HLAs or Knock?
 

I've been noticing a "tick" lately during idle and while driving. It comes and goes and increases frequency when driving (sounding like a card stuck in a bike wheel).

Here's a video of it:
http://www.youtube.com/v/HpLDoKog2UM

I've had noisey HLAs before but they always go away almost immediately. This seems louder and sticks around for a spell before going. I first noticed it at the last AutoX I was at. I was in the grid and my car was ticking very loud. Distracted me for the next run, and then went away.

I run 89 octane and my timing is 10 degrees.

I honestly am not sure what knock sounds like exactly (or ping for that matter) so I ask you guys.

Edit: looks like the video isn't done processing yet. =( It may not be available when you click it.

Ok, it's up now... apologies. (and after looking at some of the other videos it seems much less large metal hitting large metal and more clicky... so I'm not so sure it's knock at all)

that's a typical miata sound. change your oil. maybe replace plugs and wires.


knock is pre-ignition. it's not acutally something hitting something.

Awesome, that's great news. Since I started futzing with my car I've been more and more sensitive to noises that I'm not sure about.

And thanks for the clarification. I knew knock was pre-ignition, but for some reason thought it cause something to hit. Doh.

So just so I have a reference, is this knock? Or is "rod knock" a different thing entirely?

http://www.youtube.com/watch?v=hMWwk47s0ak

your car is the HLAs, that second vid i'm not sure maybe valves.

Sorry, I mean to say knock is detonation. Pre-ignition may lead to knock and engine knock may lead to pre-ignition.

knock = detonation. detonation is tiny explosions of unburned air/fuel when you dont want it. it's called knock cause you can hear it.

I highly doubt you'll knock at idle. What you are hearing is HLA noise, so of it sounds like injectors and electrical.

the second video posted is a fubarded engine with bent rods.

that's a bad day. Cack that one open.

The first vid is HLA noise. Throw some ATF in the oil and put 30 miles or so on the car. ATF makes valve train squeaky clean. I had bad lifter noise and sludge when I bought my car. I put a whole quart of ATF in, drove it 40 miles home. Drained it, ran shit oil for 2000 miles, then switched to synthetic and everything under my valve cover looks good now.