I frequently hear a short run of knock at moderate loads (e.g. ~50% throttle in 6th at ~60mph). I am using passive headphones wired to the knock sensor via an amp. Knock strength as logged by the ROM editor does not increase when I hear this "soft" knock. I was a little concerned to hear as much knock as I was hearing, so I first verified that it was really knock that I was hearing by inducing knock at lower loads (e.g. ~30% throttle in 3rd at ~30mph) by advancing timing across the board and going for a short, slow drive. The sound that I hear sounds like a soft crackle/clipping. Unlike before, when I induce knock the logged knock strength increases with the knock that I hear from the phones. The following sources seem to suggest that some knock is acceptable and "soft" knock might even be preferable.

http://www.contactmagazine.com/Issue...ineBasics.html
http://www.freepatentsonline.com/4337642.html

Any thoughts before I try to tune this knock out?

 

I had a similar knock headphone setup and was able to get rid of the audible ping except for high boost where it always pings a little (a little on headphones but not noticeable outside the car). I don't think it's normal to hear it in part throttle, unless you're hearing something else -- VQ's are very noisy. Any way you could post a MP3 sample?

 

Unfortunately, neither my phone nor my laptop want to record properly with a standard TRS phone jack. Gonna try a different app on my laptop to see if I can get a recording.

 

Looks like I'll have to make a TRRS adapter to get it to work since both my laptop and phone use the same jack for mic and speakers. I'm fairly sure what I am hearing is knock but couldn't find any samples to compare to. That's why I induced some knock. The only difference I can remember between the induced knock and the part throttle knock was that the induced knock was a bit louder and more frequent. Qualitatively, they sounded they same.

 

Phantom knock possibly.

My friend's 2j had some wickedly strange phantom knock outside of boost at very odd rpm, with low load. Did a leakage test and found one cylinder was leaking 50%. Haven't had time to catch up with him in a while but we assume a ring got facked sideways.

 

As per resmarted's comment, I'd send an oil sample to blackstone to rule out any serious issues before you spend a bunch of time tuning it.

 

Not a bad idea. I may just do that. Was also going to pull a plug or 2 to see how they look. It's odd though as it occurs in the vacuum portion of my map where I am either running stock timing or slightly retarded timing. I had put a few 1000 miles on the car since the turbo was installed. A built short block was eventually planned but I was hoping to put it off till next year. Car actually drives great otherwise. Pulls hard in vacuum and boost--no smoke, no hesitation. Even the death at idle miraculously disappeared on its own. But still have not really pushed it much because I was waiting to have the knock phones setup before I did. Now I'm back to just keeping it in vacuum.

 

Also check A/F and make sure it's not too lean, that could also cause constant knock. Should be 12's between -3 and 0psi and 13's anything over 25% throttle. If it's wandering into or above 14's while you're accelerating that would be a problem. Do your plugs have white tips?

 

Haven't had access to the car yet to pull the plugs but I did lean out the vacuum portion of my map. That could be contributing. Attached is a fuel map made from my datalog. It maps boost, target afr, actual afr and knock on the uprev fuel fuel map.

 

Pretty lean in the lower load areas (14-15) and even low boost... that's probably it. Bring anything over 25%-50% throttle and especially near or greater than 0psi to at most 13's. Work up from there.

 

Aww...crap.

I enrichened the lower load cells and redid the timing table and I've virtually eliminated knock via the phones. Also saw knock strength fall from the 1000's to near 0. I had driven nearly 3k miles on that tune. Whatever damage was done is done. I pulled a plug and it didn't look bad. Here it is.



Here's my old timing data:



Here's the new timing data:



Lessons learned:
1. if you are going to tune an FI car for the first time install a knock listening device asap.
2. on at least a 2004.5 ECU knock strength numbers in the 1000's should cause pause.

 

Probably fine. My Z's plug tips were solid white and eroded from running lean with a failed knock sensor harness for years before I got it. Luckily it was overly rich in boost (no hard knock) and everything ended up fine after I replaced the knock sensor harness and retuned it. Your plugs look virgin compared to the ones I pulled. Do a compression test to be sure!

 

Abnormal compression test itself wouldn't change what I do with the car in the near term. Just need it to be my daily driver till december when I pick up a tow vehicle which can also serve as my backup. Plan to follow oil analysis for a few changes. Should clear after my next change. Will maybe combine a compression test with some other mod like polishing the plenum or something at that time if indicated by oil consumption, etc..