2015 ZL1 knock? Conclusion @ 4/27/15

[angryBits]

Found it! But I'm not showing any data for the KR Cyl 1-8, do they need to be active while I'm recording?

EDIT: Nevermind... I seem to have figured out how to add the graphs and charts for these values but no data is showing up. Do I have to turn these on somewhere?

EDIT EDIT: Ahhh! The Table! I have to add the PIDs to the table for the tool to record them Ok next post should have some juicy data.

[angryBits]

*Conclusion*

Juicy Data as promised

Please note, this drive was in 91 octane, where the previous attachment in an earlier post was in 92-93 octane (likely a little lower than 93).

In the attached .zip there are 3 files all driven under the same conditions
91 octane, 45 degrees outside and sprinkling.

5Pow.hpl - My car went POW. Very loud audible knock, registered 9+ KR. It was so loud it scared me. This file was scanned while not logging KR or KL per cylinder.

6data.hpl - Easy drive while scanning KR and KL on all cylinders, some small to medium knocks.

7data.hpl - Driving a bit harder while scanning KR and KL on all cylinders, some medium to large knocks - even caught a 10+ KR!

knockpercyl.cfg is the config file I used to view the KR and KL per cylindner.

I welcome input from someone with more experience but I'm unable to find a pattern in the cylinders. They all seem to peak randomly which suggests to me there isn't any particular issue with any particular cylinder. So I'm finally convinced that this car just knocks REALLY bad on 91 octane... REALLY BAD. You can tell a difference between the 92-93 from the earlier 3knock.zip attachment above where it was not audible and maxed at about 5deg, and the 91 octane in these attachments easily hit 5deg and several times hit 9-10deg and was very audible.

My Conclusion: (I can totally be wrong so dont hate)
My car isn't any different than anyone elses. These cars just REALLY NEED 93. Even on 93, you're still probably knocking some of the time @ WOT, its just in the 2-5deg range and not audible (probably not the end of the world). Having seen (and heard!) the knock on 91, I don't recommend anyone drive this car on 91 without an aftermarket tune or mixed with some Race Gas or Torco. I plan to try cooler spark plugs and if that doesn't help enough, then I'll get an aftermarket tune.

Finally:
My apologies for all the fuss -- though in my defense I don't really consider buying a new car and getting audible knock "nothing to fuss about".

Thanks everyone for all the help!

[CAM....ZL1]

angrybits, I have read somewhere that up to 6* of knock from the factory is possible or even common. I think maybe your factory calibration may be a little off ( on the aggressive side ). I am tuned for 93 and 98 and only use the 98 for the strip.I see a high of .18-.23 degrees of knock but only for a split second and it goes away. I could have it tuned completely out but choose to
keep the more aggressive tune. Seems like you have too much timing or not enough fueling.

[Nor Cal ZL1]

Like I said beore take it in and have everything checked out. Could be as simple as a lazy fuel pump. I have no problems on cali 91. I do have a CAI from cold air inductions which is reported to fatten up the mixture a bit so maybe that is helping. I know you say Abel is far but you need to go.

[Vroom]

You really should just take it in. You shouldn't be hearing and knock noise. 85k miles of 91 and even when I get some knock, I don't hear anything.With the amount of time and money you've wasted trying to diagnosis this yourself, Abel would have fixed it by now.

[Nor Cal ZL1]

Originally Posted by Vroom

You really should just take it in. You shouldn't be hearing and knock noise. 85k miles of 91 and even when I get some knock, I don't hear anything.With the amount of time and money you've wasted trying to diagnosis this yourself, Abel would have fixed it by now.

I know. There are a few reasons the knock can be there ranging from marginal fuel pressure/regulation, marginal sensor/calibration, bent timing pick up sensors, wrong factory tune, wrong injectors. None of which I suspect has been checked.

[Six.Two SC]

According to Tampa Tuning, 4-6 degrees of KR is normal stock, even with 93 octane. I run 91 octane and see up to 6 degrees at WOT all the time. I don't hear anything strange, though. I'll have some boostane in a couple days.


Sent from my iPhone using Tapatalk

[angryBits]

Originally Posted by CAM....ZL1

angrybits, I have read somewhere that up to 6* of knock from the factory is possible or even common. I think maybe your factory calibration may be a little off ( on the aggressive side ). I am tuned for 93 and 98 and only use the 98 for the strip.I see a high of .18-.23 degrees of knock but only for a split second and it goes away. I could have it tuned completely out but choose to
keep the more aggressive tune. Seems like you have too much timing or not enough fueling.

Yes, this sounds right to me. My data logging suggests my injectors are only at 65% capacity at WOT when I knock, so I think fueling is okay unless I've got a bad injector.

Originally Posted by Nor Cal ZL1

Like I said beore take it in and have everything checked out. Could be as simple as a lazy fuel pump. I have no problems on cali 91. I do have a CAI from cold air inductions which is reported to fatten up the mixture a bit so maybe that is helping. I know you say Abel is far but you need to go.

No, CAI will only make things worse as it would lean out the AFR. You're most likely knocking but not hearing it.

Originally Posted by Vroom

You really should just take it in. You shouldn't be hearing and knock noise. 85k miles of 91 and even when I get some knock, I don't hear anything.With the amount of time and money you've wasted trying to diagnosis this yourself, Abel would have fixed it by now.

I haven't had the opportunity to take it in yet. Life gets in the way sometimes. My car can't always be my #1

Originally Posted by Nor Cal ZL1

I know. There are a few reasons the knock can be there ranging from marginal fuel pressure/regulation, marginal sensor/calibration, bent timing pick up sensors, wrong factory tune, wrong injectors. None of which I suspect has been checked.

My data logging says fuel pressure and all that is good. A bent timing sensor is possible and has not been checked. Wrong factory tune or wrong injectors? I don't think that's it.

Originally Posted by Six.Two SC

According to Tampa Tuning, 4-6 degrees of KR is normal stock, even with 93 octane. I run 91 octane and see up to 6 degrees at WOT all the time. I don't hear anything strange, though. I'll have some boostane in a couple days.

Yep, this is what I think. I think this is normal. I know for a fact I have extremely good hearing -- I can't smell worth a darn but I've got ears like a dog. I think everyone with a stock tune knocks with this car even on 93. I think on 93 its just marginal and not harmful. I think on 91 it's moderate and some of the bigger ones could be harmful over a long period of time.



I'd really like to hear from someone that knows how to read a HP Tuner log better than I do and tell me what they think of my log. Guessing doesn't get us anywhere.

Thanks for your help.

[Six.Two SC]

I've had both the Roto-Fab and CAI and my LTFT's at WOT went from positive(stock) to negative. So, wouldn't that mean they fattened up the tune? IIRC, the LTFT's weren't as negative with the CAI, but I got more KR. I THINK, not positive about the KR.

[Nor Cal ZL1]

In testing various cold air intakes resulted in a fatter mixture, it has to do with the fuel trim. My car runs fat with the CAI.

Sensors can read wrong values, but not often.

I have been a mechanical/electrical troubleshooter for 30 years and learned many years ago..... never discount the unlikely. You need to systematicaly eliminate probable causes including things that are not likely to happen. Been there too many times.


https://docs.google.com/spreadsheets...=1&output=html

[Six.Two SC]

Originally Posted by Nor Cal ZL1

In testing various cold air intakes resulted in a fatter mixture, it has to do with the fuel trim. My car runs fat with the CAI.

Sensors can read wrong values, but not often.

I have been a mechanical/electrical troubleshooter for 30 years and learned many years ago..... never discount the unlikely. You need to systematicaly eliminate probable causes including things that are not likely to happen. Been there too many times.


https://docs.google.com/spreadsheets...=1&output=html

Wow, Rotofab didn't fare will in this test.

[Balasarius]

Originally Posted by Nor Cal ZL1

https://docs.google.com/spreadsheets...=1&output=html

This is awesome.

[ZO6 Bryan]

Originally Posted by Balasarius

This is awesome.

You all do realize that that document is old? That is not the "no tune" Roto fab that was designed for the ZL1. It was the original Roto fab that was designed for the SS.

[Six.Two SC]

Originally Posted by ZO6 Bryan

It was the original Roto fab that was designed for the SS.

That would make sense. I thought, WTF?!?!?