I dropped a 383 into my '90 Corvette, which someone was helping me tune. Due to a series of problems continually throwing the tune off, he threw in the towel, so I'm going to finish the tune on my own. I've done a lot of research, and I'm a quick learner, so I think I understand the concepts pretty well. However, knowing how much a mistake can cost me, I want to make sure I have everything straight. Here are the steps as I understand them:
- Datalog, adjust VE table values, and repeat until BLMs are all within a point or two of 128.
- Set deceleration fuel cutoff
- Slowly bump up Closed TPS Spark Advance values in each cell until datalogs show knock retard there, then decrease it a point or two in that cell; find max for each cell
- Repeat process for part throttle (Main Spark Advance table up to 90 kPa)
- After making sure BLMs are correct and there is no knock retard for other circumstances, set advance for WOT
Notes:
- WOT AFR should be richer, cruise AFR leaner
- All tables (whether in the BIN or datalog) should show consistent trends, not sudden spikes
- Too much advance can decrease power before getting to the point knock is seen
- Datalogging to set main VE and spark advance tables needs to be done in closed loop
Questions:
- If a datalog doesn't have a value for a BLM cell, I just extrapolate the VE from adjacent values?
- When do I set open loop change to AFR vs coolant temp and MAP? Once I'm done with everything else?
- My VE is pretty much maxed from 3200-3600 RPM at WOT, so the guy helping me suggested changing injector flowrate to compensate. But from what I've read, a VE that high on gen 1 SBC is pretty abnormal--you guys think there's a problem there?
- I read PE mode must be disabled to get BLMs at WOT since PE puts it into open loop; however, my datalogs show BLM values for WOT. Why the discrepancy?
- How many spark advance cells should I change at a time?
- Are there any other tables/scalars/flags I need to adjust?
As an aside, how the heck do you add line returns in a post? I've tried 3 different browsers, I've tried multiple returns in a row, I've tried BBCode... everything I try ends in line returns being replaced with spaces! The only way to get around it was to take advantage of lists' inherent formatting.
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