LS4 knocking
11-18-2013, 11:22 PM
#1
Teching In
Thread Starter
Join Date: Apr 2013
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
LS4 knocking Before I actually post what I think is wrong with my car, please take a look at the image. I am having low end rpm knock. I don't hear any knock. What do you guys think this is?
It is easy to see the knock right around 2200 RPM, top left. If you look at the speed graph(bottom right) you will notice the bright green line is rpm and i am cruising on the highway and it's knocking.
I have looked on this for quite a while and may have found a correlation.
Thanks
2008 Impala SS, Air Intake, Magnaflow exhaust, one level colder plugs, zzp high flow cat, catch can, 60K miles only one trans valve body replace so far.
It is easy to see the knock right around 2200 RPM, top left. If you look at the speed graph(bottom right) you will notice the bright green line is rpm and i am cruising on the highway and it's knocking.
I have looked on this for quite a while and may have found a correlation.
Thanks
2008 Impala SS, Air Intake, Magnaflow exhaust, one level colder plugs, zzp high flow cat, catch can, 60K miles only one trans valve body replace so far.
11-18-2013, 11:33 PM
#2
TECH Addict
iTrader: (15)
Join Date: Aug 2002
Location: 78°14′46″N 15°27′56″E
Posts: 2,419
Likes: 0
Received 5 Likes
on
5 Posts
This is extremely common with these cars, especially on a stock tune with mods. Basically, once the torque converter is locked and you go into 4-cylinder mode, the KR goes way up. A decent tune from a reputable tuner will resolve this.
BTW- My car had a ton of KR before getting my DiabLew tune, but I never heard the car knock. I just knew it was there because I ran an Aeroforce Interceptor gauge set to report knock, and it was pretty constant.
BTW- My car had a ton of KR before getting my DiabLew tune, but I never heard the car knock. I just knew it was there because I ran an Aeroforce Interceptor gauge set to report knock, and it was pretty constant.
11-19-2013, 06:14 PM
#3
Teching In
Thread Starter
Join Date: Apr 2013
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
I forgot to say it has a 91 diablo with no DOD. My injector slope is set to -5 which get's my ltft in line. Well needless to say, my harmonic balance is wobbling at slow speeds and i believe when i let off the gas at cruise it causes knock. You can actually see some rubber sticking out from it. I have a feeling it's about to come out. I don't hear a noise at all. Could this introduce this kind of knock? As the harmonic balance goes bad in the ls4's so easily, i wonder if this could be the cause of a lot of peoples problems.
11-19-2013, 07:10 PM
#4
I forgot to say it has a 91 diablo with no DOD. My injector slope is set to -5 which get's my ltft in line. Well needless to say, my harmonic balance is wobbling at slow speeds and i believe when i let off the gas at cruise it causes knock. You can actually see some rubber sticking out from it. I have a feeling it's about to come out. I don't hear a noise at all. Could this introduce this kind of knock? As the harmonic balance goes bad in the ls4's so easily, i wonder if this could be the cause of a lot of peoples problems.
11-19-2013, 11:26 PM
#5
Teching In
Thread Starter
Join Date: Apr 2013
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
Well it looks like most knocking is when the LTFT is at 1.6 as seen in the graph (second on the top). Should i adjust the injector slope lower or is this where i mess around with PE? This is consistent on most of the graphs i generate. The KR as show goes from 0 to 6(note the dots) at 1.6 LTFT. It also may be on slight acceleration if i zoom in on my graph locally. I am still going to replace the balancer as i see rubber and it wobbles. Hopefully the new one doesn't wobble.
