what does a LT4 knock module do

[redbird94]

what does it do?

[Red97ta]

The Lt1 knock module is to sensitive (detects detonation), and tells the computer to pull out to much timing. The Lt4 module is more accurate and alows the computer to use more timing in the upper rpm part of the power band.

[Injuneer]

Think of it as a "filter" that eliminates signals coming from the knock sensor that are caused by known noise makers, like the Crane Gold 1.6 roller rockers that were standard equipment on the LT4 engine. The knock module is simply a filter to allow (hopefully) only noise patterns that are representative of "true" engine knock/detonation to reach the PCM, and allow it to retard timing to eliminate the knock.

[Joe 1320]

There are two parts of the system. The knock sensor itself that is screwed into the block and the knock module located in the PCM. The knock sensor "listens" to the mechanical noises, the knock module filters out mechanical sounds like roller rockers and such that don't have the same harmonics as detonation. It can still be fooled, but the LT4 knock module does a better job of filtering out incidental noise like tailpipe rattle that causes a reduction of timing when the sensor picks it up. I noticed a couple of degrees knock retard on a gearshift with the stock module. There was also a kind of flat spot immediatly during and after the gear change until the timing returned. Now with the LT-4 knock module, the car pulls strongly right through the gear change and no knock retard. Definately a worthy mod.

[alenstein]

So where does one go about getting one, can you just replace the sensor it self in the block or do you also need the module at the PCM?

[Injuneer]

Originally posted by alenstein
So where does one go about getting one, can you just replace the sensor it self in the block or do you also need the module at the PCM?

Unfortunately, the 1993 LT1 ECM does not use a knock "module". Only the 1994-97 PCM's have a slot for the knock module. In the 1993, if you suspect you are encountering "false" knock from extraneous mechanical systems, you will have to consider "desensitizing" the knock sensor itself. There is an online procedure available to tell you how to do this.

I would not worry about knock retard unless you have had the ECM scanned under WOT load to verify that you are getting any.

[MN6WS6]

Here's a question I have, should I get one of these for my car with a 5176 nitrous kit on it? We have 93 octane here, and I have all the safety stuff, but I'm just wondering if it might be pushing the envelope putting it on a nitrous car with no timing control other than the computer.

[Joe 1320]

Like Fred said, in order to be determine whether a LT4 knock module is going to help, you must run a scanner at WOT to determine whether you are getting any knock retard or not. If you are getting knock retard, is it real knock due to fuel quality or tuning issues, or is it false knock like the exhaust banging against a mount that the regular module hears as knock.