Badhabbit

Hey guys. My 2008 S8 (Euro spec) developed a loud clicking noise from the engine bay. It sounds like it is coming 4 inches behind the driver side hpfp, and it intensifies with rpm. I do not have a stethoscope, so I can't try to isolate it this way at the moment.
I scanned the car and the only code is P0441 which is the purge valve. Naturally, I replaced it, but the clicking persisted. I also disconnected it for a minute, but that made no change at all.
Apart from the clicking, the car runs fine - smooth idle, no misfires. The intake flaps have been deleted by the previous owner and tuned out.
Now, in my mind the possible culprits are hpfp, injector or lifter. I have attached a video of the car making the sound while moving.
I would really appreciate it if someone has any ideas on the issue.

Badhabbit

I was just told it might also be an exhaust manifold leak. Does this sound legitimate?

Badhabbit

After some spirited driving and several pulls to redline, the ticking is gone, and the cars works as it should. I honestly have no idea what this was. Has anyone ever overfilled the v10 with oil? Could this actually cause a ticking noise? I'm not saying that I have done it, I'm just wandering if there is a chance that I have overfilled it by accident.

florinb92

On my Q8 I have the same ticking sound but I can't get rid of it lol
did your came back or it got "fixed" permanently ?

Badhabbit

For me it was coming and going for a while until I decided to dive deeper. Turned out to be a worn out injector that was making the sound. Keep in mind the sound is almost identical to lifter tick, so it could also be that. Does your car have any accompanying symptoms? When do you hear the ticking?

trilis

It could be washer under the injector, please try to change

Badhabbit

If the washer under the injector is making the noise, would it be fair to assume there would also be compression leaking, as it would not be seating properly? It might also cause play in the injector.
You can use VCDS to check the fuel trims and see if there is compensation for some actual issue with the injectors.

dvs_dave

Throw some injector cleaner in the tank and drive it hard in manual mode for at least 10 miles with the rpm over 3000+. That should get the oil flowing and fully pressurizeany lazy lifters, and clear out any sticky injectors.

The old Italian tuneup.

Badhabbit

I wouldn't disagree with this, it is always good to stretch the legs of the engine, but this definitely did not work for me. I even soaked the injectors in cleaning solution without any effect. They were basically shot. If this knocking is from the injectors, chance is that you will have to replace the faulty ones.
Other possible culprits are HPFP, lifters, chain guides, evap purge valve.
Are you able to locate roughly where the sound is coming from?