[Euro] Engine tappet noise

[EuroDude]

@Billzor, you cant really hear it when in the cabin, especially when the windows are up.
If you lift the bonnet while the car is idling, you can hear the tappets and injectors tick away a few times a second. The sound sounds like a coin tapping on metal.


@TypeG, 5000km is too soon for loud tappet/injector noise, you are probably hearing the normal ticking noise honda engines make. Unless the factory did a dodgy adjustment.

[aaronng]

I already recorded a video before I started washing my car. My tapping noise comes when cold and warm, and only at idle. When you rev the engine, the tapping either disappears or is drowned out by the revving. Converting the vid now. Any suggestions for a host?

[EuroDude]

Photobucket can host videos, dunno if its free or not~
http://www.photobucket.com/

[Matell]

I believe those who've suggested the injectors are dead right.

A remote reason for my assumption of this is back when I was playing AJ and we had the gloriously laid back job of water purification the metering pumps which in essence aren't much different to fuel injectors and deliver precise dose's of various premixed chemicals made this same 'clicking noise'.

It makes perfect sense if you think about it. How do the injectors fire a controlled amount of fuel?

All they are are electronically controlled valves. An electronic pulse sent from the ECU energizes an electromagnet which moves a plunger that opens the valve allowing the pressurised fuel to escape and become atomised via the nozzle profile. The longer the pulse, the longer the vale remains open and the more fuel is released.

The reason it's so audible when at idle is only a small amount of fuel needs to be injected, therefore the electronic pulse from the ECU is immensely quick, meaning the electromagnet is only charged for a fraction of a second, causing the plunger to snap open and return closed via spring pressure resulting in the plunger smacking against the closing face within the injector. The impact produces the 'tick'. I think that’s a simple, yet thorough enough explanation.

One could further validate this crudely by noting that when doing a compression test there is no ticking. The tappets are in motion during this test, although I will concede not at the same velocity as when at idle.

You could also find out if you get a CEL by intentionally disconnecting one of the injector cables when at idle and obviously note the change in ticking. Do that at your own risk!

[aaronng]

^^ Great info. But why does the sound vary in loudness when the injectors used in all the Euros are the same model?

[EuroDude]

Because its the tappets making the louder noise.
Its confusing because the tappets sound similar to the injectors.

Well thats my theory at least

[aaronng]

Try this link. See if you can dl it. The video is in xvid (avi)

http://www.yousendit.com/transfer.ph...AD16272C74EEF9

[Matell]

^^ Great info. But why does the sound vary in loudness when the injectors used in all the Euros are the same model?

Fuel air mixture, quality of fuel, age of injector, idle tune setting.

A difference in both fuel quality, and the fuel air ratio, how you've just been driving the car etc will cause the ECU to seek out a more appropriate point on the fuel map. The only way this is translated through to the injector is slight variations in the amplitude, frequency, and wavelength of the pulse. This will inturn correspond in a variation of the electromagnetic charge, which translates into a difference in the velocity of the plunger, and hence the energy of the impact. More energy=more noise, less energy = less noise.

You should be able to figure all that out, you're an intelligent enough guy, and no that's not being condescending

[Matell]

Try this link. See if you can dl it. The video is in xvid (avi)

http://www.yousendit.com/transfer.ph...AD16272C74EEF9

That works, and it's no different to mine. I had an injector service done at the 80,000km and it hasn't changed.

You can also verify it by taking off the injector cover and placing your hand on an injector. You can feel a pulse, that when you concentrate enough coincides with a ticking noise.

[EuroDude]

Played the video and it sounds similar to mine except I think the tappets sound louder and more busy.

Was that when the engine was cold?

[aaronng]

Fuel air mixture, quality of fuel, age of injector, idle tune setting.

A difference in both fuel quality, and the fuel air ratio, how you've just been driving the car etc will cause the ECU to seek out a more appropriate point on the fuel map. The only way this is translated through to the injector is slight variations in the amplitude, frequency, and wavelength of the pulse. This will inturn correspond in a variation of the electromagnetic charge, which translates into a difference in the velocity of the plunger, and hence the energy of the impact. More energy=more noise, less energy = less noise.

You should be able to figure all that out, you're an intelligent enough guy, and no that's not being condescending

Was wondering, because Euros both older and newer than mine are quieter... I've tried resetting the ECU and do the idle learn procedure, but it does nothing to change the injector noise.

BRB. getting food.

And yes, the engine was slightly cool. About 55C on coolant temp.

[Matell]

Was wondering, because Euros both older and newer than mine are quieter... I've tried resetting the ECU and do the idle learn procedure, but it does nothing to change the injector noise.

BRB. getting food.

And yes, the engine was slightly cool. About 55C on coolant temp.

I notice it with the engine both hot and cold, and it was still there after the adjustment at 40,000km.

If you want to try to feel the pulses so you can settle it in your own mind, you may find that the pulse of one is carried to the other via the fuel rail. In that case if you have a stethoscope (or improvise one) you should be able to isolate the noise from one specific injector.