Engine Knock
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Audiworld Junior Member
Joined: Dec 2008
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not sure...it's pretty subtle. I think left side. Bringing it to dealer this weekend. Maybe bad sensor ? Still under CPO warranty for a few more months so figure I'll have them take a look.
AudiWorld Member
Joined: Oct 2009
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From: Willow Springs, IL
If you're under warranty the dealer should be able to connect their VAG tool and watch for knock during a test drive. If they see excessive knock, then there's a method they follow to diagnose the problem. Without showing any Service Engine light information, you might just have a bad tank of gas.
It's true you have knock sensors to de tune the timing, however, if you jam on it and actually HEAR knock that's too late -- real engine detonation. The sensors can only react and do so much.
I recommend driving slow (no WOT hits) until it's resolved.
It's true you have knock sensors to de tune the timing, however, if you jam on it and actually HEAR knock that's too late -- real engine detonation. The sensors can only react and do so much.
I recommend driving slow (no WOT hits) until it's resolved.
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Joined: Oct 2001
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From: SF Bay Area, CA
I'll be the contra and say maybe quasi normal--try two "short ones"
Of course the cars have knock sensors, but it takes some actual knock for them to back off in the first place. Underneath this though, in the last month, your ave. engine operating temp may be up 10 degrees just with the weather change, and if you are in an area where oxegenates are used like most Metro areas now (as in alcohol these days), those can also raise octane (though lower economy due to their lesser energy content). They are used in the winter up to half the year now in some places as I recall, not the summer half, so just about now the fuel suppliers would have changed their gas blend for it. Thus, I'm more apt to run mid or even regular in cold winter months and cut over to Premium by now for the warmer season.
All this aside, dump two "short ones" in your tank and likely call it good. In this case TWO x 12 ounce Techrons that is, not the short beers. Seriously, cleaning up the valves some will get some localized hot spots out of the mixture flow around the valves and piston crowns and thus clean up some knocking that is also more pronounced as ambient air temps rise. It's about one ounce per gallon of gas, and given the 100L tanks these have, two times the 12 ounce size is a bit closer to the optimum recipe than by shorting it with the one x 20 ounce tall boy alternative.
All this aside, dump two "short ones" in your tank and likely call it good. In this case TWO x 12 ounce Techrons that is, not the short beers. Seriously, cleaning up the valves some will get some localized hot spots out of the mixture flow around the valves and piston crowns and thus clean up some knocking that is also more pronounced as ambient air temps rise. It's about one ounce per gallon of gas, and given the 100L tanks these have, two times the 12 ounce size is a bit closer to the optimum recipe than by shorting it with the one x 20 ounce tall boy alternative.
Last edited by MP4.2+6.0; Apr 16, 2010 at 06:32 PM.
AudiWorld Member
Joined: Oct 2009
Posts: 161
Likes: 0
From: Willow Springs, IL
Of course the cars have knock sensors, but it takes some actual knock for them to back off in the first place. Underneath this though, in the last month, your ave. engine operating temp may be up 10 degrees just with the weather change, and if you are in an area where oxegenates are used like most Metro areas now (as in alcohol these days), those can also raise octane (though lower economy due to their lesser energy content). They are used in the winter up to half the year now in some places as I recall, not the summer half, so just about now the fuel suppliers would have changed their gas blend for it. Thus, I'm more apt to run mid or even regular in cold winter months and cut over to Premium by now for the warmer season.
All this aside, dump two "short ones" in your tank and likely call it good. In this case TWO x 12 ounce Techrons that is, not the short beers. Seriously, cleaning up the valves some will get some localized hot spots out of the mixture flow around the valves and piston crowns and thus clean up some knocking that is also more pronounced as ambient air temps rise. It's about one ounce per gallon of gas, and given the 100L tanks these have, two times the 12 ounce size is a bit closer to the optimum recipe than by shorting it with the one x 20 ounce tall boy alternative.
All this aside, dump two "short ones" in your tank and likely call it good. In this case TWO x 12 ounce Techrons that is, not the short beers. Seriously, cleaning up the valves some will get some localized hot spots out of the mixture flow around the valves and piston crowns and thus clean up some knocking that is also more pronounced as ambient air temps rise. It's about one ounce per gallon of gas, and given the 100L tanks these have, two times the 12 ounce size is a bit closer to the optimum recipe than by shorting it with the one x 20 ounce tall boy alternative.
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