bigshoe

iTrader: (2)

does that make sense? I have a 98, and I've been chasing KR forever, I did the following

1. bought some chemical from Home Depot and mixed it with my gas to make about 96 octane - still had KR (this was a couple years ago, car has more mods since then).

2. Took off my old ASP crank pully, there was speculation that the older pullies setoff the knock sensors - still had KR

3. Tried rearranging my exhaust, my flp headers come dangerously close to my G2 torque arm

4. Changed my intake and camshaft, installed the newer 6603 Knock Sensors, onlly to find out my previous sensors were ALSO 6603's - still had KR

5. Today I looked at the exhaust again, stinkin flp y-pipe is pressed against the torque arm, I say Eureka, realign everything, have a good 1/2"+ of clearence, take it for a drive - STILL HAVE KR

6. Finally get the ***** to play with spark table (I've been doing VE tuning on my SD tune that i started recently). this was after i modified KR recovery rate and decay rate (less KR, but still had alot of it). I was getting a consistant 4* at WOT, I decided to subtract this from my timing tables, did another log, still getting 4* in all the WOT cells, I subtracted it AGAIN just to be sure, i was getting riming in the 11-14* range BUT STILL GETTING ABOUT 4* OF KR.

i'm losing it here, its gotta be some type of harmonic in the engine, i dont think there is anything else I can try.

so my question is, if this was real KR, it should have disappeared when I subtracted timing - IS THIS ALWAYS TRUE????? if so, I'm just gonna kill the sensitivity and start adding timing blindly (since i may not be able to pick up real knock with desensitized sensors now - then i dont know when i'll be getting real KR from too much timing).

sorry for the long post, but I seem to be getting nowhere with this KR issue.

EDIT: I did a log with my stock spark table (i'm running SD with a close to dialed in VE table), and I set my Knock Sensor Global Gain vs MAP vs Cyl to ALL 4's (the entire table), that didnt log ANY KR then, but i guess i'm telling it to pretty much ignore KR? anyways, the car ran great, never felt 1st gear have so much power - it caught me off guard!

any comments/guidance is appreciated,
thanks in advance,
Miki

gametech

iTrader: (1)

You already answered your own question. If kr is the same with better octane and lower time, then YES, it is FALSE KNOCK. You are,however, correct in taking a cautious approach to determining this.

bigshoe

iTrader: (2)

right, i pretty much got that part, i may have been unclear in my rambling of the first post.

i'm more concerned with whatever is causing the bad harmonics, or whatever is going on in there, as in other possible damage - is my rotating assembly out of balance or something like that.

also, since i'm killing the Knock sensitivity, is it still safe to keep advancing timing? since i may not be able to really detect REAL knock due to too much advance.

I may just turn the knock settings back the way they were, and just start adding timing till i get changes, but with stock knock settings, my KR wasnt totally predictable, making it kinda hard to tell when real knock happens anyways. wish i didnt have this problem......

obZidian

iTrader: (2)

i am also with the same predicament...

Im getting bad knock everywhee, 98 also, and im almost done with it.

Im sure this is an extinguished topic, but im un sure how some of ya'll have fixed this false knock issue be it through tuning or replacing parts.

Anyone with this kind of info, please chime in....we all need a clear answer...

thanks

I have hp and this is what i think might be the problem...

my knock fast recovery rate vs rpm looks like this (oh, its rpm ontop vs rate on the left)

0 400 800 1200 1600 200 2400 2600 2800 3200 3600 4000-------------------8000
0.1/0.1/0.12/0.12/0.15/0.15/0.16/0.16/0.16/0.16/0.13/0.13/0.13/0.13/0.13/0.13/0.13

another file sent to me by another 408ci, 98 car and his table reads the similar but instead of .10 (for example) it reads .010, .012, .015 etc.

what this is telling me is that the knock, in my car, will cutoff later than the other 408ci'z. (is this right?) His attack rate is a little more aggressive but not enough i think to cause any real problems. if anthing, since my vlaues are lower in the attach rate (knock), than m car should aquire less knock.

So, am i close or am i just wasting key strokes.........

TT_Vert

iTrader: (12)

go get some unleaded race fuel to see if it goes away. Dont play chemist cause you dont know exactly what octane you have. Also keep in mind when in SD tuning mode, you need to modify the secondary timing table, not the primary.

Dave

Phoenix 5.7

iTrader: (7)

98s are notorious for false knock. i dunno how to fix it though. try a search for 98 false knock and someone may have something

Wnts2Go10O

iTrader: (12)

with a 99+ ecu

bigshoe

iTrader: (2)

I dont see how the 99+ ecu will fix anything, given that it would require a 99+ harness for the different pin-out and possibly even something else.

it would be nice to have a real fix for this. I dont like the idea of desensitizing the knock sensors so much that they may not do what they were intended to do in the first place.

any other options? and yes i've searched this scores of times over the years, I just cant find a good solution anywhere. What would be the safest way to desensitize the knock sensors? (that may require a new thread, i may start one tomarrow if i dont get enough response here).

thanks again guys

Viper

iTrader: (6)

"keep in mind when in SD tuning mode, you need to modify the secondary timing table, not the primary."

I always just copied the high octane table to low octane table for tuning SD mode.

For VE changes, yes, I make changes to the secondary VE table and populate the primary.

TAQuickness

iTrader: (28)

Back to false knock.

1) How's your oil smell? If it smells strong like fuel, it shouldn't. Change it and work on getting your tune closer to stoich.

2) Are you still running the stock PCV system? If you are, and haven't all ready, intall a catch can. You can make a catch can for about 10 bucks, and you can find them on ebay for about $30.

bigshoe

iTrader: (2)

Viper, I think he meant the Low Octane timing table, and yes, i've been doing that too.

TAQuickness:
1. havent smelled my oil, but i will do that in the future
2. I upgraded to the ls6 pcv system, no other changes to the pcv system though

now if the oil smells like fuel, you would think bad piston rings right? are you saying that bad rings can cause false knock? car has 83kmiles on it, but had the same problem when it had around 30-40kmiles (when i first bought atap).

TT_Vert

iTrader: (12)

yeah sorry, i meant low octane table..

dave

TAQuickness

iTrader: (28)

If the oil smells like fuel, it doesn't 100% mean your rings are bad. In my case, I was running way too rich. I caught it before it did any damage. The fuel will thin the oil a bit, making it easer to suck in through the PCV system. Oil through the intake will cause false knock.

I was having a similar situation until I got my catch can in place. You may still consider fabbing up a home made catch can (bout $10) to see if it helps.

WS6FirebirdTA00

iTrader: (33)

i made a catch can for 8 bucks from pvc pipe at lowes and then i painted it with high heat paint, it was quite sharp looking imo

bigshoe

iTrader: (2)

catch can sounds like a good idea, I may make one of those,

thanks again, i'm about to make a post about the correct way to desensitize knock sensors

TAQuickness

iTrader: (28)

I have the home depot brand - unpainted, and looks like ***. BUT - it works and eliminated my KR.

WS6FirebirdTA00

iTrader: (33)

how much oil were you getting? enough to get visible oil in the intake? ive got the ls6 pcv conversion on mine and still get little bits of oil but the catch can never did much for me so i took it off

TAQuickness

iTrader: (28)

The oil was all the way up into my MAF. When I cracked the TB blade back, there was a standing pool behind it. On hard decell to acell, I would get a small white/blue cloud. This has a bit to do with the mod to the valve covers so the RA's would clear, and a super rich initial SD tune.

A little seafoam to clean the intake, a catch can, and wow what a difference.

jyeager

That seafoam comment got me thinking...On your other thread I mentioned the possibility of oil contamination....If so, that's not FALSE knock it's real. However, just because the oil consumption might have been licked, it's still possible that there is carbon buildup in the cylinders resulting in knock.
So before you assume it's false knock you've got 2 more things to do: 1) ensure there is no oil consumption to speak of. 2) do a top-engine clean to remove any accumulated carbon.

WS6FirebirdTA00

iTrader: (33)

what he said, i was just about to say not to desensitize anything until you know 100% its false. and by false it means somethign else tripping the sneosrs not the combustion process