Help. Can't get rid of knock :(

[MadMaxHSV]

Don't know if i'm chasing my tale with false knock or what but i've got persistent knock despite logs showing rich mixture and bugger all timing.

I've tried pulling timing in the area, with no apparent effect, to the point I feel timing is quite retarded.
Non of it is sawtoothed but then i've been lifting as soon as the dash flashes knock.

Any advice as to how to move forward? Log attached (example at 18:23:06:686) 10545. Excuse the fuelling, thats still work in progress (but on the rich side)

Many thanks

[Boost]

maybe with the earphones you can listen in for real knock. on our engines there is a LOT of false knock. doesn't somebody have a nice filter that can be set up?

[Boost]

oh and one more thing I think too much fuel can cause "knock" also! in a way

[MadMaxHSV]

Been finding lots of similar threads around this.
Looks like determining real knock can be problematic with "knock" even present on the stock tune.

Few things to try tomorrow.

[joecar]

Yes, I've read about rich knock.


The stock tune does knock at times.

[MadMaxHSV]

Hmmm not heard of rich knock before. *goes and reads up*

I guess its caused by turning the engine into a diesel motor? Too much fuel compressing combusts?

Could be the cause of some of it. Will get fuelling addressed to eliminate this cause first, then try to resolve the remainder.

[odd boy]

did u check spark plugs, if they are black they make misfire.

[MadMaxHSV]

I think I have a mixture of knock types which threw me. This rich knock business was new to me.
I've worked more on the fuelling so not running as rich which has helped in some areas, and pulled more timing in other areas which as reduced it also.

Think I was also expecting too much in terms of timing advance for my setup. Found some more reference timing maps for maggie blowers which run a load less timing then i'm trying in the mid load area.

More testing today.

[MadMaxHSV]

Fuelling is pretty good now and timing doesn't seem ridiculous, but i'm still hitting knock under load. Does this knock look real? 10596 (again its not sustained, but i'm lifting a the first sign)

Tomorrow i'm going to go drastic and pull a stack of timing all over and see if it goes away. Otherwise I guess its mechanical from something...

[joecar]

It looks like something else other than knock to me.

[MadMaxHSV]

Tried a few more things to eliminate some possibilities.

- Changed plugs from platinums to coppers (heat range 6) to ensure plugs weren't causing the knock

Log here shows a run after the plug change. 10616 Same situation as before

- Pulled 3 degrees across the timing map (map already quite retarded)

Log here shoes a run after the timing change. 10617 Same situation

Unless something else in the cylinder is getting a hot spot. Thinking false knock.

Joe, out of interest, what makes you say it doesn't look like real knock.

If it is false I guess its likely a resonance thing that something is rattling around those load areas.

[joecar]

Reduce your pid channel count to 24 or less (reads frames from PCM at maximum sample rate, 10 Samples/second), this will show a clearer picture of KR.

I see very small KR (1° or less) very infrequently, looking like a single short pulse, and not corresponding to any load/airmass increase, so it leads me to conclude it isn't knock related.

[odd boy]

r u sure there is no vibration around the knock sensor? or any object hits the block??

[MadMaxHSV]

Jeez start looking and you find lots of hidden issues.

- Knock sensor loom had fallen onto the headers (now strapped back)
- Slight exhaust leak from one header gasket (bolts re-torqued)
- Track-rod ends sound FUBAR'd. Rack knocks when jogging the steering
- One header branch is sitting hard against a nodule of the block (won't budge so can't see it knocking though.)

Returned the timing higher slightly again and reran after strapping the loom and torquing the headers. Still there.

Does come on under acceleration but if constant with the throttle (keeping it down) pings once then stops. Bleeps a few times if off/on slightly. log attached 10628 (still look like false knock?) I'd already upped the recovery rate hence it ramps back quite fast.
Gotta be something rattling.

Will attempt to address the issues above and try again.

[madmax4499]

what did you end up finding? is that little KR even worth worrying about? when or how much KR is bad?

[J.Abbott]

If this is a LS engine, you are getting oil ingestion. Check your PCV and then install a catch can. Good Luck

[MadMaxHSV]

Latest update is its still there, but minor. WOT on the dyno there was no KR at all.
Largely ignoring it for now. I've tried bringing PE on earlier which seems to have made improvement but could be placebo effect as the KR was showing up in the logs under PE before.

I've already got an altered PCV system with catch can so the heavy oil ingestion of the original setup is gone, this isn't the issue. Cleared up a lot after I rebuilt the motor anyway with better rings.

[J.Abbott]

Where are getting the KR at, 4K

[MadMaxHSV]

Usually get it at half throttle between 3-4k

[J.Abbott]

So it is happening at pretty much peak torque. What is the timing right there and what is done to the engine. Also what g/sec on the cylinder are you at when it is giving the KR.

[MadMaxHSV]

Ok i've managed to reduce this considerably. Changed my PE setting to come in based on MAP of 80kpa, with low throttle across the board.

The knock must have been occuring on the boundary, around half throttle depending on the loading.