Hey Guys,

My audi has had detonation in the past, it was very quite and sounded like a arcing spark plug (but loud enough to here from inside). I'm trying to find out WTF this extremly loud noise my engine is making.


I check the codes and ignition coil and cam/crank sensors are on the radar.


Is it possible for detonation to be scary loud?


Nick
97RS

I've heard detonation make a car sound like a diesel. similar things could be rod knock. change your oil and look for metal filings.

Edit: pull your spark plugs too and check them for damage.

One day last week, I was driving a buddy's car and, in the middle of a WOT pull, it sounded like someone threw a handful of gravel on the hood. Scared the shit outta me. It wouldn't make boost after that.

I thought it might be detonation, but it turned out I had blown a a couple off the intercooler, the water injection feed line out of the intake, and the MBC into the fan. Scary shit.

Wish I could say more. :shrug

Thanks for the replies. I replaced the bearings already. No shavings in the pan and the pistons (from the plug hole) look fine as do the plugs themselves. It's so loud that it's hard to hear where it's coming from. Nothing at idle but I do feel a little vibration in the clutch pedal that is simultaneous to the sound.

I dont want to pull the head, but I prob need to. Having my bro in law come give his thoughts early next week if not tomorrow.

thanks again.



Nick
97RS

quick thought, do you have the cover on your timing belt? if you do, pull the inspection cover and see if one of your pulleys has taken a crap, the belt should be way loose. when mine gave out it sounded horrible, never missed a tooth so there was no CEL but it bounced around in the cover like a mofo making a ton of noise at anything above idle

The TB is fine, but thanks for the suggestions.

After a bunch of research. It may be the output shaft bearing in the transmission. The result is so loud that it's hard to tell where the hell it's coming from.

I've had problems with this tranny before and it sounds like this may be the cause. Does anyone know a way to troubleshoot this without ripping out the tranny and checking the bearing? I dont want to pull the bellhousing off if there is another way. What about checking the shaft and bearing from the backplate?

I see a bunch of old posts from 02, but the info is just that they are replacing and not why.

Thanks for any new info, it's much appreciated.

Nick
97RS

Detonation sounds like rocks in a coffee can. Shake it really fast.

thx for the responses... I've posted a new thread in the transmission section.




Nick
97RS