Z06 stock tune 8* KNOCK RETARD!

[CAMAROZ28AQUINO]

hey guys i have a 2006 corvette z06. Car has American Racing longtube headers with cats and corsa exhaust. I am getting up to 8 degrees of knock retard. does anyone know what the hell is going on? ive run 3 tanks of Shell 91 octane through it and no luck....im puzzled

[BBA]

They have KR with factory tune and 93 octane, what did you expect with 91 octane?
The only option is to do a KR logging and timing modification tuning process. That or run 100 octane racing gas, which will really let it run to it's full potential.

[CAMAROZ28AQUINO]

so your telling me that all z06s knock up to 8* from the factory? this is the first my tuner has seen this bad and hes tuned 100's of Z06s

[vortech]

Anthony email me your tune and I'll tell you what to adjust to calm that down.

[email protected]

[Sneakyws6]

Dang, IAT's are in the 130* when the run starts then bottom out at 63* or so. What where you doing, injecting NOS right into the intake tract?

Coolant temps are in the 195* range as well. Have the IAT tables, Knock Retard tables, Brst Knock tables been adjusted as of yet?

I bet some of that knock is false and is being pulled by the IAT and ECT tables to reduce knock.

[EC_Tune]

False KR is not uncommon either.

[CAMAROZ28AQUINO]

Dang, IAT's are in the 130* when the run starts then bottom out at 63* or so. What where you doing, injecting NOS right into the intake tract?

Coolant temps are in the 195* range as well. Have the IAT tables, Knock Retard tables, Brst Knock tables been adjusted as of yet?

I bet some of that knock is false and is being pulled by the IAT and ECT tables to reduce knock.

hey man i just drive the car around town and dont do any racing or anything.

[BBA]

so your telling me that all z06s knock up to 8* from the factory? this is the first my tuner has seen this bad and hes tuned 100's of Z06s

Yep, especially on 91 octane gas. You really need to tweak the timing tables. Set the knock retard decay table values as high as they will go, log some driving for KR, reduces only the cells that the KR occurs in by 1/2 the KR value detected, do this in both high and low octane tables and log/flash more until the max KR you see is around 2º or less. Then you can set the decay rate tables lower, about 2 to 3 times the factory table values will work, because you want to remove KR as soon as the event is over to keep from losing power.

Remember, the Z06's had KR on 93 octane and they were never designed to run on 91 octane gas at all, so your just aggravating the issue.

[CAMAROZ28AQUINO]

alright i will try this out but will there always be knock in this car no matter what? Could the sensors be bad? I had knock when the car was bone stock too

[Sneakyws6]

I am almost for sure GM did not design the Z06 to run on 93 only seeing as it is not readily available in almot half of the USA.

I can assure you those timing table were built around 91 octane for the high octane table the 87 for the low octane table.

If you want to make sure that the knock is not fuel caused then run the tank clean and dump in some 100/104 octane and then try your /logs pulls again. If the KR is still there than you have something else causing the KR.

[jimmyblue]

I despise Shell gasoline. Starting with the lies in their commercials
and ending with a tank full o' ping.

But first off, I would look at Misfire Current Cylinder 1-8 logging,
be sure you do not have an injector imbalance problem (one lean
delivery) that could bring in KR at advance that "should" usually
be OK. Just looking for any hints.

I would also get a fuel pressure gauge on there and look at the
pressure across the load range, since your KR gets worse as you
go up in RPM and MAP; maybe there is a general fuel shortfall.

The log doesn't have any wideband readings so no idea whether
fueling is sane or not.

I would cut the KR attack rate in half and double the decay rate
for starters, you have big steps up and forever coming down at
stock settings, which obscures the real action.

[LazMan]

In 2009, GM changed Spark -> Spark Retard -> Max Valid from 12 degrees in 2006 to 1.3 degrees in order to eliminate a lot of false knock that came with these engines, stock.

Try that.

See pics.

[Nithros]

In 2009, GM changed Spark -> Spark Retard -> Max Valid from 12 degrees in 2006 to 1.3 degrees in order to eliminate a lot of false knock that came with these engines, stock.

Try that.

See pics.

I just made this same change to my 2008 Z06 and saw no detrimental results so far. I had always heard they were way too sensitive in 2008 and the proof was that GM lowered the sensitivity in 2009.

However, that seems like a huge adjustment - I don't understand it though since it says "Maximum retard before it's considered false knock". I can see where that number could be 12 but not 1.3. I guess I don't understand what this setting means just by reading the HPT text. Can anyone shed some light on this? Is it 1.3 retard, degrees or what?

[Sneakyws6]

I Believe It Means It Has To Be More Than 1.3° Of Kr Before The Ecm Considers It Knock And Uses The Knock Retard Tables To Control The Kr.

[LazMan]

I believe its the other way around sneaky - any instantaneous read of over 1.3 is considered bupkis. False. Rattles, or whatever. My guess at the logic is "0 knock to 12 knock in one instant? False."

Some other cars use 2.0 instead as the threshold - use that if you dont feel ok with GM's stock number - BUT - GM is very conservative and Id trust their 1.3.

[Nithros]

Thanks for the info LazMan.