Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

Knock?

Old Jan 2, 2003 | 11:02 PM
  #1  
lt4 fd's Avatar
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From: plano texas
Knock?

I just got datamaster working and noticed that sometimes when I floor it the advance jumps down to like 14 degrees or really low like that and normally its like 30-40 or something. You can see it dip down on the graph too, I also have the lt4 knock module so its probably not false. Also it says my coolant is about 90 degrees celcius which is hot for a 160 thermostat no? 90 degrees celcius is 194 degrees farenheit, correct me if Im wrong. Well thats all Ive noticed so far Ill keep looking at it. Also I havent checked it out totally yet but what ever knock count is it said 5163 in about a 15-20 minute normal drive which doesnt sound good.
Old Jan 3, 2003 | 12:48 AM
  #2  
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From: so close I can taste it...
What gear are you "flooring it" in?
Also, you might still see engine temp get that high. Depends on when the fans turn on too...not just the thermostat.
Knock count tells the engine when to pull timing out. Not sure, but I think it works like this: knock sensor tells the computer that it hears noise and if the computer gets too many counts in a certain peroid of time it will retard timing. I wouldn't be too concerned with knock count, just retard.
BTW, go to Setup then to Display Units and you can change from celsius to farenheit...if you haven't already.
Old Jan 3, 2003 | 11:55 AM
  #3  
lt4 fd's Avatar
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yeah I just changed everything to farenheit and I looked at retard adn there was none so WOOHOO! Also my fan relay is broken so the fans dont come on or atleast the engine doesnt stop heating up till about 235 or 240 if I let it idle without the ac on, ac turns on a secondary fan. It drives at 190 normally hmph. Well anyways Im still trying to figure out everything I can do with this and hopefully getting tuner cat very soon so I can change stuff. This is one of the coolest things Ive seen in a while
Old Jan 3, 2003 | 01:45 PM
  #4  
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From: Hell was full so they sent me to NJ
The timing is set from a table, and the table has rpm on one axis and MAP on the other. When you "floor it", you open up the throttle, and MAP approaches atmospheric pressure, or 90-100kPa. At 1,400rpm for example, the stock timing table would move the advance from 40deg at 30kPa to 14deg at 95kPa.

There is a sample timing table in the LT1_Edit instruction page, and I have a partial copy of one in my scanner writeup:

SCANNER DATA

When looking at scan data, the value you see for spark timing advance will be the value from the table, minus the value the scanner is showing for knock retard.
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