I just got my pcm back from Ion and was looking at the list of things that was done to it. One item on that list was knock retard desensitizing. How does this differ than putting an LT4 knock module in? I was under the impression that this is what the LT4 KM did. Anyone help me out? Im wondering if its still worth getting me a LT4 KM.

 

Try asking Ion. If anybody is going to know, it is going to be the tuner. I'm sure he'll know the anwser.

 

I have NEVER had a LT4 KM do anything but cost ya money.
If ya got headers the internal sound of the exhaust will trigger retard so the LT1 that has been desensitized will do just as good.
If ya still get retard,a good while back, I suggested to put it on a 2 position switch with the resistor on one side for race night and the other side normal.
There have several who have done it and provided wiring diagrams as to how to hook it up. Might find it in a search.
I would try what ya have first though.

 

if you didnt get the tune and you have a madz28 tune how would you find out if its been desensitized? would he know? I would like to know this because i dont want my lt1 knock module retarding timing over nothing and causing me power. It does feel like i lose some power after a while

 

Call Ion and see.
The switch thing is VERY easy to do then ya will have the safety on a HOT day in traffic and no retard on a COOL race night.
GM put it there 'cause the hyper-u-crap-tic pistons won't take much detonation.

 

ill do a search on this switch thing.. i should only turn it off when im gonna race or im going for a spirited drive right? otherwise something could get damaged. And once its the timing is retarded it takes a while to go back to normal. If it gets retarded and then i turn it off does that set it back to normal or do i still have to wait?

edit* did a search and have another question... How do you find out if your getting knock? Do i need to get a scanner and see? And then how do i verify its false knock?

 

Do a search on the board ya will find the info.
If ya get it out of the retard/detonation situation the timing comes back in a few revs. If the engine is still in detonation it won't. If ya flip the switch while it is under load and detonating then it will/should detonate rather than pull timing,which is not a good thing.
Ya also have what is called false knock. That is it's not the engine detonating it is another noise causing the retard. The only way to tell is put some 100 octane unlead in the tank and see if the knock is still there. If it is usually it is something else or your tune is way screwed up.

 

You don't need an LT4 KM. Heck, those knock modules were designed for a dual knock sensor OBD2 LT4 Y-car and most people run them on just about any variety of LT1 or even L99. That module is NOT "less prone to pickup false knock" as many people think. It's simply designed for a different setup and it just happens to not pick up as much retard in some cases. I'm sure if you used some random Impala or some other module, you would achieve the same results or better. It's not a more efficient module, but rather a crude way of desensitizing similar to the resistor mod some people do. It doesn't work all the time either. It's also possible that you may not have knock at all.

In other words, you will be fine with the programmed "desensitizing" since that is more permanent and more consistent. It's still a crude way of desensitizing, but a bit more sophisticated than the others. Not that the actual knock retard system is any better. It shouldn't pick up false knock in the first place.

 

great!! thanks Ion! can't wait to get my starter and get this thing back on the road!

 

how can you tell if your knocking? I know if its real knock you can hear it but how can you really tell if your getting false knock? Ill have to ask Madz28 to see if he desensitizes it in his tunes

 

You won't even hear it if its knocking from "real" knock.... the knock sensor hears it before you can, and the PCM retards the timing. If you hear it, your in big trouble, or someone has defeated the knock sensor or severely desensitized it.

The way to tell what's happening is to put a scanner on it and monitor knock retard. If you're getting retard, then you need to figure out if its real or "false". First step is to load it up with some 100-octane unleaded, and see if the knock retard goes away.

 

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Ya also have what is called false knock. That is it's not the engine detonating it is another noise causing the retard. The only way to tell is put some 100 octane unlead in the tank and see if the knock is still there. If it is usually it is something else or your tune is way screwed up.


Ya didn't read my post and Fred listed it too.

 

alright ill have to see if i can get access to a scanner.. and then ill need to find out where to get 100 octane. im also gonna contact madz28 to see if he desensitizes it in his tunes.

 

I've already replied above and you also have it listed on the sheet you got with the PCM.

 

didnt realize you were madz28.. how bout that. I didnt buy the tune from you the person who owned the car before me did and he doesnt have the sheet that your speaking of. So i was just wondering if its something you do regularly or if it has to be requested.