False knock help? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

larry_g · 12-24-2015, 10:21 PM

I am getting some fairly consistent knock retard (4-8*) around 3000 rpm and again around 5000 rpm during WOT runs in 3rd gear. This is happening with three different tunes, the stock 93 tune (SCT X4) and two mail order tunes from reputable vendors. Car is stock except for a Roto-Fab intake and a generic oil separator on the PCV line. Always use 93 octane.

I plan on trying an octane booster to see if that makes a difference, but I am beginning to agree with the suggestion that it might just be false knock, even though I am not seeing or hearing anything obviously loose.

Even if it is false knock, it's still pulling timing, and therefore not running to it's potential. Any thoughts on what I should be checking more closely as a source?

CamaroDreams76 · 12-25-2015, 02:11 AM

Same thing here. Stock tune thought. I haven't found the issue on mine. Nothing over 5 degrees of timing for me.

SRTKILLER · 12-25-2015, 08:24 PM

Try pulling some timing out of it and see if your still getting KR under wot. If you pull timing out of it and the knock goes away that could tell you that it's true knock. Could also be a bad sensor giving a false reading.

larry_g · 12-25-2015, 09:37 PM

I can't adjust the timing on the mail order tunes but I could on the stock one. I'll have to try that tomorrow.

The only thing I found loose was the vacuum pipe for the NPP exhaust. I zip tied it to the A/C line near it and the knock retard lowered but didn't go away completely.

I was also thinking that I've only seen it in 3rd gear. I didn't see it in 2nd and I haven't run it in 4th, but I'll need a different stretch of road to do that.

CamaroDreams76 · 12-29-2015, 01:52 AM

3rd and 4th is where I get the higher knock readings. 2nd is really low at about 0.8.

larry_g · 12-29-2015, 01:49 PM

A couple of bottles of Lucas octane booster in a full tank of gas got rid of almost all of the knock retard on the tuner maps. My guess is that our 93 octane isn't that good so I'm going to see if tuning for 91 works better.

sixt3denied · 12-29-2015, 03:24 PM

I have the same exact problem. I'm running a 75 shot. I'm seeing around 8* knock retard at the very top of 3rd gear, right before the transmission shifts. I use 93 Octane and Royal Purple Octane booster or NOS Octane booster. Both claim to boost 3 FULL points.
I am thinking it is actually Burst Knock (Explained to me as follows: engine sees rpm flying up and predicts that knock is coming, so it initiates knock retard and pulls timing, like bracing yourself before being punched in the stomach).

I read that a lot of people zero out burst knock with hp tuners. Awaiting some extra $$$ so I can buy a tune...

1KillerSS · 12-31-2015, 10:26 PM

I'm surprised you haven't tried pulling timing already, that would be my first step, considering everything's tight and rattle free.

Sent from my iPhone using Tapatalk

larry_g · 01-10-2016, 11:05 AM

Update: It looks like I have a problem with fuel pressure tapering off on WOT runs right when the knock retard is most intrusive. I was able to see this on more than one log. Once the weather gets better, I'm going to return it to the stock tune and see if the fuel pressure still tapers off. If it does, I'm thinking that it should still be eligible as a warranty repair as I have done nothing to the fuel system.

The thing I am still trying to figure out is the kPa to psi conversion on the data log. Using the google conversion calculator, the numbers on the chart make it look like I am only getting 20 psi and tapering off to 17. However, I found one thread where they mention that you have to take the SCT reading times 3 to get the actual pressure. This would mean it's running about 60 psi (normal) and tapering off to the low 50's (not normal). Does anyone have any experience with this?

Rhino79 · 01-11-2016, 07:21 PM

52 psi is normal at wot, the fpcm commands a lower pressure at higher rpm.

larry_g · 01-12-2016, 08:06 AM

Quote:

Originally Posted by Rhino79

52 psi is normal at wot, the fpcm commands a lower pressure at higher rpm.

When I was on tap-a-talk, I couldn't see that you are a tuner. I'm sure this won't come as a surprise, but I am getting conflicting information on this...

2014CamaroSSRS · 01-13-2016, 09:36 AM

make sure you're using GOOD gas, it makes a difference.. mobil, exxon, sunoco, amoco, bp, chevron are best brands to use, with mobil and exxon being the best..

NEVER use Shell, costco/bj's, mom-n-pop, or no-name brands, as it's crap gas that tends to cause a lot of knock retard...

elmayimbe · 01-13-2016, 06:25 PM

Quote:

Originally Posted by 2014CamaroSSRS

make sure you're using GOOD gas, it makes a difference.. mobil, exxon, sunoco, amoco, bp, chevron are best brands to use, with mobil and exxon being the best..

NEVER use Shell, costco/bj's, mom-n-pop, or no-name brands, as it's crap gas that tends to cause a lot of knock retard...

How do you know that those 2 are the best? i want to know . Curious.
Thanks

2014CamaroSSRS · 01-14-2016, 09:44 AM

personal experience, along with several thousands of others that I've seen data logs for... can always tell when someone is using shell or other crap gas by their data logs.. lot of knock retard throughout the whole log...

12-24-2015, 10:21 PM	#1
larry_g Drives: 2014 1SS/1LE Join Date: Nov 2015 Location: Louisville, KY Posts: 826	False knock help? I am getting some fairly consistent knock retard (4-8*) around 3000 rpm and again around 5000 rpm during WOT runs in 3rd gear. This is happening with three different tunes, the stock 93 tune (SCT X4) and two mail order tunes from reputable vendors. Car is stock except for a Roto-Fab intake and a generic oil separator on the PCV line. Always use 93 octane. I plan on trying an octane booster to see if that makes a difference, but I am beginning to agree with the suggestion that it might just be false knock, even though I am not seeing or hearing anything obviously loose. Even if it is false knock, it's still pulling timing, and therefore not running to it's potential. Any thoughts on what I should be checking more closely as a source?

12-25-2015, 02:11 AM	#2
CamaroDreams76 Tri-County Camaro SWFL Drives: 2013 IOM 2SS/RS/1LE Join Date: Apr 2013 Location: South West FL Posts: 3,083 View My Garage	Same thing here. Stock tune thought. I haven't found the issue on mine. Nothing over 5 degrees of timing for me. __________________ Just bolt ons........ https://www.camaro5.com/forums/showthread.php?t=343023

12-29-2015, 01:52 AM	#5
CamaroDreams76 Tri-County Camaro SWFL Drives: 2013 IOM 2SS/RS/1LE Join Date: Apr 2013 Location: South West FL Posts: 3,083 View My Garage	3rd and 4th is where I get the higher knock readings. 2nd is really low at about 0.8. __________________ Just bolt ons........ https://www.camaro5.com/forums/showthread.php?t=343023

12-29-2015, 03:24 PM	#7
sixt3denied Drives: 2012 1LT/RS BLACK w NOS Join Date: Nov 2013 Location: New York Posts: 206	I have the same exact problem. I'm running a 75 shot. I'm seeing around 8* knock retard at the very top of 3rd gear, right before the transmission shifts. I use 93 Octane and Royal Purple Octane booster or NOS Octane booster. Both claim to boost 3 FULL points. I am thinking it is actually Burst Knock (Explained to me as follows: engine sees rpm flying up and predicts that knock is coming, so it initiates knock retard and pulls timing, like bracing yourself before being punched in the stomach). I read that a lot of people zero out burst knock with hp tuners. Awaiting some extra $$$ so I can buy a tune... __________________ BBK CAI, Dynomax Ultra Flow Exhaust, Vitesse Throttle Controller, 3M Dark Tint, BMR Subframe Connectors, BMR Drive Shaft Tunnel Brace, Bosch Brakes, Ny-Trex Triple Threat System, Glowshift NOS Gauge, Innovate LC-2 Wideband AFR Gauge, GM Strut Tower Brace, Elite Engineering Catch Can, Heritage Grill, Custom LFX Emblems, BAFX Bluetooth OBDII Interface, Torque Pro Logging, Big Worm Graphix Spears & Stripes,Niche M117 Misano Wheels, MGP Caliper Covers

12-31-2015, 10:26 PM	#8
1KillerSS Too much is never enough! Drives: AGP TT SS [COTW] 4/20/15 Join Date: Feb 2014 Location: Toledo,OH Posts: 4,149 View My Garage	I'm surprised you haven't tried pulling timing already, that would be my first step, considering everything's tight and rattle free. Sent from my iPhone using Tapatalk __________________ AGP TT kit, 54/57 Forged rotating assembly, Custom grind cam... Dual nozzle meth, ID850's, Livernois dual fuel pumps, ECS BAP, 25% UDP, 3 inch Magnaflow catback with X pipe, Mantic 9000 clutch, DSS 1000hp axles, DSS aluminum driveshaft, ZL1 rear end, solid subframe bushings, HE differential offset bushings, BMR Trailing arm, BMR toe rods, Lingenfelter LNC-2000,SJM Line Lock. 747 whp 714wtq *Build thread* http://www.camaro5.com/forums/showth...55#post8107855

12-25-2015, 08:24 PM	#3
SRTKILLER Drives: 2009 Cadillac CTS-V Join Date: Oct 2015 Location: Newcastle Posts: 79	Try pulling some timing out of it and see if your still getting KR under wot. If you pull timing out of it and the knock goes away that could tell you that it's true knock. Could also be a bad sensor giving a false reading.

12-25-2015, 09:37 PM	#4
larry_g Drives: 2014 1SS/1LE Join Date: Nov 2015 Location: Louisville, KY Posts: 826	I can't adjust the timing on the mail order tunes but I could on the stock one. I'll have to try that tomorrow. The only thing I found loose was the vacuum pipe for the NPP exhaust. I zip tied it to the A/C line near it and the knock retard lowered but didn't go away completely. I was also thinking that I've only seen it in 3rd gear. I didn't see it in 2nd and I haven't run it in 4th, but I'll need a different stretch of road to do that.

12-29-2015, 01:49 PM	#6
larry_g Drives: 2014 1SS/1LE Join Date: Nov 2015 Location: Louisville, KY Posts: 826	A couple of bottles of Lucas octane booster in a full tank of gas got rid of almost all of the knock retard on the tuner maps. My guess is that our 93 octane isn't that good so I'm going to see if tuning for 91 works better.

01-10-2016, 11:05 AM	#9
larry_g Drives: 2014 1SS/1LE Join Date: Nov 2015 Location: Louisville, KY Posts: 826	Update: It looks like I have a problem with fuel pressure tapering off on WOT runs right when the knock retard is most intrusive. I was able to see this on more than one log. Once the weather gets better, I'm going to return it to the stock tune and see if the fuel pressure still tapers off. If it does, I'm thinking that it should still be eligible as a warranty repair as I have done nothing to the fuel system. The thing I am still trying to figure out is the kPa to psi conversion on the data log. Using the google conversion calculator, the numbers on the chart make it look like I am only getting 20 psi and tapering off to 17. However, I found one thread where they mention that you have to take the SCT reading times 3 to get the actual pressure. This would mean it's running about 60 psi (normal) and tapering off to the low 50's (not normal). Does anyone have any experience with this? Attached Images

01-11-2016, 07:21 PM	#10
Rhino79 Drives: 2010 Camaro SS L99/Auto Join Date: Jul 2011 Location: Cabot, AR Posts: 2,827 View My Garage	52 psi is normal at wot, the fpcm commands a lower pressure at higher rpm.

01-13-2016, 09:36 AM	#12
2014CamaroSSRS Account Suspended Drives: 2014 Camaro SS - 2SS, RS Join Date: Jan 2014 Location: CT Posts: 90	make sure you're using GOOD gas, it makes a difference.. mobil, exxon, sunoco, amoco, bp, chevron are best brands to use, with mobil and exxon being the best.. NEVER use Shell, costco/bj's, mom-n-pop, or no-name brands, as it's crap gas that tends to cause a lot of knock retard...

01-14-2016, 09:44 AM	#14
2014CamaroSSRS Account Suspended Drives: 2014 Camaro SS - 2SS, RS Join Date: Jan 2014 Location: CT Posts: 90	personal experience, along with several thousands of others that I've seen data logs for... can always tell when someone is using shell or other crap gas by their data logs.. lot of knock retard throughout the whole log...