention in some previous post.

I thought BP ultimate or 98 RON fuel mask the problem. I haven't heard ping at all. That means so far my car doesnt have the ping issue atleast for now. Who knows in the future.

[vasu]

Hi Guys
I had CL9 before and now having CU2 MY12 Lux..and never heard this pinging noise....so what is this noise exactly and when does it occur..couple of other friends have CL9 too but they've never experienced this noise too..

[Tai]

Vasu from my sources within Honda the the late model CU2's had its block redesigned and did not have the pinging issues the previous models had.

But of course Honda Australia Won't admit that.

They had ecu updates which did not help with the pinging issues on the previous models.

[buddah51au]

I have no issues with this problem on my MY12 CU2, & it was only a very minor intermittant problem on my MY08 CU2. The software & knock sensor updated fixed it

[jay2]

Buddah51, even when you run RON95 fuel, you have no ping issue?

Vasu, it's a very faint metallic clicking sound that seems to come from the front of the dashboard/air vents (of course it's from the engine in front) and you have to listen very intently to catch it.
One have to drive with air-con off and all windows up.
Pick a moderate slope/incline and apply light to moderate acceleration to bring the car RPM to the 2000 - 2500 mark (at least for my Euro) and try to maintain that acceleration. You will of course hear your normal engine sound coupled with a faint metallic clicking/rattle that last maybe 3 to 4 seconds.

Do a search on this forum and many have already replied. AFAIK, I could be the first to report ping for the MY12.

[buddah51au]

No pinging issues at all. The engine in the MY08 - MY11 was a K24Z3, the MY12 uses a K24Z6, what the differences are I dont know but 1 would expect there would be some internal changes.

I have mostly used 95 RON in both my CU2's, on the odd occasion I have tried 98RON I have found no difference at all. My last tank in my MY12 was Vortex98 & the fuel consumption on that tank was fractionally worse than the previous tank of BP95 driving the same roads & conditions. I can see no advantage at all in spending the extra for 98RON.

BP95 - 983kms / 64.06 Lts = 6.52L/100

Vortex 98 - 1002kms / 66.05 Lts = 6.6L/100

[HunterZero]

No pinging issues at all.

BP95 - 983kms / 64.06 Lts = 6.52L/100

Vortex 98 - 1002kms / 66.05 Lts = 6.6L/100

Yeah, but do you ever put your foot down buddah, or do you always drive in septuagenarian conservative fuel saving mode? ;)

- HZ

[HunterZero]

I am now running on BP Ultimate RON 98 fuel and the pinging still exists!

It's not a fuel problem guys and the MY12 euros are still plagued with the engine issue. Beware.
Going to see servicing on Wed.

Will keep all posted.

Jay, how many kms on the car?

- HZ

[buddah51au]

Yeah, but do you ever put your foot down buddah, or do you always drive in septuagenarian conservative fuel saving mode? ;)

- HZ

I drive at slightly above the posted speed limit, if i need to get around something I just do it. I don't baby the car, nor do I thrash it, a few times on each tank when the engine is hot I run it up to 6500 - 7000 rpm.

However, if I am travelling country roads at night I do take it very steady, I guess this is due to a phobia I have about wildlife as a result of hitting a horse at 120kph many years ago.

[jay2]

HZ, my current mileage is 1850 Km.

Came back from the dealer and here is the verdict for my engine ping. I need you guys input on it.

Went with senior mechanic to test drive and yes he acknowledged that there is ping. He called it the post detonation symptom experienced on all faulty CU2 ver.1.
He claims that its no drama as Honda already certified that post detonation does not cause any detrimental damage to the engine.
Also if this was his Euro, he would not want to remap the ECU (as in replace the knock sensor and ECU software fix) as performance and fuel efficiency will be affected.
Being an MY12, it would already have the latest ECU software upgrade/fix.

His advice to me was to put in the best fuel I possibly can for the car (which is RON98) and when the ping occurs under load, just accelerate more to get out of the ping zone!

After this, many questions and confusions came to my head and I try to walk myself through.

1. If Honda said it's not damaging to the engine, why did they provide this knock sensor and software fix??

2. Why would a proper fix affect performance and fuel economy??

3. Why did this engine pinging problem affect only some Euros and not all??

4. Why doesn't engine computer flash engine error on dashboard when pinging occurs??

Can only conclude that the fix was for the first gen of CU2. The ping in the first gen could be quite bad and the knock sensor is really faulty.
As buddah had mentioned that the MY12 uses a new engine block, I reckon the fix could not be applied as a result.
On one hand I hate to here the noise every time I accelerate and knowing something is not right with the engine. On the other, I do not want the half baked fix to alter the nice throttle response and fuel economy of the car...!
Guys, should I demand for the knock sensor and ECU fix or leave with it??!!

Nevertheless, the service manager was nice in that we raised a PQR (can't rem what that was) with Honda and also lodge a formal complaint with Honda Australia for my MY12 CU2 engine ping.
He said that Honda Australia will look into and advice further.

Will keep all posted on Honda Australia reply.

[jay2]

Just went to check, my MY12 has the K24Z3 engine instead of the K24Z6!!

Can the fix be applied then?

Hey Buddah, after you apply the fix to your previous Euro, do you notice and change in performance or fuel efficiency? Guess you might be the best person to ask since you always try to get the best mileage out of the euro :)

[buddah51au]

Just went to check, my MY12 has the K24Z3 engine instead of the K24Z6!!

Can the fix be applied then?

Hey Buddah, after you apply the fix to your previous Euro, do you notice and change in performance or fuel efficiency? Guess you might be the best person to ask since you always try to get the best mileage out of the euro :)

There was no noticable difference in performance or economy. My MY12 has an engine prefix of K24Z6, it is an early build date 0f 02/11, so pre earthquake in japan. Australian compliance of 08/11, so I cant understand why you would have the K24Z3. what is the build date of your car?

[jay2]

Interesting, where can I locate this car build date information?

[buddah51au]

Lift up your left hand windscrren wiper & you will see the build date, Australian compliance is on the lower "B" Pillar inside the left front door.

[jay2]

Buddah, you won't believe it, my car build date is March 2011 and is having the K24Z3 engine...

YOu have an earlier build date then mine and using the new engine... something is missing...

[buddah51au]

I have spent hours searching for the differences between the K24Z3 & Z6 engines ..... no luck so far. Both our cars are pre japan eathquake disaster.

[buddah51au]

Buddah, you won't believe it, my car build date is March 2011 and is having the K24Z3 engine...

YOu have an earlier build date then mine and using the new engine... something is missing...

Major Dealer Fuxx UP - My rego papers & service book state a K24Z6 engine prefix. I have just physically checked the engine number on the block & it is a K24Z3. I need to get this sorted ASAP.

[Fredoops]

I have spent hours searching for the differences between the K24Z3 & Z6 engines ..... no luck so far. Both our cars are pre japan eathquake disaster.

Make a post on hondatech forums.