![]() |
@thambu19 I just sent you a B01C def because you posted a pic with that CAL ID. I just figured that was what you had.
|
Quote:
I am itching to try out some PFI/DI cal changes and E85. The Takeda Intake has arrived and I want to install that as well with the right MAF scaling. I love the intake honk from 4K onwards but pretty sure I can make it happen even earlier by changing the AVCS. But that is pretty much what OFT OTS cal does too. They moved the Exh timing creating more overlap and this should make more intake noise :) although their reason for doing it was for more torque and less torque dip @KoolBRZ Thanks a ton mate. Got a chance to try out 100% DI? I don't know why the OEM did not calibrate for full DI at low speed WOT. Defeats all my engine knowledge. I can only think of emissions as a likely reason for staying with 50% PFI DI split. |
|
Blast you @thambu19! Your idea worked.
I loaded a tune with your suggested revisions first, and didn't even load any of mine to compare. It was so much better! @!#*&% you! I made 4 other tunes to try out, and now they are all worthless! Blast you and your intelligent mind! Now I'm going to have to rethink these principles you based your revisions on so I can find how far the limits are so I can push it to the limit.
|
Quote:
Sent from my HTC One_M8 using Tapatalk |
If yourintent is best engine response and can sacrifice fuel economy there are other cool things we can do with cams at lower loads. Maybe better for a sports mode calibration if we can switch between the two at some stage. I'd calibrate the cams completely differently if I want performance instead of mileage
Sent from my HTC One_M8 using Tapatalk |
Quote:
|
OK here goes my latest
1 Attachment(s)
Here's my latest attempts to understand and push the limits of the @thambu19 principle. I'm going to try out these four shown.
|
Reasons for chosen DI/PFI ratios
Quote:
1. Going DI at low speed knock limited regions will increase volumetric efficiency and improve knock resistance 2. But going DI will make combustion slower so need to add more spark 3. The lower the speed the sooner the transition from PFI to DI because of same reason above. 4. Use PFI at loads that are not knock limited to improve fuel mixing and take advantage of faster combustion of PFI. This should reduce combustion variance and make engine feel more stable (less stumble) 5. Make sure to use 100% DI at the torque dip region 6. If it was upto me I would have tried 100% PFI at Idle. I think Toyota went for DI there for emission gains and to avoid knock during HOT RESTART. With PFI they need to model puddle dynamics when the engine is cold and other stuff. With DI they get better fuel control. I dont know if they are even going slightly lean at Idle for fuel economy reasons. 7. Going 100% PFI should also reduce the chirping??? I dont know for sure but worth a try. To really reduce chirping the fuel pressure must be dropped for DI at idle and then going 100% PFI. This is because even if DI isnt being used the pump is still working to maintain fuel pressure. Currently 24bar or 2.4mPa fuel pressure is commanded by the DI system at idle raising to 200bar pressure at WOT. |
1 Attachment(s)
OEMs usually play the emissions game rather seriously. Like VERY SERIOUSLY. For example look at this stock map. They went from 50% PFI to 100% DI at 2400rpm because that is where Scavenging peaks in this engine. So that is where going PFI will make the fuel short circuit engine and go directly to exhaust causing HC emissions. So by going DI it allows them to scavenge harder. Upto 1-2% O2 in the exhaust is manageable by the CAT. Anything over that the CAT cannot keep up.
|
If you look at this posting by @Shiv@Openflash
http://www.ft86club.com/forums/showp...73&postcount=1 you will see the two distinct peaks on either side of the torque dip. I have a strong suspicion that is it because of the unequal length header working. Equal length headers both tune at the same engine speed but unequal length headers should tune at two different engine speed. The side with shorter tube will tune at higher engine speed (4500rpm?) and the long one tunes at lower speeds (2400rpm?) What he had done is create more overlap by moving the exhaust closer to intake or retarding the exhaust timing and maybe increasing intake advance and this maximises scavenging at the cost of HC emissions and possibly intake noise. The loud HONK you hear when the engine hits 4K rpm is due to this effect where intake valve is opened so early that combustion gases gush into it at the same time they are escaping through the exhaust. The more the overlap, the louder the noise and OEMs limit the NVH beyond a point. We love the HONK so we can do what we want with the timings :) |
Quote:
|
@thambu19 how much PI is needed and where load rpm wise to maintain intake valve cleaning properties ?
another question, if you have a look at the intake cam tables at low load rpm they do a weird dance go from zero then negitive then back to zero then increase above zero. I have assumed the negitive dance was emmissions related ? |
Quote:
|
Quote:
PFI at extremely low PWs (pulsewidths) wont really help clean the valve (like idle) because the injection duration is so short the gas fully atomizes rather quickly. What is really needed for clean up is substantial PW. I cannot tell how much PW in ms exactly because I do not know to be honest. These engine will start seeing knock at 40-50% load at speeds between 1000 and 3000rpm and higher loads at higher engine speeds so increasing the PFI% below that is always going to help valve cleaning. Regarding the Intake cam timing I will need to make some wild assumptions shall I? 1. Generally 1200rpm to 2500rpm is the region this car would run in an FTP cylcle (one of the fuel economy test cycles) 2. Toyota wanted to go to LATE Exhaust Opening as soon as they could. So you will see Exh timing go to 40 as soon as they can. They cannot go to 40 too early in load because if they do they deteriorate the blow down of exh gases causing combustion quality issues. The reason for going late Exh opening/closing or retarded timing is for Fuel economy to get maximum expansion of the gases in cylinder. 3. With Exhaust timing so retarded the intake cannot be advanced beyond a point. If advanced it will cause the exhaust to be pushed into intake manifold during the exhaust stroke and rebreathed during intake stroke and this will increase incylinder residuals causing combustion quality issue. So by going Late Intake opening/Closing (-10) they are using a late/late strategy. Meaning open Exh late and intake Late. 4. By moving the intake late they are reducing the Dynamic Compression Ratio of the engine and this helps in reducing pumping losses (something like drag) and also helps in reducing knock. So overall this would have been a move to maximise fuel economy. Once engine load is at 0.7 the intake is being moved to a more advanced position because 1. The throttle has maxed out in authority or in other words the throttle is almost fully open and the MAP is already 90kPa or above and the only way to get more air to flow is to change cam timing (throttle is maxed out) 2. At this time scavenging kicks in and moving intake to more advanced position helps with scavenging 3. They can simply tolerate more internal residuals at these higher loads |
Your table is still the best, @thambu19.
1 Attachment(s)
Here are 3 more attempts to improve on @thambu19's table. His Total Injection PI to DI ratio table is so smooth. There is only a slight delay transitioning to full DI, and I think timing advance could fix that. The question I want to answer with these attempts is really "How much is too much?".
|
@KoolBRZ you definitely need to adjust the timing where we have increased DI % from stock cal
Everytime you flash are you making sure to relearn the background noise of the knock sensor by doing a partial load sweep from low to high engine speed? Normally you start at 2K rpm low load and slowly let rpm build until 6K to 7K (not WOT). This helps ECU learn background noise caused by valvetrain and other components. Helps ECU call knock more accurately and overall a consistent knock detection instead of too early or too late. My only concern with flashing is ECU loses the chain stretch information. This is usually accounted for because when the company flashes a cal at the plant the engine will learn the relationship between crank and cam and then on wards it will use this relationship to estimate how much the chain has stretched. For example initially when the chain stretches a lot when new the cams can get more and more delayed in actuation or cams can get retarded. Some OEMs can use the chain stretch info to position the cam after discounting the stretch. What I mean is physically the Intake cam could have moved to 42deg instead of 40deg retard. What Ecu can do is move the Cam to 2deg more advance thereby engine is actually getting the needed 40deg instead of 42deg. |
I'm subbed to this thread, and it's a very interesting discussion, but I have a question for the modders.
What is your ultimate goal with the changes you are making? - Increased power for the track? - Better driveability (i.e. smoother acceleration, reduced knock, etc) ? - Improved mileage? |
Quote:
Drivability and fuel economy is always a trade off because: 1. For FE you move the cams in such a way as to increase MAP as soon as possible and achieve de-throttling this kills driveability 2. If one wants pure driveability, id move the cam timing more towards WOT cam timing earlier in the load. I mean blend the cams towards WOT cam timing not just pop into WOT cams timing. Then Id increase spark at the lower loads to slightly oversparked by a degree or so (non knock limited region). This will improve combustion stabilty at the cost of some FE. So yea to answer the question we are trying to understand the engine better that way each person can tune it to his/her liking. Some guys are all about FE and we can do that and some are all about performance (like me) and we can do that too. |
I want drive-ability and power, and I want it smooth with no flat spots. I want smooth economy up to .7 load, and acceleration from .7 to 1.0 load, then sheer power from 1.0 to ~3.0 load. Yes, I am slightly super-charged with the Phantom ESC, and that's how I can get to 3.0 load. That change thambu19 made to the PI to DI ratio table has made more of a difference to open-loop acceleration than any other improvement I have made so far. Closed loop is pretty good too. Since I am super-charged I can't boost my timing by too much, since I am already using Shiv's Phantom ESC tune's timing tables. If I'm having a hard time improving on his table, that's my way of showing respect for his work. I'll always keep trying though.
P.S. @thambu19 can you please get an OFT? There are always a few for sale in the member classifieds. OFT users need your input. I can also send you a tune with my revised AVCS tables, and you can show me where I went wrong. PP.S. Do I make timing advances to Base timing A, B, or some other table? |
Quote:
edit: base timing A is for emergency mode, I believe PS: thread has been turned to awesome overnight (at least in my timezone ;)) |
Quote:
The vast majority of the time is spent on Base timing B. |
Quote:
Their is rearly no difference between using oft or tactrix other than ease of use if were just talking flashing rom is same. Oft has far easier to use logging and real time display, tuning alerts ect. which tqctrix does not. |
Quote:
I forgot you were on the Phanton ESC. If you are boosted even slightly the gains you will see from 100% DI will be far more than those with NA will see because earlier with 50% PFI you were probably just short circuiting fuel into the exhaust for no reason. Short circuiting fuel is also bad for exh and CAT because the fuel dumped will burn up there causing heat and stress. But by going DI you may now see some lean-ness in the exhaust being picked up by the O2 sensor but that is okay. Regarding AVCS or timing it is an altogether different topic and we should start a timing discussion like this PFI/DI. In short though with even a slight boost your timing should be slightly (2-5 deg) more advanced (open and close earlier) than stock timing depending on how much boost you are running. With a lot of boost it will be more advanced. I can explain why in another timing thread. |
Quote:
Are the negative values real? I mean does the the cam actually go there? I thought the rage of authority was only from 0-40deg for intake. In that case the negative values could be a strategy to force the cams to go to their end-stop or lock-pin positions where Duty cycle = 0. Next time you log data in that area can you check if the DC goes to 0 at this region? This will be a strategy to learn end-stop location so that the ECU can learn the shift in position if any due to tolerance limitations part to part or even chain stretch when it happens on a newer engine. I see that exhaust does not use it. Not sure why not. |
Quote:
Regarding AVCS tuning, go for this thread: http://www.ft86club.com/forums/showt...highlight=AVCS |
Quote:
How would you like to contribute to a new thread, "PI to DI ratios and AVCS timing", since they do interact and affect each other? I think you should start the thread, based on the knowledge and experience you have. |
Quote:
Would value your input on the differences between supercharger and turbo theory for AVCS. |
What that PI table was actually doing
1 Attachment(s)
It occurred to me that @thambu19 made his table before he had the means to edit the thresholds, so I created a table with the cells below .35 zero'd out, because the thresholds would have forced them to be treated as 0%. I'll be trying that one and several others tomorrow. So far only the tables very close to being identical with @thambu19's table have even come close. The tune with his table seems somehow unfinished, to drive just a bit off. So I've been trying to add or change it a little bit at a time to polish it and make it better. With an AT it's easy to know when a tune is right. The transmission shifts smoothly, with no hesitation, it accelerates easily, and just seems to coast when I let off the throttle.
|
Quote:
The table values get interpolated and the thresholds are applied to the interpolated values, not the table values. So: a transition from 40% to 30% will be slightly more gentle till it hits 35% and gets cut than a transition from 40% to 0% will be. |
@KoolBRZ
Keep in mind that the shifting of an AT has many more parameters that affect it one of those being the torque model accuracy. The transmissions controller gets the torque (modeled) from the engine controller and uses the number to determine the clutch/band engagement and disengagement time to make sure there is not drag on the off going element etc which can cause hesitation. Imagine this like a DCT transmissions where both clutches are engaged at the same time wearing out both clutches and bogging down the engine during the shift. In normal case the modeled torque goes up as the estimated airflow goes up (via supercharging). So with the AT it could be a zillion things that are making the perceived shift feel better. I am going to be away for a week (vacation in Puerto Rico) so hope you guys would have perfected the DI/PFI by then. Reg AVCS lets not start a new one. Let us use either @Kodename47 or @ztan thread and have those discussion going there. Yes the AVCS for turbo will be different from SC. The WOT timing for NA would be perfect on the OTS maps no doubt about that. There is probably more on the table at part throttle to improve drive feel but that will come at the cost of FE so not many will want to do that. |
We have been discussing here a lot and still dont know anyone personally. Need a thread to get to know each other better. A personal touch or connection can go a long way
Sent from my HTC One_M8 using Tapatalk |
Enjoy your trip, soak up all the warmth you can, because...
Quote:
|
Humble people... I love this thread!
Sent using tapatalk |
Quote:
Sent from my HTC One_M8 using Tapatalk |
Yes, but there is a big difference between wanting something somehow better, and not knowing how or why, and knowing why, visualizing what should be, and finding out how. BTW, I think we need another map for cold while using your map for warm/hot.
|
Quote:
http://www.ft86club.com/forums/showp...&postcount=112 |
Quote:
Sent from my HTC One_M8 using Tapatalk |
Fantastic! lol
Edit: Thanks Happy Turkey day! |
Hey, I've tried to tweak it a little
Quote:
|
| All times are GMT -4. The time now is 08:55 AM. |
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2026, vBulletin Solutions Inc.
User Alert System provided by
Advanced User Tagging v3.3.0 (Lite) -
vBulletin Mods & Addons Copyright © 2026 DragonByte Technologies Ltd.