97 E420 ticking sound on hard acceleration
 

No ticking at idle (so it does not seem to be the oil tubes). It almost sounds as if it was pinging from low octane as on old cars, but I put 93 octane in it and I think newer cars compensate for that by changing the timing. Any idea what could cause this? Is there some type of sensor?

Get the codes and see if there is a Knock Sensor fault code.

would the check engine light not be on? can this code be read by a regular obd2 scanner?