Knock ?!?
Thread Starter
Intermediate
Joined: May 2009
Posts: 26
Likes: 0
From: Iowa
It's a 99 c5, manual, axle back exhaust, underdrive pulley, vararam, 75 shot
There is no noise at all. Config and Log in links.
Thanks for the help!
http://www.mediafire.com/?lodny52o1xi
http://www.mediafire.com/?5n0zw2mgezt
There is no noise at all. Config and Log in links.
Thanks for the help!
http://www.mediafire.com/?lodny52o1xi
http://www.mediafire.com/?5n0zw2mgezt
Racer
Joined: Apr 2009
Posts: 282
Likes: 0
From: Studio City CA
Post up a file for your tune.
Looking through that log it seems like you may be a bit lean, but is there any reason you are going WOT for short bursts below or a little above 2000rpm? Is this the only time the KR is kicking in?
In the Knock Retard histogram you can hit the + button to see the maximum knock retard in each cell and then copy it and paste special - subtract it from your spark advance table or try increasing your PE values at those rpms.
Also, do you have the nitrous set-up on a window switch or is it only on a WOT switch?
The idle problem may be in the tune or due to a mechanical issue. Make sure you have no vacuum leaks or any unmetered air coming in after the MAF. If everything is sound mechanically then you may need to tweak a few idle airflow tables in the tune.
Looking through that log it seems like you may be a bit lean, but is there any reason you are going WOT for short bursts below or a little above 2000rpm? Is this the only time the KR is kicking in?
In the Knock Retard histogram you can hit the + button to see the maximum knock retard in each cell and then copy it and paste special - subtract it from your spark advance table or try increasing your PE values at those rpms.
Also, do you have the nitrous set-up on a window switch or is it only on a WOT switch?
The idle problem may be in the tune or due to a mechanical issue. Make sure you have no vacuum leaks or any unmetered air coming in after the MAF. If everything is sound mechanically then you may need to tweak a few idle airflow tables in the tune.
Last edited by frcslave; Apr 5, 2010 at 08:02 AM.
Thread Starter
Intermediate
Joined: May 2009
Posts: 26
Likes: 0
From: Iowa
Car has the stock tune.
I am only seeing KR on WOT N/A runs in 3-4 gears. I lost the hard drive in the computer that those logs were on and was just trying to get KR to kick in logging last night (wet and rainy). I had just noticed from the one screenshot I still had from the old computer that when I was pulling a hill at cruise speeds it was also kicking in.
Nitrous is HSW microedge and interface. Windowed, A/F shutdowns 10-13, TPS.
I'll spray test for air leaks. Pretty good chance my nitrous plate isn't perfectly sealed.
Thanks for the help!
I am only seeing KR on WOT N/A runs in 3-4 gears. I lost the hard drive in the computer that those logs were on and was just trying to get KR to kick in logging last night (wet and rainy). I had just noticed from the one screenshot I still had from the old computer that when I was pulling a hill at cruise speeds it was also kicking in.
Nitrous is HSW microedge and interface. Windowed, A/F shutdowns 10-13, TPS.
I'll spray test for air leaks. Pretty good chance my nitrous plate isn't perfectly sealed.
Thanks for the help!
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
97-99's are prone for false knock issues---In 00 GM changed the sensors to fix this-- false knock can occur with engine mods--especially exhaust changes as the sensors are picking up new noises
You may be a bit lean as mentioned at WOT---I would start there especially with NOS you don't want that--Try addding some fuel in PE and see if it goes away- If not you can desensitize the knock sensors slightly at WOT only-- In the SPRK table go to "knock software" and go to the "cylider mode " "B" try addding .10 in the last 2-3 columns
(WOT) only
As far as the surge at idle you basically have a stock type eng--there should be no reason for surging so it sounds like you have a vacuum leak as mentioned or un-metered air coming in--If you can't find anything more than likely its a result of the varraram intake--You may have to adjust the ""desired airflow" table to compensate by adding a % to both tables start with 10%--But 1st make sure your LTFT fuel trims are in line ---"0" or slightly negativein the idle ranges
You may be a bit lean as mentioned at WOT---I would start there especially with NOS you don't want that--Try addding some fuel in PE and see if it goes away- If not you can desensitize the knock sensors slightly at WOT only-- In the SPRK table go to "knock software" and go to the "cylider mode " "B" try addding .10 in the last 2-3 columns
(WOT) only
As far as the surge at idle you basically have a stock type eng--there should be no reason for surging so it sounds like you have a vacuum leak as mentioned or un-metered air coming in--If you can't find anything more than likely its a result of the varraram intake--You may have to adjust the ""desired airflow" table to compensate by adding a % to both tables start with 10%--But 1st make sure your LTFT fuel trims are in line ---"0" or slightly negativein the idle ranges
Former Vendor
Joined: Oct 2005
Posts: 134
Likes: 0
From: Richmond va
The car is not in PE in the screen shot; it's clearly in CL. If you look at the frame that precedes the knock, both narrowbands are in transition low. That is the trigger in that instance for a value that is a bit too high for current conditions.
Thread Starter
Intermediate
Joined: May 2009
Posts: 26
Likes: 0
From: Iowa
Thanks for the input! I tightened up my nitrous plate and it definitely helped the idle surge, you hit that one on the head. My clutch is starting to slip at the top of 3rd and 4th, so I've been pretty easy on it lately. Plan on putting a new clutch in this weekend, and starting the tuning process soon. (I'll have plenty of non-WOT time to work on tables). I've switched over to 93 octane now and I'll go ahead and adjust the knock sensitivity and report back when the clutch is broken in.
I appreciate the help.
I appreciate the help.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
It may have some KR down there in CL but it seems he's more concerned about WOT according to his own words