Occasional engine knock
Thread Starter
Instructor
Joined: Jul 2012
Posts: 202
Likes: 35
From: Anahiem CA
Occasional engine knock
Hello everyone I have a question about an occasional knocking sound coming from my engine on my A8 2017 Z06. Let me start out by saying I have owned 2 GS’s C6 and C7 before I purchased my Z06 and I haven’t heard this sound on those 2 vehicles. This is my daily driver because my round trip to work and back is only 8 miles and no freeway. I always drive with the radio turned down and window down (cause it sounds badass) so I’m hyper sensitive to any odd noises coming from the vehicle. I’ve been to several track days and autocrosses and never noticed the knocking noise then. Which leads me to my question of, has anyone else heard this knocking sound? Kinda sounds like bad gasoline but I always run 76 premium fuel. Lastly it really only seems to happen if I’m in a higher gear and I get on it, not floor it but enough to scoot around slower vehicles.
Im not freaking out to much about it because I have a GMEPP platinum warranty for 7yr or 100,000 miles.
I would love to hear your thoughts on this.
thanks
Im not freaking out to much about it because I have a GMEPP platinum warranty for 7yr or 100,000 miles.
I would love to hear your thoughts on this.
thanks
Melting Slicks
Joined: Aug 2016
Posts: 2,761
Likes: 1,016
From: MOUNTAIN HOME Arkansas
I’ll take you really do mean “knocking” versus “tapping” like valves. Couple of questions, you said premium 76 gas, is that a brand & do you always use a minimum of 93 octane? Any lower is not OK except in emergencies for this supercharged beast. Also will the knocking occur with tranny in D or also in manual mode (paddles)? Too high a gear in either case could cause lugging/knocking. Thanks 😊
Last edited by madrob2020; Feb 25, 2020 at 02:30 PM.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 202
Likes: 35
From: Anahiem CA
Thanks for responding.
So now that you mention it, I just fueled up and premium Gas here in CA is 91 octane and 76 is a fuel brand here that has higher octane in the lower rated fuels. As to the was it in “D” I believe I’ve heard it in manual and automatic with me in a higher gear. If I’m supposed to be running 93 octane maybe I will need to get some octane boost additive when I fill up.
So now that you mention it, I just fueled up and premium Gas here in CA is 91 octane and 76 is a fuel brand here that has higher octane in the lower rated fuels. As to the was it in “D” I believe I’ve heard it in manual and automatic with me in a higher gear. If I’m supposed to be running 93 octane maybe I will need to get some octane boost additive when I fill up.
Melting Slicks
Joined: Aug 2016
Posts: 2,761
Likes: 1,016
From: MOUNTAIN HOME Arkansas
Just double checked my’19 Z OM to verify the octane required. I previously had a’16 Z so not sure if that changed. OM says 91 MAY be used if 93 unavailable but with reduced performance/fuel economy. There is also a CAUTION section listing fuel ingredients that must not be in the fuel in ANY amounts (which might also be found in some fuel additives/octane boosts-my words). Can’t find any 93 nearby? Also OM states use Top Tier fuels (google that). Your 76 brand may not meet that requirement. Good luck 👍
Last edited by madrob2020; Feb 25, 2020 at 04:24 PM.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 202
Likes: 35
From: Anahiem CA
Thanks to all for your input on this subject. Thanks for the tip on the location for the 100 octane laserdude, love the name by the way. Wish I knew this before hand, but hey live and learn.
thanks
thanks
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Thread Starter
Instructor
Joined: Jul 2012
Posts: 202
Likes: 35
From: Anahiem CA
UPDATE
Hello All
So I went and filled up with some of that sweet sweet 100 octane nectar and I gotta say no more engine knock so far,and its running extremely peppy now. Hopefully I can find an alternative to using this fuel since it costs $9.99 a Gal. I guess I could use a splash of that and the rest 91 octane to give me 93 or 94 octane but there has got to be a better alternative or maybe that is wishful thinking. I wonder if anyone else in CA is having this same issue as well. Incidentally I am not running any mods other than an Attack Blue air filter in the stock intake assembly
Thanks for advice on this subject everyone.
Hello All
So I went and filled up with some of that sweet sweet 100 octane nectar and I gotta say no more engine knock so far,and its running extremely peppy now. Hopefully I can find an alternative to using this fuel since it costs $9.99 a Gal. I guess I could use a splash of that and the rest 91 octane to give me 93 or 94 octane but there has got to be a better alternative or maybe that is wishful thinking. I wonder if anyone else in CA is having this same issue as well. Incidentally I am not running any mods other than an Attack Blue air filter in the stock intake assembly
Thanks for advice on this subject everyone.
Melting Slicks
Joined: Apr 2019
Posts: 2,499
Likes: 1,165
From: Northern Wisconsin
It may be possible that your knock sensor is not doing its job as it should. Once engine knock is detected, the ECM is supposed to retard ignition until eventually the knock goes away. If the knock sensor is defective, there may have been a DTC code set, so I suggest checking for codes.
Melting Slicks
Joined: Apr 2019
Posts: 2,499
Likes: 1,165
From: Northern Wisconsin
Thread Starter
Instructor
Joined: Jul 2012
Posts: 202
Likes: 35
From: Anahiem CA
NEW UPDATE:
Good evening everyone hope you are all staying safe out there.
I took my car in today To the dealership and found out that the knocking noise was actually my supercharger going out. The service manager said there was a TSB on the 2017 Z06 for supercharger issues, I’m assuming related to a bearing. Part has been ordered and should be fixed in a week.
I wonder how many folks on this forum have encountered the same issue? Let me know.
Good evening everyone hope you are all staying safe out there.
I took my car in today To the dealership and found out that the knocking noise was actually my supercharger going out. The service manager said there was a TSB on the 2017 Z06 for supercharger issues, I’m assuming related to a bearing. Part has been ordered and should be fixed in a week.
I wonder how many folks on this forum have encountered the same issue? Let me know.
Pro
Joined: Mar 2018
Posts: 620
Likes: 91
From: Sacramento CA
NEW UPDATE:
Good evening everyone hope you are all staying safe out there.
I took my car in today To the dealership and found out that the knocking noise was actually my supercharger going out. The service manager said there was a TSB on the 2017 Z06 for supercharger issues, I’m assuming related to a bearing. Part has been ordered and should be fixed in a week.
I wonder how many folks on this forum have encountered the same issue? Let me know.
Good evening everyone hope you are all staying safe out there.
I took my car in today To the dealership and found out that the knocking noise was actually my supercharger going out. The service manager said there was a TSB on the 2017 Z06 for supercharger issues, I’m assuming related to a bearing. Part has been ordered and should be fixed in a week.
I wonder how many folks on this forum have encountered the same issue? Let me know.
Pro
Joined: Mar 2000
Posts: 729
Likes: 20
From: Pittsburgh, PA, USA PA
I have a 2015 C7 Z06 that I am currently tuning with hp tuners. I'm stock on a diablo 93 tune and I cannot get the car to stop knocking under load between 2000 to 4800 i have random knock on tip in during boost. Apparently, its a thing with Z06.
I removed the diablo 93 tune by going table by table, setting by setting, and removing it to the reference stock calibration file for C7 Z06. Same thing KR. Removed a bunch of timing from the high octane table. Doesn't matter still knocks. Then i find that "EVERY" 2015-2016 C7 Z06 has static knock retard configured for cylinder #1 only over the range 2000 to 4800. so what is happening is KR will always register happening due to that static knock. I chased my tail on this one a bit.
What i am actually doing is adding flex fuel, but on wanted to ensure my 93 tune was good before hauling off and adding E50 blend to my Z. the KR was a concern obviously. In short, that KR that was showing on the Diablo 93 tune was fake knock due to GM adding static retard to Cylinder #1 Booooo. I chased my tail on this one a bit.
I removed the diablo 93 tune by going table by table, setting by setting, and removing it to the reference stock calibration file for C7 Z06. Same thing KR. Removed a bunch of timing from the high octane table. Doesn't matter still knocks. Then i find that "EVERY" 2015-2016 C7 Z06 has static knock retard configured for cylinder #1 only over the range 2000 to 4800. so what is happening is KR will always register happening due to that static knock. I chased my tail on this one a bit.
What i am actually doing is adding flex fuel, but on wanted to ensure my 93 tune was good before hauling off and adding E50 blend to my Z. the KR was a concern obviously. In short, that KR that was showing on the Diablo 93 tune was fake knock due to GM adding static retard to Cylinder #1 Booooo. I chased my tail on this one a bit.
