Forgive me since I"m new...but I'm sure you'll be seeing me ask alot of ?s on this board in the next few weeks as I try to learn about chip burning. I have posted on here before, but never anything in depth...hopefully that will change...

The question I had was trying to understand the knock attack rate and knock recovery rate tables on my 89 bin file.

1) The recovery rates...I got a bin from a friend of mine and was perusing it...he had the % recovery rates over 100%(up to 200%) at the higher rpm values...this basically disables the knock sensor, right? That is my theory anyway.

2) THe attack rate is in deg/ms...well, my 89 auto bin file has pretty high attack rates...up to .41 deg/ms...the highest I have seen anywhere else is .36 at the higher rpms..whereas my 305 is 400-.25;1200-.41;2000-.41;3200-.36;4800-.25
This sounds high to me, but since I'm new I want to leave these high that way if I screw up and put too much advance in it will pull the knock quickly...right?

I hope I wrote this so you guys can understand, if not, ask and I will try to clarify.

Thanks,
GregF
87 IROC
http://www.geocities.com/gsfranks

[This message has been edited by gsf-87IROC (edited March 16, 2001).]

 

The GM K/S is acoustic. First and formost.

using acoustics to detect detonation is just a COST EFFECTIVE way of finding detonation in a limited band. Sooo the strategy seems to be any right sound trips the ECm into retarding the timing, and then just keeping the timing retarded enough so that for a while the engine is protected. Depending on your level of skills in tuning you can play with the rates. *generally* you want the decay rate to be less, since your reading plugs, and closely lookiing at what your doing. In some applications having a real high attack and decay rate can mean alot (most notibly the syclones).
If you not good at reading plugs for detonation is far better to leave it alone.

The stock cal has a certain amount of hysteris in it, so while 4d of retard is what the engine is seeing the ecm will go to 6d to assure no damage, er min damage.

 

Hmmm, so when you say you want the decay rate to be less...you mean I should have the tables set to put very little of the timing back in so that I can get the plugs read before the 'story' of what was going on disappears...right?

I left the tables alone since I am a very new guy...

Thanks,
Greg

 

Once your familiar with what is working prom wise / performance wise you might try changing the decay rate, meaning reducing the time for timing to recover to normal, ie change it to like 250% to maybe as high as 400 (think that is the max), but for this to be really effect means being really close with everthing else first.

You normally don't need to change alot to get a reall nice chip, the trick is changing the right thing enough to get the engine happy. It's easy to fall into just add timing and fuel. Lots of times you need to lessen the fuel in some spots, and when right with some cars can run alot less timing for X amount of performance. Like in my turbo car at WOT I just run 18d total timing, on my 355 28d.

 

The 200% recovery rate doesn't disable the knock sensor (trust me, it's still working fine and pulling out timing in 3rd gear due to a driveline vibration). It adds back the amount of timing pulled out at a rate of 200% per second. So, if you have 4 degrees pulled out, it'll add it back in 1/2 second. At 100%/second, it'll give you back those 4 degrees in 1 second. Since I'm running the stock timing table still and only run 92-93 octane gas, I'm getting no knock throughout 1st and 2nd gears (except a brief but small spike after the 1/2 shift).

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Greg Westphal
'87 IROC 305TPI/A4

 

Wish they had one of those little smiley faces with a lightbulb over it...I was reading the last 2 posts and whammo!! I figured out what the heck was going on...SWEET!!!! Thanks for the info guys...

GregF
87 IROC

 

gsf-87IROC, where did you find that table? Im using tunercat and that table wasnt there for the 6E tdf file. If you are using tunercat Id assume that you have sucessfully used the tdf editor. If so how did you do that!? I cant figure that out for the life of me. As far as I understand there are a lot of tables that are in the prom that I cannot see because the tdf file that I have is not configured for them. Is there somewhere that you can direct me to find info on how to do this for the 6E tdf?
Thanks


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355 10:1 , AFR 190 heads, LT4 HOT cam w/ 1.6 roller rockers, complete Superram intake, 58mm BBK TB, 24# injectors, screens out of MAF, MAT relocated, March underdrive pulleys, Streetdampner, Crane HI-6 ignition, 160 thermostat, K&Ns, TES headers(Jet hot coated), Mufflex 4' cat back, B&M shift Kit, 2500 converter, and 3.27s.

 

I emailed Tunercat one day after checking their website and seeing that my 6e file was about 4 revs behind where they are now...so I asked them to send me the new one...rev 'L' I think...then something was said on another mailling list about these attack rates and I asked the guys at TC if they could update and add them...even though I had no idea where the table was...the next day a new copy was in my inbox. If you have a licensed/purchased version of tunercat...I'd just email and ask...




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GregF
87 IROC