If you folks don't have a scanmaster or some kind of scan tool or program, and you race, GET ONE! I never even knew my car had knock retard till I got my scan master.

Well anyway. The car seems to always get 4 degrees knock retard as soon as it goes into 2nd in WOT. And it pisses me off, because the car isn't running lean. I already have the lt4 KM, and madz28 tune, which I'm guessing should help out.

But I have been thinking that this knock retard has to be hurting my performance. So what do you guys think about this. I was thinking about getting my knock sensor deleted and installing one of these .... http://www.jegs.com/cgi-bin/ncommerc...67&prmenbr=361

That way, I can tweak it, so it isn't so dang sensitive. And that way if I somehow do get knock, it will warn me, and I will let off the accelerator, and back off.

This way I won't be getting all this knock retard for the false knock. I know its gotta be hurting my e.t.'s somewhat.

What do you guys think?

Mike

 

I'd first prove that the knock is false. Run 100 octane gas, if the knock stays at the same level, then it's most likely false knock.

 

How much should run? I have added 3 gallons of 100 octane to a full tank of 93, and didn't see much of a difference. It seems like it happens between the dang shifts.

Fred said he sees this happen in between shifts on a manual. But I don't know if its normal for this on autos as well.

Mike

 

I'd run the tank low then add 3 gallons of 100 octane. It's only going to take a short amount of driving to determine if the knock is still there, then you can top off the tank.

 

I'lll give that a shot.

Does the resitor trick work on the 97 knock sensors? If so which resistance would I want?

THanks,
Mike

 

From Brent Franker's website:

http://www.charm.net/~mchaney/knock.gif

 

Where can I pick up 100 octane gas?

 

I have a scanmater now and finding I get knock on 92 octane.So doubt it was real.I checked and found my exhuast pipe hitting the crossmember that accounted for some of my knock.I still seem to get some but my o2s sometimes look very low.I think my fuel pump is weak or possibly its a fuel filter problem.I changed out filter last year or year before but to off brand went with gm this time.

Anyway to find out if you don't have 100 octane go to local paint store and buy gallon of xylene or toluene.Add it to a couple gallons of gas.Instant 100 octane but don't get it on your paint! Buick and other turbo guys use it all the time.Is safe for your engine in 30% or so ratio.

I have the lt4 km in my car too and no real mods on it so now way it should be getting any knock even at 92.Weather is maybe 60 to 70 F here so not 110 or anything crazy.

And for my current mods have magnaflo catback,tb bypass,hpp but tuning out,maft but it seems even if set it rich than still get the knock and lean readings sometimes,g2 induction,holley filter,airfoil.
I have disconnected my egr not sure if that can make it run lean but don't think it even has an effect at wot where my knock happens.

I plan on new fuel filter shortly and will be putting in a new racetronix fuel pump setup since have a zex nitrous kit but no way put that in until this knock and lean readings are figured out.

 

Hmm, It doesn't say if that will work on the 96-97 cars. And from what I remember reading they had a different knock sensor on the 96 and 97 lt1's.

ibanez6rg, If they don't sell it at your local or nearbye race track. You can actually buy small and large drums of it. Just be sure not to get the real serious stuff that is leaded. Because it can damage your o2 sensors.

Anyone else have a cure for getting rid of the false knock, besides having it deleted from the pcm?

I may just buy the MSD unit, and give it a shot.

Mike

 

The knock sensor is a tuned microphone. Tuned being the real important part. The MSD unit may or may not respond to the frequncy that corresponds to knock on your engine. A change to forged pistons with more running clearance can make the ECU think it sees knock. The 1-2 shift would be a spot that many engines could ping. Its a very high load and the engine is now accellerating slower due to the ratio change. I would unplug the sensor and make a pass and check the et. 4 degrees isn't very much retard, so if the ECU is only taking out 4, then the ping was mild and shouldn't do damage to your combo if it isn't blown or on the bottle.

My suggestion to unplug the sensor may be a bad idea. Some computers will advance the timing up to knock and then back off always trying to maintain maximum advance to the set limit. I have no working knowledge of the LT1 ECU and as such can't say whether the timing will go way adavanced or not.

 

Thanks for the info Mark. I guess next time I am the a track I can experiment. Then I would have raw data to help me decide.

So does anyone else on here know if the resistor trick will work on the 96 and 97 knock sensors like it does on the older style lt1 knock sensors?

Mike

 

Nobody around me sold 100 octane either (except for the tracks, which really aren't that close) so I went to Lowes and picked up a can of Xylol/Xylene. I think its supposed to be equivalent to like 116 octane by itself or something. With about 1/8th of a tank of 95 in my car and that stuff in there I still got the same KR. So when I had the MadZ28 tune done I just had the knock sensor disabled completely. It's risky...but I'm a risky type of guy...lol

 

use a gallon of xylene from a paint store, determine if it is false knock. good luck