False Knock?
Thread Starter
Drifting
Joined: Sep 2008
Posts: 1,630
Likes: 3
From: Aiea Hi.
False Knock?
So, the car goes in today to BSM for the A&A install at 12PM....I'm all freaked out because I've never left it out of my site since I bought it. I'm like most of you here that has worked VERY hard my whole life to have such a nice ride. ANYWAY, the guys at BSM say that they are going to dyno the car to make sure nothing is wrong to start with, then go ahead with the install.
Two hours later, I get a call from Shaun (really nice guy), Bodies main guy who tells me that the PCM is locked. GAH! So it costs me an extra C-note right off the bat to have the LPE tune unlocked.
I go down to check out the tune, and Bodie shows me two places on the graph with false knock. One @ 4200, the other at 4900. He didn't seem worried about it, but said he was going to look further into it.
What the hell is false knock, and what is it doing in my car?
Two hours later, I get a call from Shaun (really nice guy), Bodies main guy who tells me that the PCM is locked. GAH! So it costs me an extra C-note right off the bat to have the LPE tune unlocked.
I go down to check out the tune, and Bodie shows me two places on the graph with false knock. One @ 4200, the other at 4900. He didn't seem worried about it, but said he was going to look further into it.
What the hell is false knock, and what is it doing in my car?
Le Mans Master
Joined: Aug 2004
Posts: 5,259
Likes: 16
From: Monroe Township New Jersey
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
St. Jude donor in memory of jpee '14
False knock occurs when the knock retard is set off by something other than engine knock. Most of the time it happens with something metalic rubbing or banging around near the exhaust, engine bay or under the car.
I installed a complete Z06 exhaust on my car and noticed what appeared to be false knock on my HP Tuners scan. My axle over pipes were rubbing against the trans. Took a torch, pry bar and some header wrap.....no more false knock.
Your tuner should be able to locate it and fix it
I installed a complete Z06 exhaust on my car and noticed what appeared to be false knock on my HP Tuners scan. My axle over pipes were rubbing against the trans. Took a torch, pry bar and some header wrap.....no more false knock.
Your tuner should be able to locate it and fix it
Drifting
Joined: Feb 2007
Posts: 1,844
Likes: 12
From: Alpharetta Georgia
A lot of times false knock can be attributed to much to sensitive knock sensors. Even GM seemed to realize this from the 08 LS3 ECM as they modified the attack/decay rate and I believe even the sensitivity on the 09 LS3 ECM.
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
How did they know it was False knock and not real? The reason I ask is I thought I had some false knock at those rpm's. I mixed in some 100 octane gas to get my overall octane rating to around 95 and the knock went away. That means it was real knock.
Thread Starter
Drifting
Joined: Sep 2008
Posts: 1,630
Likes: 3
From: Aiea Hi.
Good question.... I'll have to bring that up to him in the morning.
Thanks!
