Base Spark vs. Hi / Lo Octane Spark tables.
10-21-2005, 02:19 PM
#1
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Base Spark vs. Hi / Lo Octane Spark tables. Should the Base spark tables in park/in gear match the High octane or Low octane spark tables? I have read some info saying they should mirror one another. But I noticed, with the stock configuration, base spark is lower.
Anyone know why this is ?
Relating mostly to Idle region here....
Anyone know why this is ?
Relating mostly to Idle region here....
10-21-2005, 03:06 PM
#2
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Yeah I would get them close so the transition between the two tables isnt that drastic. Base spark tables are used when the TB is closed and the HO/LO take over for any other conditions.
10-21-2005, 03:38 PM
#3
It is not neccessary. Vehicles are really driven to 5% TPS from a dead stop, so GM didn't really care to make them match. Plus you will not notice a timing difference from one to the other ... the difference will come from the increased airflow when to open the throttle body blade (typically around 12%-18% TPS for normal driving). Also, if you notice, you can set when the ECM stops looking at the Base Timing table and starts looking solely on the LO/HO Timing tables ... it is around 1.5% TPS. Mearly touching the throttle enables the LO/HO tables as per OEM.
10-21-2005, 04:26 PM
#4
I respectfully disagree with Flame Throwing SS. I believe that having all 4 tables matching in the idle areas is critical for superb street manners when running a big cam. First of all, a cam with lots of overlap needs more timing to keep it from running like a turd. Next, you want your timing to match when you're cruising at low rpm. Going from 5% TPS to 0% TPS back to 5% should not make lots of timing changes. If it does, you'll get lots of shaking and bucking. I don't like that. Matching all 4 tables goes a long way to curing the bucking blues.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
10-21-2005, 05:16 PM
#5
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For an all out race car it may not matter that much but for the guy looking for every ounce of driveablity it makes all the difference. Like Patrick said you want the tables to be close or match this way when there are transitions between these tables the pcm is seamless about switching back and forth. 