LT4 Knock Module Installation
Why do this Modification? Basically, the LT1 knock module in our cars (1994-1997 LT1's) is too sensitive and is subject to picking up "false knock". What happens is when the computer thinks it's picking up knock, it starts retarding timing. The knock module can cause your timing to be retarded up to 22 degrees. This results in a serious loss of performance.
False knock has been reported by most at the high rpm end (who have Scanmasters, Diacoms, and other monitoring devices), which is usually indicated by your car "searching" and "surging" under WOT, and during wheel spin and shifting. Even a noisy valvetrain and headers will set off false knock. I know in my particular case I was seeing up to 11 degrees of timing retard due to false knock under normal acceleration. I attribute that to the loud exhaust and possibly vibration from the supercharger. The general consensus seems to be that if you run 93 octane gas and are normally aspirated, you should have no knock whatsoever.
In comes the LT4 Knock Module.... the Knock Module is what interprets the signal from the Knock Sensor in the side of your engine block. The LT4 engine is a normally "noiser" engine due in part to roller rockers in the valvetrain. Engineers did a much better job on the LT4 KM to "listen" for true knock and to weed out the normal engine noises. The results of installing the LT4 KM in the ECM on an 1994-1997 LT1 engine have been anywhere from "didn't notice much of a difference" to "WOW!". It certainly helped in my case. The typical result is smoother acceleration and no "searching" at high rpms. All this while still being able to sense true knock. Basically, the more you mod your car starting with the exhaust, the more susceptible you are to false knock.
LT4 Knock Module (not to be confused with the Knock Sensor which is installed in the side of the engine block.) I got mine through Lambert Pontiac at (800) 711-2793, Part No. 16214681 for about $27 US. (My old KM is pictured right) Installation takes about 10-15 minutes. #1 Disconnect your negative battery terminal first... or remove the fuse from your fuse box labeled "PCM" then unbolt the computer from the passenger side fenderwell. I used a 10mm socket with 3" extension. #2 Carefully remove the computer and lay it on it's side on the fenderwell. The wires connected to it are plenty long to completely pull it out. #3 Remove the two small bolts from the cover on the top of the computer using a Torx driver. I used a T-20 size Torx. Gently pry up with a small screwdriver if necessary. #4 Squeeze the two tabs together and remove. Replace with new LT4 module. Button it all back together and carefully place the computer back. Leave the battery disconnected for at least a good 15-20 additional minutes, then reconnect it. This will reset the computer. You're done!
