solidxsnake Posted March 15, 2018 Share Posted March 15, 2018 Intake temps were around 41F. Yeah, that will likel lower your boost targets. I think stock temp ranges start to apply negative compensation under 60°F or so. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 15, 2018 Author Share Posted March 15, 2018 Tadaaaaa Link to comment Share on other sites More sharing options...
solidxsnake Posted March 15, 2018 Share Posted March 15, 2018 Tadaaaaa Starts under 68°F. I was pretty close Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 15, 2018 Author Share Posted March 15, 2018 Yep. So, what would you do if you were me? Looks like what I'll do for now is modify that compensation table and put 0 there for these lower temps and see what happens. Link to comment Share on other sites More sharing options...
solidxsnake Posted March 15, 2018 Share Posted March 15, 2018 Yep. So, what would you do if you were me? Looks like what I'll do for now is modify that compensation table and put 0 there for these lower temps and see what happens. I would raise the initial/max WGDC (since it's not already at 90-100%) instead of touching the compensation table. Also, you should keep in mind, for the most part, the "Initial Wastegate Duty" table is the primary boost control table (yes, even over the Boost Targets table). The ECU first consults the initial WGDC table and uses the number there (with compensations) to set the wastegate duty. It then measures boost and compares it to target, and applies turbo dynamics to adjust WGDC to hit the target. If the initial WGDC table is set close, then it shouldn't need to apply much for turbo dynamics to hit the target. Since the conditions change quickly, it's important to get the initial WGDC table fine-tuned to always land very close to target boost without having to involve a lot of turbo dynamics to correct for it, at least that's my understanding. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 16, 2018 Author Share Posted March 16, 2018 I still did it . Changed the compensation for 32F+ to zero. We did like a 5 hr drive today. And it looks like I was able to reach target boost more often this time. I did notice a couple of overboost event (but barely 0.5 psi over or so---in 5th gear). Now, there are still situations where I am still not reaching target boost. I will provide a screenshot of a log shortly. And yeah, I also understood from that romraider post I quoted earlier in the thread, that it is better to have your initial WGDC dialed in to begin with. Another question about this 'relative' compensation value. How do you interpret it? In the equation I quoted before, I understand it should be a number between 0 and 1. But in the table, it is a value in %. I am guessing that a value of 0% in the table means 1. So if I see a value of -5%, does that translate to .95? Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 16, 2018 Author Share Posted March 16, 2018 Here is the relevant stuff from a quick log I made. I tried my best to keep the throttle position fixed and get the rpm to increase. This way, we can kinna select the corresponding TP column in the WGDC tables to compare. You'll see that I was underboosting the whole time. But at least, it appears that the WGDC reached the Max values from the table. So, if I want to revert the compensation table values as they were before, I would have to seriously crank the WGDC values if I really want to reach my target boost values. http://legacygt.com/forums/attachment.php?attachmentid=263051&d=1521089035BtSsm_20180315_203250.csv Link to comment Share on other sites More sharing options...
solidxsnake Posted March 16, 2018 Share Posted March 16, 2018 Another question about this 'relative' compensation value. How do you interpret it? In the equation I quoted before, I understand it should be a number between 0 and 1. But in the table, it is a value in %. I am guessing that a value of 0% in the table means 1. So if I see a value of -5%, does that translate to .95? Yes, that's correct. Here is the relevant stuff from a quick log I made. I tried my best to keep the throttle position fixed and get the rpm to increase. This way, we can kinna select the corresponding TP column in the WGDC tables to compare. You'll see that I was underboosting the whole time. But at least, it appears that the WGDC reached the Max values from the table. So, if I want to revert the compensation table values as they were before, I would have to seriously crank the WGDC values if I really want to reach my target boost values. That's correct. The underboosting was because you simply need more WGDC to reach the boost target. The question becomes whether or not it's safe to run that level of boost, but that's the fun of tuning! Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 16, 2018 Author Share Posted March 16, 2018 I admit I am enjoying this. I think it is pretty neat that the WGDC and boost target tables are a function on TP and RPM. This way, one can generate several logs, all done at different fairly fixed TP with increasing RPM. This could help fine tune the WGDC tables. I think I will do that. So, let us suppose I will in the end achieve target boost everywhere. But now she is knocking here and there. Next step? Simply adjust the timing table accordingly? But if I do, do I loose power? Cause you know, I want power Is it possible to maintain timing and adjust some other table in order to avoid knock? One more question: say at a given TP and RPM, I am achieving boost target given X amount of timing. Is it possible to reach that same amount of boost at the same TP and RPM but with a different amount of timing? Side note: I am realizing that the timing table is also a function of load. But load is not part of the boost target/WGDC tables.. Link to comment Share on other sites More sharing options...
solidxsnake Posted March 16, 2018 Share Posted March 16, 2018 I think now you're just getting into tuning in general: http://www.romraider.com/RomRaider/TuningForPower Remember, the tables are just numbers. Fundamentally, you're trying to balance boost (the amount of energy pumped into the cylinders in the form of air/fuel mixture) with how much timing you can run (how much energy you extract from the AF mixture from combustion) before you start getting knock (how much energy is wasted due to poorly-timed combustion). Everything is closely coupled. Running more boost (i.e. more energy) generally means that intake charge temps get higher, which will either cause knocking in itself, or require you to pull timing to compensate. So even though you're pumping more energy in, you might not be able to extract the extra because you can't run enough timing to combust the mixture at the sweet spot of the power stroke, or because the mixture combusts uncontrollably, losing power and potentially causing damage. All the tables in the ROM are just ways to play with the various mechanics that control how efficiently the combustion process is, and there's multiple ways to skin that cat. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 16, 2018 Author Share Posted March 16, 2018 Yeah. Essentially will have to play the game in balancing timing, fuel delivery, and boost. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted March 16, 2018 Author Share Posted March 16, 2018 I really thought 'RING RING RING RING RING' but no. I am really surprised. Link to comment Share on other sites More sharing options...
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