Knock Sensor ?
Thread Starter
Safety Car
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
Knock Sensor ?
I read that the LS3 Knock Sensors can be over sensitve. After X amount of K.S. triggers, does the ECM revert to 89 octance tune to prevent further triggering? Does the ECM return to 91 octane after you fill up at the gas station?
What can be done to reduce the over sensitive Knock Sensors?
What can be done to reduce the over sensitive Knock Sensors?
Last edited by Mike's LS3; Jun 6, 2010 at 01:32 PM.
Former Vendor
Joined: Jun 2009
Posts: 603
Likes: 0
From: Tampa FL
Yes the LS3 knock sensors are sensitive. If the computer sees Knock it will revert to the Low Octane table, it will stay there for a certian amount of time with our seeing Knock before it moves back to the High Octane table.
You can desensitize the knock sensors through the tune, but i would only recommand doing that if you know that the Knock is false and not real.
Ian
You can desensitize the knock sensors through the tune, but i would only recommand doing that if you know that the Knock is false and not real.
Ian
Drifting
Joined: Dec 2009
Posts: 1,404
Likes: 7
From: Malverne New York
Yes the LS3 knock sensors are sensitive. If the computer sees Knock it will revert to the Low Octane table, it will stay there for a certian amount of time with our seeing Knock before it moves back to the High Octane table.
You can desensitize the knock sensors through the tune, but i would only recommand doing that if you know that the Knock is false and not real.
Ian
You can desensitize the knock sensors through the tune, but i would only recommand doing that if you know that the Knock is false and not real.
Ian
Thread Starter
Safety Car
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
Thanks guys for your responses. I use only tier 1 gas, Chevroon 91 octane. Infineon raceway is nearby, which has unleaded race gas. I will try some and see what happens.
No codes are flashing, but I need to have a look at my oem tune to determine if I am getting any burst knock, false knock or real knock.
No codes are flashing, but I need to have a look at my oem tune to determine if I am getting any burst knock, false knock or real knock.
Thread Starter
Safety Car
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
Racer
Joined: Mar 2006
Posts: 281
Likes: 4
From: Houston TX
You will get false knock if you get wheelspin as well.
I tuned a LS3 the other day on the dyno and was getting 1-2 counts of knock on a bolt on car with 24* of timing. After 2 pulls, I had dropped the timing down to 21* and I was still getting some. While I was driving the car up to speed I noticed that the muffler in the rear was rattling loudly against the frame. Then I found out that each knock event was tied to the rattle of the muffler.
I looked at his exhaust and the x-pipe was welded to the muffler. Whenever I see this on cars, it always brakes exhaust hangers because it doesn't allow the exhaust to flex when the engine torques over so it's not a good idea.
I turned down the knock sensors slightly and it fixed the problem.
I tuned a LS3 the other day on the dyno and was getting 1-2 counts of knock on a bolt on car with 24* of timing. After 2 pulls, I had dropped the timing down to 21* and I was still getting some. While I was driving the car up to speed I noticed that the muffler in the rear was rattling loudly against the frame. Then I found out that each knock event was tied to the rattle of the muffler.
I looked at his exhaust and the x-pipe was welded to the muffler. Whenever I see this on cars, it always brakes exhaust hangers because it doesn't allow the exhaust to flex when the engine torques over so it's not a good idea.
I turned down the knock sensors slightly and it fixed the problem.
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
Thread Starter
Safety Car
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
If the knock sensor, false or real, are triggered, will it throw a code. What can I use to determine that K.S. have triggered. I have a Actron code reader, will it show up on there?
If not, would I have to buy a tuners program, like HP, to read the file on the ECM?
If not, would I have to buy a tuners program, like HP, to read the file on the ECM?
