yzblue125

what are they?why does it seem like everyone upgrades them. i feel like a dummy asking this question but anyway, thanks!

chrisn

search my friend, you will save yourself some harrasment.

deputydough

yes, you will get harassed. but, ask what free mods are out there and you will get 6 pages of response. basically it detects knock and predetonation in the motor and pulls timing to stop it. it keeps you from fragging your engine with detonation. most people upgrade to a less sensitive KM when they go with certain engine mods because it is noisy enough to fool the KM and pull timing. even an exhaust leak can cause it to pull timing. then you have less HP. now mind you this a basic response from less than an expert. but, i hope i helped some.

yzblue125

thanks now i know,actually i found a good article on them on the trans am website.

Dave '97 Z28 M6

There's a couple of components at work here:

1. The knock sensor. This mounts on the engine and is essentially a piezoelectric "microphone" that picks up vibrations from the engine.

2. The knock module. This is a replaceable component of the computer (PCM). It "filters" the signal from the knock sensor, and passes onto the PCM what it perceives as genuine engine knock (and not ordinary, benign vibrations).

3. The PCM, based on input from the knock module, may retard spark advance in an attempt to reduce the knock condition (whether it's real or not).

There's only 2 different knock modules for the LT1 PCM - the original, and the LT4 knock module. The LT4 module is not less sensitive to knock, it's just a more discriminating filter designed to prevent the noise from the LT4's factory-equipped roller rockers from causing false knock. Many people use the LT4 KM in their modified LT1's, to overcome false knock issues due to valvetrain noise. And if that's not enough, the PCM can be reprogrammed to be less responsive to knock.