I got spark knock

[Sparky]

I got pinging in the 5.3 on my 07 Silverado.

Actually, have had it for a long time, just having never heard spark knock before I thought it was just some sheet metal lightly rattling someplace. Realized after a discussion with someone and then listening to a video of spark knock that geez, that's probably actually what I'm hearing. Fired up Torque, put a KR chart up, and while driving when I start hearing that little tinging the line in the chart starts bouncing and smooths to zero when it stops.

Seems to mostly do it under moderate engine load, say cruising the state route going up a hill. It also seems to run normally otherwise, not really noticing power drops even when the KR starts kicking in. Perhaps I'd only notice that if it was to drastically pull timing? Mostly seems to pull only a few degrees.

I just installed a catch can not that long ago, and I have seafoam in this tank of gas (not quite 1/2 way through it), and I was thinking of also getting seafoam spray to try cleaning the intake side of things, going to clean the MAF, and I'm also going to check the spark plugs. The truck had 128k when I bought it a year ago (now has 140,600), and the dealer had done a number of maintenance items to it before putting it on the lot, but I do not recall if spark plugs and/or wires were done or not.

Anything else worth checking that I may be missing?

It is worth noting I do have a canned 87 tune from a Diablosport inTune on it (primarily to disable AFM), but I've heard this sound long before I even got that.

 

[Wooluf1952]

Is it possible the tune was for 92 octane? Have you tried premium gas?

 

[Sparky]

Maybe, but I am 90% sure I've heard this noise before I ever tuned it, and 98% sure that I don't even have a 91 octane tune loaded as available on the tuner.

 

[littleblazer]

A de-carbon treatment probably wouldn't be a bad place to start. Iirc pinging is pre ignition so it's detonating early. Could be the wrong plugs or something like that. Start simple.

 

[mrrsm]

Definitely sounds like the "Glow Plug" phenomena of having Red Hot Carbon pieces setting off the Fuel Air Mixture prior to reaching a few degrees B4 TDC (which will actually explode rather than burn at the proper quench) and the follow-on shock-wave is the audible "ping" you keep hearing. The REAL problem with allowing this to carry on too long... is that when the Pre-Ignition occurs while the crankshaft journal is still on the upswing...The Upward Momentum of the Crank...combined with the unexpected explosive Downward Force of the Pre-Ignition...will cause the Babbitt Bearings to be pounded on and eventually...CRUSHED FLAT.. and so if enough of these "pinging" or Deisel-ing like events keep happening... the problem will need to be dealt with ASAP by De-Carbonizing all of the Combustion Chambers as suggested by @littleblazer ... or else you run the risk of destroying the bearings of the involved Connecting Rod(s) enough to cause ROD KNOCK and ruin the engine entirely. Now even though this video is meant for Piston Engines in Aircraft... The Principles INVOLVED for All Automotive Gasoline Burning Four Cycle Combustion Engines are IDENTICAL:

And here is a Classroom Textbook Breakdwon:

And this version from Eric the Car Guy:

And so...as it concerns using the Various Grades of Gasoline Octane... many people labour under the illusion that Higher Octane Fuels somehow have ingredients that allow them to explode and burn with MORE FORCE AND POWER. But nothing could be further from the truth. Higher Octane fuels are chemically formulated to burn more uniformly and with LESS EXPLOSIVE FORCE at much Higher Compression levels...otherwise...the High Compression Engines USING "CHEAP 87 OCTANE GAS" would all suffer from the effects of pre-ignition events all the time. In the case of Diesel Engines...the compression ratios are so enormously high at around 18 to 1 ...that the Lower Volatility Grade Diesel Fuel to Air Mixture spontaneously ignites because ALL GASES HEAT UP... WHEN COMPRESSED...hence generally...there is no need for most Diesel Engines to employ any Spark Plugs or Wired Ignition Systems.

 

[Sparky]

I ran a tank of seafoam - can't say it made any difference but it is more fuel system cleaning than anything. I have the seafoam spray to use in the intake, just have to have time to do it plus have someone maintain engine RPM (since it is DBW I can't do it from under the hood myself).

When the engine is cold it doesn't do it, but once warmed up is when it starts, which makes sense.

 

[mrrsm]

@Sparky ....

FWIW...

In leiu of using Seafoam.... Try using something more SPECIFIC TO CYLINDER COMBUSTION CHAMBER CLEANING like BERRYMAN'S PROFESSIONAL TOP CYLINDER CLEANING KIT... as it will be much more successful in solving your problem than any standard application of Seafoam ever will. The introduction of this Liquid Upper Cylinder Cleaner into the engine intake is procedurally identical...with the exception that it Does NOT get put into either the Engine Oil or Gas Tank:

 

[littleblazer]

I ran a tank of seafoam - can't say it made any difference but it is more fuel system cleaning than anything. I have the seafoam spray to use in the intake, just have to have time to do it plus have someone maintain engine RPM (since it is DBW I can't do it from under the hood myself).

When the engine is cold it doesn't do it, but once warmed up is when it starts, which makes sense.

If you go slow enough you can idle it. Food for thought.

 

[gmcman]

I would run a tank of BG 44K through it, it's pretty much the strongest cleaner that you can run through your tank.

After that, it should have most of the carbon softened up or removed and then I would use the top engine cleaner.