Shaun Quill

I've been running this car for about 4 yrs.now and it runs flawless,but I just started logging with my LT-1 Edit and on a short pass,only into 2nd gear,it picked up over 5000 knock counts.I'm sure this is false knock because I don.t think this thing would still be together after all this time if it was pinging that bad. The timing and fuel curve are still factory,and I run good fuel,so,I don't know what gives. This thing has tons of runs on it and it runs better all the time.Any thoughts on this? Thanks, Shaun.

RamAir95TA

I am pretty sure the knock counts are cumulative. You should be more worried about knock retard.

Shaun Quill

Yeah it is retarding the timing,when I Lean on the converter it goes up to 43 total and drops to 34-35 when you punch it.I thought about unplugging the knock sensor if I can just to keep the car consistent-I don't know.I should probably leave it alone and just run it,but I want to build me a 383 so i figure I better learn to tune it.I never had an injected car before,so its all pretty new,I appreciate your input though Joe,Thanks. Shaun

Kevin Blown 95 TA

Our cars have aggressive timing. The deal with false knock is that first you have to prove it's false knock. Some race gas will help there. Octane booster - not really good enough for that purpose. If you still mix some 100 unleaded with your gas and still have knock you have to see what is causing it. Usually, the cars will retard a few degrees on shifts or launch, which is normal, but they shouldn't be doing it all the time. The Piezo crystal in the knock sensor doesn't last forever, either so the sensor may be at fault, or possibly the wiring going to the PCM from the sensor is leaning on a header. The sensor needs to be torqued to specification wth the proper sealant on the threads. Noisy valve train can do it. Exhaust leaks. Maybe you got carbon buildup and low octane gas. You have to see what the problem is before detuning it. I actually increased the timing retard on my tune to protect my engine, and it's still blazingly fast. You can eliminate the retard and run that way, but f you get it working right, it's actually a pretty sophisticated system and will protect your engine. One thing you can do is make the timing come back in faster if the PCM retards it so it recovers at a faster rate. Some of us also tried using the LT4 OBD2 modules in the PCM since those engines were set up with noisier roller rockers and supposedly had more false knock suppression, but I'm not sure how much that actually helped.

RamAir95TA

What you can do to determine if it's false or real knock is to head down to Cecil and put several gallons of 100-octane in (expensive, I know). If the knock goes away you know the KR is real. If it stays it's more than likely false, and you can have the KS desensitized in the tune or begin tracking down sources of false knock, like exhaust leaks, high voltage wires passing too close to the sensor, loose motor mounts, etc.

Unplugging the knock sensor will put the engine into a fit and pull timing in order to protect itself.

Ever make it down to Cecil? I'm heading down there in 2 weeks. You're booking for such little mods.

EDIT: Kevin tree'd me...

Kevin Blown 95 TA

As slow as I type, that ain't saying much for you, but it's good to win a race now and then

Injuneer

Does your data log actually show any knock retard? It isn't unusual to see the knock counts increment without getting any actual knock retard. If you don't have knock retard, you don't have a problem.

Shaun Quill

I appreciate the help fellas,i'm gonna keep an eye on it.Yeah Joe i do run alot at Cecil County,so I may try me some Cam 2 and see what happens,i'll have to look you up down there,I saw your video so I know what your car looks like,mines white with a black top. I'll post some results after I do some tinkering but like I said, Thank you guys very much-Shaun