A single loudish knock?

[idk706]

This rainy morning I take the car out to get coffee and everything is running smooth. It starts raining hard and I start to get a rough idle at stops (I'm 99% sure this is because of the water getting onto the rear coils) and I'm pretty used to it at that point, although I did just put new plugs with dielectric grease so idunnolol. I think I need to replace my coil packs because they were pretty dirty so i cleaned them up before putting them back on. Saw someone had fashioned a gasket to make sure water doesn't go past the rear garnish onto those rear coils so I'll do that soon
Anyways to my main concern, I drive maybe a total of 15 miles total to and from the coffee shop and I live up a not so super steep hill, as I start to make my way up the hill and I give it gas after like 2-3k rpm I heard a singular loudish knock, of course don't know wtf that was so so I stop for a few seconds and I try to reproduce the sound and it does it again after revving it back up a little to go past 30 mph and it does it one more time but not again after that even when trying to reproduce it again.
I get to my house, park it and just sit in park idling try to listen for anything suspicious, the rough idle is gone now presumably because it had stopped raining for a bit and it was dry. I don't hear any noise consistent with what would be considered engine knocking, so I really don't think (and hope) that isn't what it is.
Maybe my CV joint? Not sure. It sounded like it was coming from the engine bay but I don't know what else it could be.

 

[Old Guy]

The tripod joints on the drive shafts will typically not give a single knock. Once they start a knock'n it is going to be pretty continuous unless the tripod somehow was binding as it rotated.

If you have ever heard it, detonation is usually pretty distinct, like two rocks been knocked together. The knock sensors do not prevent detonation. They sense detonation and then pull timing (and other stuff) to prevent continuous detonation so it might have been the initiation of detonation that you heard before the knock control pulled the spark advance. Most algorithms will restore the timing to normal after a number of engine cycles and then the whole process can start over again. The pre OBDII ECUs have DTCs for knock sensor failure; but, no DTC if the engine has detonation. Same with the OBDII cars so you cannot go into the ECU memory to see if there is a stored code that would confirm that detonation occurred. Out of caution, I would pull the plugs and examine them for damage. A severe detonation event can fracture the center porcelain of the electrode. That said, cool wet weather actually suppresses detonation.

Without hearing the noise I don't have much in the way of suggestions as to a possible cause. Is it possible that you have a failed / failing ball joint or other suspension component? A lower ball joint can be pretty much failed; but still support the weight of the car; but will make noise as loading (drive torque) changes.

 

[idk706]

The tripod joints on the drive shafts will typically not give a single knock. Once they start a knock'n it is going to be pretty continuous unless the tripod somehow was binding as it rotated.

If you have ever heard it, detonation is usually pretty distinct, like two rocks been knocked together. The knock sensors do not prevent detonation. They sense detonation and then pull timing (and other stuff) to prevent continuous detonation so it might have been the initiation of detonation that you heard before the knock control pulled the spark advance. Most algorithms will restore the timing to normal after a number of engine cycles and then the whole process can start over again. The pre OBDII ECUs have DTCs for knock sensor failure; but, no DTC if the engine has detonation. Same with the OBDII cars so you cannot go into the ECU memory to see if there is a stored code that would confirm that detonation occurred. Out of caution, I would pull the plugs and examine them for damage. A severe detonation event can fracture the center porcelain of the electrode. That said, cool wet weather actually suppresses detonation.

Without hearing the noise I don't have much in the way of suggestions as to a possible cause. Is it possible that you have a failed / failing ball joint or other suspension component? A lower ball joint can be pretty much failed; but still support the weight of the car; but will make noise as loading (drive torque) changes.

Hey old guy. That sucks. I had just changed the spark plugs so i hope that isn't the case.
I haven't actually personally looked at the ball joints but when I had it initially inspected they seemed fine. But that was around 2k miles or so ago but still. I'll look at it more in depth thank you.