If you guys have any NA motors out there that run good, do you mind showing what both your ignition tables look like. My car runs good now that I added a bunch of timing to it but I feel as if I have too much timing at wide open throttle and don't really want to push it. As of right now my KBT and MBT are the same. I run a set of comp cams xe268h with self ported PI heads, bbk shorty headers and a CA intake.
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MBT is gonna be the optimum timing, assume you have the octane to support it. MBT doesn't change without extensive engine changes.
Eric Brooks
HP Tuners, LLC
I have ported PI heads and a set of xe268h comp cams, would that be extensive enough to possible change the MBT table?Originally Posted by Eric@HPTuners
Not in my experience. Best thing is start with the stock MBT run it on the dyno and then you could use the global spark added to add a couple of degrees and make another run and see if it makes a noticeable difference.
Eric Brooks
HP Tuners, LLC
I'll start off by saying I'm no expert at tuning the EEC by any stretch, just a weekend warrior trying not to scatter parts, and every combo might like something a little different.
Your table looks to be stock for MBT and you don't mention a base table, so I'm assuming whatever your strategy is doesn't have one and there's nothing else clipping your final spark value. So, if you just copied MBT values over to the BKT table, and you're happy with the way it runs (and it's not pinging/knocking/detonating at any RPM/load combo), that's all that really matters. If you feel you have too much timing in it WOT, back it off a couple degrees and see how it feels. It's hard getting timing totally dialed in on the street without quantifiable results (dyno, timeslips, etc.). And, furthering Eric's point, I typically only modify MBT values if I'm scaling load (e.g. for a FI build). On basic H/C/I NA combos, I usually leave MBT alone and modify the borderline table. Regardless, EEC will deliver the lowest spark the ecu calculates at a given time based on those tables and their modifiers. I think most importantly, is the final advance you're seeing on a pull in your logs reflective of what you're commanding?
My old tune would run horrible in the 1-2k range at any load and I suspected timing as I had someone else tune it prior to me. I didn't know where to start so I just plugged in those tables I found on this forum hoping it would do something, but in the end it helped my performance a ton! But when I really start loading the engine up past 70% load I've notice it starts to detonate so that's why I started asking what people are running on modified builds. So should I change my borderline knock table back to stock and only modify the global spark adder? I haven't been able to tell if the spark that im commanding is actually being reflected, but I just found out today that I can use air load to get engine load, so I will be going home here in a bit to find out.
Last edited by Adammm57; 10-18-2024 at 04:43 PM.
Again, no expert, but I wouldn't necessarily return the borderline table back to stock if you're happy with the performance outside of where you're getting some knock. I also wouldn't ONLY modify the global adder...that's a global function and will add (or subtract) from your final spark value based on your input, not just WOT. To me the global adder has been helpful for base tuning to be able to pull out say 4* across the board while getting fuel dialed in, or like Eric said, experimenting to find MBT on the dyno. So that said, you could use the global adder to pull out 4 degrees (or some other value) GLOBALLY and see if your knock goes away, then modify the areas of the borderline table where you were getting knock accordingly, and log/iterate/log/iterate from there til you find what it likes. But again, I don't know what your modifiers look like, and logging the spark value you're actually getting (and understanding where that value is coming from), along with when it knocks will give you the most info as to where you need to make timing adjustments. Timing is a tough one on the street. I grenaded the last motor in my car with timing that was too aggressive for pump gas (2v with 20* and 19psi, made several pulls with that value til it gave). Live and learn, and now I make smaller, more conservative changes. I've tuned a couple 2v NA cam combos that liked 19-20* of total advance at WOT and another that liked 25*, and no idea if that was ideal timing or not, just where they seemed happiest
With your NA cam builds what kind of timing were you seeing around 1-2k rpm around 70%+ load? My buggest drivability issue is around that range if rpm and load. Even with all the timing i add it helps a little but seems to want more. Idk if its really my timing at that point or what but my afr seems to be good and i really dont know when to add more timinf in honesty, i only know when to really take it away when I start hearing pinging.
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