light engine pinging

[pimpbot]

Hi all,

I have a 2007 Avant 2.0t MT6 I picked up a few months ago form a reputable dealer. The car had 78k miles on it when I bought it, now 82k. The car had the head replaced on it while the dealer had it (and he had paperwork from an Audi dealership to back it up), I assume because of the HPFP cam issue, but it didn't say exactly why the diagnosis was for the head replacement. I hope it wasn't for detonation damage.

So, I noticed when pushing the car up a hill, or in stop and go traffic (seemingly almost no load, but higher coolant temps), it pings. Not super hard, but it's there. I'm concerned that whatever condition that took out the first cylinder head might be still going on.

I've checked that there is sufficient coolant in the engine, sufficient oil (had it changed once already), and by the OBD2 readings, the coolant doesn't get hotter than 94C.

Seems reasonable.

I guess I haven't double checked the plug gap... or even what plugs they used. I assume they are new since it's a new head. That sounds like my next step. I used good Chevron super gas, but that doesn't seem to make a difference in this case when using cheap super gas.

Is there anything else I can try, if the plugs fall in spec?

[JDillon15]

Assuming I read your gas comment correctly, you ONLY want to use high premium fuel in these cars. I wouldn't go lower than 91 oct.

[Scotty@Advanced]

If your getting detonation, the computer should record that as a fault. If the timing belt went it could have caused dents in the pistons which will produce hot spots and can cause detonation. Had the same issue with an S6 that had broken a belt.

[pimpbot]

If your getting detonation, the computer should record that as a fault. If the timing belt went it could have caused dents in the pistons which will produce hot spots and can cause detonation. Had the same issue with an S6 that had broken a belt.


Oh, you may be on to something. I guess a flexible mini cam scope would show dents in the pistons in that case.

Yes, I always use Super gas. 91 octane is the norm here in NorCal. I occasionally see 92, but its rare. I was just saying that I running cheap no-brand Super gas or Chevron Super didn't make a difference in the pinging.

I'll try new spark plugs first, and make sure they are properly gapped. Maybe I should pull my existing plugs.

If everything checks out, would using a colder or hotter sparkplug make a difference? I heard Copper plugs don't cause preignition as easily as Iridium, but they wear out in 10k miles.

BTW, I'm not getting any codes. This is more of 'something that doesn't sound good to my ears' kinda thing.

[pimpbot]

Oh, you may be on to something. I guess a flexible mini cam scope would show dents in the pistons in that case.

Yes, I always use Super gas. 91 octane is the norm here in NorCal. I occasionally see 92, but its rare. I was just saying that I running cheap no-brand Super gas or Chevron Super didn't make a difference in the pinging.

I'll try new spark plugs first, and make sure they are properly gapped. Maybe I should pull my existing plugs.

If everything checks out, would using a colder or hotter sparkplug make a difference? I heard Copper plugs don't cause preignition as easily as Iridium, but they wear out in 10k miles.

BTW, I'm not getting any codes. This is more of 'something that doesn't sound good to my ears' kinda thing.


Hey all,

So I checked out my spark plugs. They looked good, but they were gapped to 0.028 instead of 0.032. I'm not sure how much difference it would make, so I pulled them all and regapped them to 0.32. It seems to have fixed the issue, but I only have one drive on them.... up the steep hill to my house in Oakland. I was able to pull 45 mph in 4th and 5th gear most of the way up the hill with the turbo at a constant 1.0 bar, 2000 ish RPM, and it didn't ping at all. It seems to be running a bit smoother, but more growly when cold. Maybe it's my imagination.

I'll give it a few more days. The air was kinda cool today at 64F. Maybe it will ping on a warmer day.

Also, it seems I didn't get as good gas mileage on my commute home. Could that be true... or, again, probably just my imagination.