Guys,
I have the SD setup working great in the car right now. I went back and read the VE progamming thread by Tim, that is great, i understand alot now!
But i have one question. Do you worry about the spark table? Or do you just go with it from where it is? I mean, is it possible to have too little spark?

Brendan

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1987 IROC-Z L98,SuperRam,EB 6085's,LPE 219/219 Roller, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, MSD 6AL, MSD Blaster 3, Aluminum DS, 94 Disk Rear, Adjustable Valve, Precision 3.73 Gears, Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

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Spark is the FUN table IMO. Generally speaking, more spark advance gives more TQP/HP until you either hit the point of diminishing returns or encounter knock, whether audible or inaudible.

If you can make the same TQ/HP with less advance...do it. It is easier on the engine.

But there really are two facets to tuning for spark (much like fuel/VE tables) part throttle and WOT throttle. Also, if you are using an EGR you can run higher spark advances at part throttle due to the dilution of the air/fuel mixture with the exhaust gas. This is the reason I can run a high Air/Fuel ratio and a long spark advance for Highway Mode.

There is a lot of information that I don't have time to explain at this time. But hopefully, this thread may get a few responses that will fill in some of the points.

 

Oh, I almost forgot. When you increase the spark duration, you cause the mixture to lean out; which will affect your VE tables.

[This message has been edited by Glenn91L98GTA (edited May 08, 2001).]

 

Ok, so basically i should get the VE tables down to where they look the best or as close as i want them(around 125-130). And then mess with the timing?

 

Get your VE close but don't bother trying to get it exact because the VE values will change (but not a lot) when you modify the spark table.

Generally, people are adding spark so error on the side of running a bit rich. The additional spark will lean it. But remember you have two disticnt parts to tune, part throttle and WOT throttle.

The WOT throttle involves a fair amount of testing as you will end up fine tuning both your spark (the main tables and PE) along with the fuel. Also, controlling knock retard will be an important thing to be aware of. Often, increasing spark introduces knock retard, such that you may add a few degrees of advance but loose it all (plus more) to knock retard.

Also, now that you have SD, you also can run into the Low Octane Routine which yanks spark away from you without you knowing or being able to recover it. I wrote a P730 article on it. Do a search on "Low Octane" and look for the P730 article.