Author Topic: Knocking at Idle...  (Read 451 times)

Jayt43

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Knocking at Idle...
« on: November 23, 2021, 06:29:03 AM »
I've noticed - over the last few days - that my Crosstar produces what sounds like an engine knocking noise under the following conditions...

1) In Park Mode engine running, handbrake on...
2) Engine running as heating is on (so not in EV mode).
3) Instrument cluster does not show battery charging mode (i.e. it just shows the engine with no arrows / directional information going to any wheels).

The noise sounds like an uneven idling / knocking but also a bit like a loose fan that's not spinning on its bearings properly...Hard to describe but not altogether pleasant. Under load the engine is totally fine. 

Perhaps there is absolutely nothing wrong and this is normal and a feature of operation. But it's bugging me. Anyone else hear the same noise under those conditions?

 
« Last Edit: November 23, 2021, 06:31:06 AM by Jayt43 »

sportse

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Re: Knocking at Idle...
« Reply #1 on: November 23, 2021, 06:41:06 AM »
Iíve had it occasionally, I put it down to a bad batch of fuel initially.

It didnít sound like it was running smoothly, but perhaps itís normal and just to do with the generator part at idle as itís not a usual car engine.

Kremmen

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Re: Knocking at Idle...
« Reply #2 on: November 23, 2021, 06:50:56 AM »
I've not noticed it
Let's be careful out there!

Jayt43

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Re: Knocking at Idle...
« Reply #3 on: November 23, 2021, 07:10:35 AM »
It didnít sound like it was running smoothly, but perhaps itís normal and just to do with the generator part at idle as itís not a usual car engine.

Yes, I'd like to think the same, but it sounds a bit rough (taking into account Honda's engineering excellence).

I doubt it's the fuel, I only fill up with Shell V-Power.

sportse

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Re: Knocking at Idle...
« Reply #4 on: November 23, 2021, 07:58:14 AM »
Iím the same, only V power- perhaps at idle when the generator isnít charging the battery it just rattles a bit when not connected.

Car drives fine, itís only occasionally at idle it does it.

Lord Voltermore

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Re: Knocking at Idle...
« Reply #5 on: November 23, 2021, 03:52:53 PM »
Could it be due to a colder  ambient temperature ?

 I read somewhere (possibly on here) that because the engine is not driving the car directly  (at least not at first)  it doesnt need to be  as smooth and tractable as a normal car for cold starts .  Honda take advantage of this  to run the engine with slightly altered timing  and a leaner fuel mix, which warms it up quicker and uses less fuel. 
A trade off between rougher running and the benefits.   It may still happen to some extent when the engine is giving out heat
Sorry if its too long winded. I failed my brevity exam at school. Ran out of paper.

Jayt43

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Re: Knocking at Idle...
« Reply #6 on: November 23, 2021, 04:38:21 PM »
Could it be due to a colder  ambient temperature ?

 I read somewhere (possibly on here) that because the engine is not driving the car directly  (at least not at first)  it doesnt need to be  as smooth and tractable as a normal car for cold starts .  Honda take advantage of this  to run the engine with slightly altered timing  and a leaner fuel mix, which warms it up quicker and uses less fuel. 
A trade off between rougher running and the benefits.   It may still happen to some extent when the engine is giving out heat

I think you'd be spot on, except for one thing. I wanted to record the knocking noise on video but, when I tried this afternoon, the ambient temperature was around 9 degrees as opposed to 2-3 degrees each morning when I've heard it. Nothing to be heard. Therefore, so far so good with your explanation.

The only thing is, even in the morning when it's present, that's after a 3-4km run to school. I turn off the engine, drop off the kids, return to the car and then, while it's idling, the noise returns. I would have thought that run alone would put enough heat into the engine to essentially make it a (warmer) re-start.
« Last Edit: November 23, 2021, 06:50:26 PM by Jayt43 »

Roman

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Re: Knocking at Idle...
« Reply #7 on: November 23, 2021, 07:04:06 PM »
I've noticed - over the last few days - that my Crosstar produces what sounds like an engine knocking noise under the following conditions...

1) In Park Mode engine running, handbrake on...
2) Engine running as heating is on (so not in EV mode).
3) Instrument cluster does not show battery charging mode (i.e. it just shows the engine with no arrows / directional information going to any wheels).

The noise sounds like an uneven idling / knocking but also a bit like a loose fan that's not spinning on its bearings properly...Hard to describe but not altogether pleasant. Under load the engine is totally fine. 

Perhaps there is absolutely nothing wrong and this is normal and a feature of operation. But it's bugging me. Anyone else hear the same noise under those conditions?

Have this sound  often when use 95 RON -  (our 95 RON is bad for this engine) stopped knocking when used 98 RON gasoline, now this knocking back aigain as i filled 10l of 95 RON to almost empty tank.

Lord Voltermore

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Re: Knocking at Idle...
« Reply #8 on: November 24, 2021, 12:22:50 PM »
A few thoughts that may provoke debate .  I am not an expert. They may not be relevant. I may be wrong on any of them .

I believe Honda   takes measures to ensure faster warm up such as changing timing and it could include not charging when the car is stationary .This may be  more as a fuel saving measure . Extra load would tend to  produce more heat.

At 2-3c the effect of air passing through the radiator will be considerably colder due to wind
chill.  .  The engine ,radiator coolant etc may not be fully warmed up in 3 km or so. 
 
Modern cars dont just measure the engine  temperature when metering the ideal fuel/air ratio.  They also monitor the ambient air temperature and rate of flow of air into the engine. Because colder air is denser and more concentrated.    So the car 'knows' its cold and may continue with its special measures longer than you expect even when the engine may be warm.

Because the engine often runs relatively slowly  , or not at all , compared to the speed of the car  significant wind chill might cause the radiator coolant to become  locally very cold . This could lead to problems when the engine restarts.   To minimise this its  possible the car may use an electric  coolant pump , or an engine driven one that  couples or uncouples  thermally or electrically.  I cant find any technical information on whether this is the case,  but it makes sense.   It could keep warm coolant circulating, or stop it circulating  when thats better.   And  reduce load on the engine when its not needed  .   (If you havnt got one Honda you heard it from me first. I want paying  ;D)
 In warmer weather thermosyphon circulation may sometimes be sufficient .
A bit like radiator  fans evolving from constant, to thermo coupled to electric.

If such a system is used  this may be the noise you are hearing.  Either the pump running or  a coupling freewheeling or something. A further thought here.  Air con compressors  uncouple in this way and sometimes rattle. Could a change in temperature/climate control settings  or activity  be  the cause?

Petrol is less volatile in colder weather. This could lead to rougher running. And any ethanol makes this worse.  E10 is probably not a problem but I know that in cold climates  E85 (85% ethanol) is changed to something like 70% ethanol in winter  - but still called E85

I think the formula of petrol is changed in winter  so its more volatile and vapourises better.(This is definitely true with diesel, but also true with petrol I think, at least in some countries. )
Cars running poorly when cold  at this time of year might be because  you ,or the filling station ,still have summer grade petrol . Things may improve next fill.
« Last Edit: November 24, 2021, 12:32:04 PM by Lord Voltermore »
Sorry if its too long winded. I failed my brevity exam at school. Ran out of paper.

Steve_M

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Re: Knocking at Idle...
« Reply #9 on: November 24, 2021, 12:44:20 PM »
Or is the noise you are hearing from the eCVT?
Information provided to dealers from Honda regarding eCVT knocking noise when cold:

When starting the engine from cold, you may hear a groan/rattle for about the first minute, or when the engine decelerates.
This noise is caused by gear tolerances when the generator inside the transmission is not underload. This noise is considered normal in operation and the eCVT transmission should not be changed for this symptom.


Roman

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Re: Knocking at Idle...
« Reply #10 on: November 24, 2021, 11:09:20 PM »
If cause of this noise is eCVT that spins without load this can be from this part
on 12:15 John Kelly demonstrating flywell with permanent safety clutch that present in our eCVT (if all e:HEV transmissions identical) if i understand right this springs in clutch assemble when engine  not loaded can make noises that can be identified as engine knocks.
When i hear this noise it`s feels like misfires and engine shakes when i hearing this noises (mayby this dampers can't compensate in this case), and i must say when i one time started car after it not used for  2 days and outside temperature is hot (about  +40 noontime)  this noise and shakes of engine
were even worse for first minute or two.
P.S. All firs year i used only 95 RON gasoline, sometimes this noise appeared more often, sometimes it was almost not heard, I still think that the quality of the fuel affects the appearance of these knocks.

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