Audi A4 2001 1.8T Quattro
213K KM
Unitronics stage 1+
Bought from my buddy last year(who moved away now)
Boost gauge installed by him
CEL has been on the entire time I owned the car. My buddy said the stage 1+ probably did it and not to worry about it.
Have used only 93 Octane
Oil change within last 500KM (5W40)

About 3 weeks ago a very loud noise starting occurring during idle:


The noise only occurs when:

1. Under 5KM/h and slowing (as soon as I give it gas the noises goes away)
2. Under 900RPM
3. After driving for 15 mins

Not sure if its related but my battery died (replaced) about 6 weeks ago and from my limited understanding it would have reset the ECU profile?

I'm planning to get a mechanic to take a look and the CEL codes read but if I could just get some general ideas what it might be that would be appreciated.

From my reading and talking to friends it might be:
-Time chain tensioner
-Oil pump dying
-Lifters
-ECU issues

Thanks!

 

Not a lifter tap - if your car is idling, that's too fast unless it's several of them. CCT is definitely possible. Get the codes scanned and post your results though - what codes are stored may easily confirm that. Don't pay a mechanic to do it though - Autozone and other parts stores will scan it free of charge. Post up the codes here, not just the definitions but the actual codes, and we can go from there.

 

sounded like my A4 last year, you would have thought i had a diesel. Turned out to be the Cam shaft tensioner, chain was tapping under valve cover. Replaced it and a new valve cover gasket. Good luck.