Spark Advance Primer Needed
Spark Advance Primer Needed Just a few questions re spark advance
1. Atap captures a range of values of [-64, +64]
According to atap, Neg values are BTDC, positive vals are ATAC
Would that make neg vals advanced and pos retarded, or is advance and retard relative to some base positive value?
Does
2. I read that WOT Spark Advance s/b in the 27-31 range.
Is there a normal range for nonWOT conditions?
Is nonWOT worth logging?
3. Is it useful comparing Spark Advance to other parameters, RPM or FTC for instance.
Just trying to get a handle on this stuff <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />
TIA,
Scott
<small>[ April 17, 2003, 07:59 AM: Message edited by: 2002ScottOnyxSS ]</small>
1. Atap captures a range of values of [-64, +64]
According to atap, Neg values are BTDC, positive vals are ATAC
Would that make neg vals advanced and pos retarded, or is advance and retard relative to some base positive value?
Does
2. I read that WOT Spark Advance s/b in the 27-31 range.
Is there a normal range for nonWOT conditions?
Is nonWOT worth logging?
3. Is it useful comparing Spark Advance to other parameters, RPM or FTC for instance.
Just trying to get a handle on this stuff <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />
TIA,
Scott
<small>[ April 17, 2003, 07:59 AM: Message edited by: 2002ScottOnyxSS ]</small>
TECH Addict
Joined: Jul 2002
Posts: 2,261
Likes: 0
Re: Spark Advance Primer Needed Ok I'll try to help some. You want Max Combustion pressures to build up around 11-13 * ATDC. In general it takes a given amount of time for spark production and propagation.Then we need time for the combustion to develope appreciable pressures.The faster the RPM the greater the advance of the spark so that the events occur at the optimal time. If the spark wasn't advanced it would arrive too late in the cycle and combustion pressures/forces would occur( after the 11-13* ATDC)too late. So advanced is farther before top dead center or whatever your base timing is. Retard is less of course.AsAdvance is related to RPM you would want to log this. Hope this helps. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" /> Maybe some of the Gurus can chime in.
Re: Spark Advance Primer Needed 1) Ignore Atap help, it sucks, is confusing, and is often wrong. For your application, (unless you have LS1 edit) should always see timing values in the range of -4 to +41. If you see timing outside of these boundries, then you have issues. Positive values indicate an ignition point prior to the piston reaching top dead center. Negative values indicate an ignition point after the piston has reached top dead center.
2) When it comes to spark advance the numbers that you should be interested in are those at WOT. Part-throttle spark advance should only be looked at if you are having problems with detonation or start tuning.
Normal WOT advance for a stock 2002 car is probably going to land you in the mid 20's. It depends on how much air your car moves.
3) It is very useful to log spark advance along with MAF flow, RPM, KR (knock retard), and Inlet Air Temp (IAT). Once you get into tuning you will use these perameters to make adjustments to your timing tables.
Watch your timing in realation to KR. This will give an idea of how much ignition advance your setup can take at certain atmospheric conditions and will help with tuning. If you start to see KR, then you know that your timing is too high (or you have false KR).
Good Luck,
Kevin
2) When it comes to spark advance the numbers that you should be interested in are those at WOT. Part-throttle spark advance should only be looked at if you are having problems with detonation or start tuning.
Normal WOT advance for a stock 2002 car is probably going to land you in the mid 20's. It depends on how much air your car moves.
3) It is very useful to log spark advance along with MAF flow, RPM, KR (knock retard), and Inlet Air Temp (IAT). Once you get into tuning you will use these perameters to make adjustments to your timing tables.
Watch your timing in realation to KR. This will give an idea of how much ignition advance your setup can take at certain atmospheric conditions and will help with tuning. If you start to see KR, then you know that your timing is too high (or you have false KR).
Good Luck,
Kevin
TECH Addict
Joined: Jul 2002
Posts: 2,261
Likes: 0
Re: Spark Advance Primer Needed </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Maybe some of the Gurus can chime in.
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"><img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> And NoGo "THE MAN" does. Thanks! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"><img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> And NoGo "THE MAN" does. Thanks! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
TECH Resident
iTrader: (3)
Joined: Nov 2001
Posts: 979
Likes: 0
From: Richmond, VA Where fast cars, well......are hard to come by.
Re: Spark Advance Primer Needed So is it safe to say that at all points on the timing tables you want the max value before the knock sensors start talking? Including the part throttle areas? Would it be possible to go too far?
