What is it? What does it do? Do I want one?

 

Its a small chip that inserts in the 94-97 PCMs, to filter out the mechanical noise associated with the Crane old roller rockers that were used in the 1996 Corvette LT4 engines. If you have "false" knock, causing the PCM to retard the timing, the LT4KM may help you eliminate that false knock, and the performance loss it causes.

 

thats not the constant "tick" i hear when I accelerate is it?(usually happens when its colder outside)

 

"Knock" gernerally occurs under heavier acceleration, but not at likely when the engine is cold. And you aren't likely to "hear" knock at all, since the knock sensor can hear it way before you can, and the PCM retards the timing until the knock is gone. If you can actually hear knock, you have a serious problem, but I don't think that's what you are hearing. If you know anyone with an OBD-II scanner, they can hook it up and watch for knock retard as you accelerate. That would provide a clear answer.

Ticks when the engine is cold are often exhaust gasket leaks.

 

Sometimes they are lifters that have leaked down a little, from the spring pressure still applied after shutoff, and when cold they take a few seconds to get pumped back up... Mine do that, normally clears up in about 20-30 seconds, depending on outside temp and oil thickness...

 

I had my knock sensor "desensitized" at Madz28.com. But i still fear that i have false knock and i wonder which is better... a lt4Km or the desensitized one?? hmmm.

 

Pretty much the same thing I hear. I'm told it can be done through the computer or with the lt4km. Did nothing for me that I could notice.

 

I think they are different things entirely.

I haven't seen a bin file from a car that was "desensitized" but based on what tables are available, I am guessing that what is done is to make the car pull less timing when it sees knock. I've seen threads on programming forums where people were told to "desensitize" by setting all the values in the knock retard table to zero. Doing that would mean you have no protection from real knock.

The LT4KM, on the other hand, makes the car see less false knock, but it will still pull timing by the stock amount when it hears (presumably real) knock.

 

I bought mine from www.gmpartsdirect.com for 37 bucks. I verified with scans that there is no knock or timing retard with this LT4 knock module. I didn't do a scan on the LT1 module so I don't know if I had any to start. I can say that there is none with the LT4 though.

David

 

Not the same. The LT4KM specificaly filters out known "false" signals, altering the PCM tables reduces the PCM's response to false AND true knock. One can't hurt your engine, the other can if the knock is severe enough.

On the other hand, engines ran for 40 years without knock sensors, and somehow survived without them, as does my engine.

 

Ok not really the same but from Ed Wright says any tuner can do the same thing without it. Ill dig up his comments on it later. That's why I thought it was the same. As for running without a KS I think youre a 110% correct. Never had one till I got a camaro and it's more of a pain than anything else.

 

So nothing wrong with LT4KM?

 

It's a waste of money. It won't fix anything. If ya have headers the sound inside the headers will trigger retard.
The LT4 KM will only react to what it's tuned for.
Do a search and put it on a switch with the resistor. if it's false knock.
I have run SBC since the '50's and no knock sensor and never hurt one but ya got hyper-u-craptic pistons in an LT-1 and that's what the factory is protecting with the knock sensor.

 

I could tell a huge difference when I installed my LT4 KM. I was getting around 11 degrees of retard with the LT1 KM and had none with the LT4.

 

whats the part number thru GM for the KS for the LT4?