I'm new to this stuff, C6Z knocking, can someone look at these logs?

[Ebengtson82]

The car is a 2006 Z06 with the following mods:

236/245, .648/.650, 114 LSA cam
ported/milled .020" heads
ported MSD intake manifold
Halltech mf108
NW102
vette air scoop
1 7/8" catted ARH
corsa catback
ngk tr6ix plugs
mighty mouse PCV catch can
160* tstat
running 92 octane chevron gas

Had the car professionally tuned, but there was apparently a problem with the wideband calibration. (Flew tuner in and rented a local dyno) The car wasn't trapping what it should for the power level (552whp/516wtq) at 128mph, so I bought hptuners and the AEM UEGO and sent him logs. AFR was rich at 11.6, so he leaned it out and sent me a reflash.

Tried the new tune out in a grudge racing elimination tournament and I gained 4-5mph in the 1/8, but was trapping the same 128 mph. Running 10.7's consistently and letting the car cool down with the hood open between rounds. So as I started winning, rounds got shorter, and the car didn't have much time to cool. Somehow It got faster. Ran 10.558 @ 131, then finally lost in the finals with a 10.533 @ 131.75.

The logs are showing a decent amount of knock retard, but it's really not running THAT lean at ~12.4 AFR. Any idea why it got faster? What can I do to fix it? Tuner stopped responding so it looks like I'm on my own.

Attached are 4 log files. Wood 2 & 4 are 10.7@128, wood 5 & 6 are 10.5@131. Nothing changed from run to run besides a psi drop in tire pressure and less cool down time between runs.

wood2.hpl
wood4.hpl
wood5.hpl
wood6.hpl

Thanks in advance.
Erik

[5FDP]

Could you post the tune here aswell??

May be something that someone see's that is off in the tune.

[Ebengtson82]

Here it is:

erik 06 c6 z06 235-245, nw102, mf108 tune .bin

[GHuggins]

I would recommend pulling at least 1 degree from 4400 up... more timing doesn't always mean more power

[schpenxel]

Add knock learn factor to the list of channels you're logging also--I'd be curious to see what it's doing

And to Greg's point... that is something I wish everyone understood. Once you you get to the point where peak cylinder pressure is happening at the "best" point after TDC (say, around 15* after TDC or so), advancing it beyond that will actually reduce power at the wheels and make cylinder pressures go through the roof.. so more is not always better

I'd def pull a degree or two in the 4400+ range too

[Ebengtson82]

Thanks for the replies. I'll try to figure out how to change the timing and make the necessary adjustments.

[Ebengtson82]

Would I benefit from going to a TR7 or TR7IX plug?

[GHuggins]

If you don't all ready have a colder plug, go with the IX's - won't give you as much trouble cruising around...

[Ebengtson82]

So the TR7IX is a better choice than the TR6IX I'm currently running?

Also, anyone have an idea why the car was getting faster as it got hotter?

[GHuggins]

So the TR7IX is a better choice than the TR6IX I'm currently running?

Also, anyone have an idea why the car was getting faster as it got hotter?

This is what I meant by if your not all ready running colder plugs As for hotter - pulling timing, better fuel atomization, can't really say?

[Ebengtson82]

Just ordered some denso it22's. I'll put these in, and change the timing in the tune but not upload it unless I need it next time I'm at the track.

[twistedpixels]

I had a very similar cam but yours is on a 114 which is going to bleed more pressure than mine at 112 +4. I had the same issues on pump gas/torco and then even on e85/91 mix. It will get kr at part throttle and sometimes at peak torque but tends to be ok if i nail it from a lower rpm like say 3000. If i bring rpms up to 4000 in 3rd and roll into it it will ping but if i nail it fast it wont. Seems to be a PE delay even though mine is not delayed hardly at all. I went with a a little larger cam now to bleed more pressure but still have the same issues even with denso it 24's and straight e80. It was fine on the dyno but on the street it gets the same kind of random kr at part throttle in the higher rpms rolling into it and sometimes at peak torque if i nail it at a lower rpm.

I have tried setting the tps pe enable at 5% and zeroing out all the values for pe enable and set the kpa enable at 40. I have also tried advancing and retarding injection timing with no luck. My afr was dialed in by my tuner with his AFR meter and he was really happy with how consistent it looked when i put the new injectors in. IT is right around the 12.6 area across the board.

I even went and globally removed 4 degrees and it still happens. I can hear it so it is not false knock. Mine is an 07 so I am wondering if this is a common issue with the older Z's since i know in the later models they made changes to the ecu and some things are a little different for injector tables for instance.

One thing I did recently find and am fixing this weekend is an exhaust leak at the header flange on driver side. But this issue with KR has been going on for over 2 years and been chasing my tail. I have hanged injectors, plugs, wires, and even a bigger cam like I said to bleed more pressure. I even tried adding fuel to it. Nothing has worked. My afr meter may not be very good since i see KR and an afr of below 12 sometimes. This may be because of my exhaust leak though since it and the afr sensor are on the same side. I hope fixing the leak fixes the issue but honestly I doubt it. Almost seems like something is corrupted in my tune file maybe since it was previously tuned by a different guy when the parts when on. The issue has followed since my current tuner built of the other guys tune I think.

I always thought a vac leak may be the issue but i put on an MSD intake and made sure it was sealed and torqued properly. Also I have a GZ vac pump so even if I did have a leak it is likely going to mask it so I had to remove the belt to make sure after the install.

ANyway I hope you get it figured out and sorted.

I hope you get it figured out since the solution may work for mine as well.