With 28.5 degrees you may still get knock... I am wondering if you're running lean.
With 28.5 degrees you may still get knock... I am wondering if you're running lean.
Was the lean comment posted towards me? I guess it's possible, but I've richened the WOT tables quite a bit. Guess I could add a little more.
On the timing, the description on KR is that it will pull X amount of timing per crank revolution when KR is detected until KR is eliminated, then add X amount (smaller number) per crank revolution until it reaches the max timing possible under the high octane table, if I interpret what I read correctly. Looking at the data, there is a final timing reading (cyl 1 timing) along with the KR reading. So, the KR should be a usable tool to set the max allowable timing for the engine. It would just be a matter of knowing what the variables are that affect final timing, like in a flowchart or something, along with the weighting. With that you could tweak timing so it ran the ragged edge all the way up the RPM band, with the knock retard available for special circumstances like towing a trailer up a hill or something.
Oh well, I'm down to adding a degree of timing here, taking a run, then drawing it back where I get the KR now, so I can get something to give to Pop in the next 2 weeks. My own truck is almost done enough to start driving, might even be able to get it finished today.
Are you adjusting your VE or MAF tables inbetween the timing adds?
I was, but here on out I'm adjusting one table at a time then taking it for a run to see what happens. I've not been playing with the MAF table, mainly just the VE and spark. Thinking of adjusting the PE table to be a little richer on the next tune though. Might make it a straight 13 to 1, then see what the KR does.
I don't know if I already asked you this, but what are you burst knock settings like.
Zero all of them and then see if you still get knock.
I'll have to try that later. Question now is, why would the low octane table have higher numbers than the high octane table? I'm showing this in the left side of the screen when comparing the two tables. I've found that the O2 voltage was showing too lean in the WOT acceleration and have adjusted, but am now seeing this disparity. Should not the low octane table ALWAYS have a lower number than the high octane table for the same cell? No idea how this happened, but I've adjusted the low octane tables to lower than the high octane tables.
You sure its the stock timing?
I gave it some thought as I was driving down to my dad's house yesterday, and it was not. The stock timing map was identical for the low and high octane tables. The problem is that I never actually compared the stock low octane table (never adjusted it) with the new high octane table to make sure there were no issues. I've also got my own truck back on the road now, so I've now got less than 2 weeks to get this squared away before the truck goes back. I hate it when I make stupid mistakes like this, but I feel a lot more confident with the software now than I did.
Now that I realized my mistake here, I'm thinking of restarting the process again by putting the stock tables back in, then just adding 10 degrees across the board on the high octane table, then tweak from there.
Question - Will a wideband O2 sensor work to tune if it is hanging in the tailpipe or does it have to be up front and installed in a bung in front of the cat?
Last edited by Telco; March 18th, 2008 at 11:33 AM.
10 degrees is a LOT of timing. You won't *need* more than 3 or 4 in most places. Take small steps towards your goal and your engine will be much happier with you for it.Originally Posted by Telco
OK, examined the base factory tune that I pulled when I first got the truck in my hot little hands, and IT was showing an inversion in the table. Unreal. I know for a fact that I'm the only one outside GM that's ever messed with this computer.
dc_justin, thanks, that's what I plan to do. I'm just setting up the initial table and decided to go with an 8 degree difference between the two, not 10 like I had planned. I'm also smoothing the low octane table out some, there are fields where the difference is as much as 15 degrees. I'm feeling a lot more confident in this table over the last bunch.
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