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PITA transient issue on throttle hits 4 rotor haltech elite "load rate / load accel"?
Just got this car dialed back in on the dyno after fixing intake runner leaks. Thing is making bang on power now, maxing out 4x ID1000 and 4x 2000, on a 75psi base at 13psi boost lol. Dialed in nice and clean on e85 with a dead even 11.0afr with 11.0 target.
Going into boost the target is a 12.5 at 0psi, linearized up to 11.0afr at 7psi+ Boost comes online around 4k rpm with a little positive pressure and then i have it deliberately ramp in slowly up to 9k rpm so as not to disturb the tires and keep the curve real smooth and high ended. Load method is alpha-n + boost comp which is working beautifully on cruise and in boost. No hiccups and bang on target everywhere EXCEPT TRANSIENT So, here's the problem that keeps happening, and its the same shit people are writing about on haltech forums. Haltech in fact admits to overcomplicating the fuck out of the transient settings and is allegedly rewriting all of the transient software. But in the mean its time to wrestle this beast, NO MATTER WHAT I DO TO: Rate table, sync, and async, fuel setttings, no matter how aggressive or mild, it always winds up like this: 1. rolling along nice and smooth, tip in (doesn't matter if its 20% per second or 1000% per second), you get a subsequent lean spike between 14 to 17afr. On full stabs it results in a little stutter before power. On rolling stabs touching the 100% tps later, its smooth an inaudible. 2. immediately after the spike, is a subsequent dip, of equivalent severity. So the if the target here at 0psi when you slam the throttle open is 12.5, you'll see a 14+ followed by a 10-...then miraculously its bang on target as boost comes online and the part stars. So; again, once more. Transient fuel arrives at the party late, and overstays its visit. Increase the synchronous fuel? Ok, same spike, but just makes the dip worse, longer, and rich misfire lol Increase the asychronous fuel, ok, i dont even notice anything lol Mess with the rate table and long the starting tps and rate, doesn't seem to have any effect, besides more rich misfire if you increase, or worse lean spike if you decrease lol Anyone else wrestling with this issue on Haltech? Its not horribly bad if you roll into it smooth. But if you're banging on the car like a new driver, its going to rich misfire, unless you pull out the transient fuel enough to cause lean misfire. Its one or the other. So after reading some more about it, I'm begging to think its time to decrease the "load acceleration rate deadband" setting, which apparently is supposed to be the decay rate. If I understand this correctly, this would mean that the rich dip would be shortened, as the transient fuel will not stick around into load as long. This would then allow you to increase the transient fuel without having the side effect of rich big. Further more the "load rate deadband" sounds like it will enable the transient throttle response early on the throttle touch. My fear with fucking with this is it will induce transient throttle when you're just trying to cruise along. One individual on haltech forums found it to be such an issue on a large throttle with Haltech that he had to run zero dead band, so that the transient trace was always running! Then to counteract the false trips, he ran "disenchriment" when he lifts the throttle, to counteract the trace. If anyone has any similar problems, please share. Would be nice to pass this stuff around. https://cimg3.ibsrv.net/gimg/www.rx7...39dd76942f.png https://cimg2.ibsrv.net/gimg/www.rx7...6f971bf8c0.png |
Hi Monsterbox,
I am not as familiar with the Haltech product line but I was wondering are you able to bring the secondary injectors in sooner lets say -3 vacuum starting at 3000 rpms and up at 30% of the required duty cycle of the secondary injectors? I am finding on alot of my customers this helps big time on high air flowing cars. cheers, Shawn Christenson |
As you've guessed, you need to trigger the acceleration enrichment sooner and reduce the amount of enrichment. You're getting a lean spike because the enrichment isn't triggering early enough followed by a rich spike because there's too much, worst of both worlds and makes the car a dog to drive. As mentioned, how sensitive you can make it will be limited by TPS noise and false triggers. This is typical and not really a Haltech specific problem. If you can eliminate the rich spike it will feel better, but don't expect to totally eliminate any enleanment.
How does the TPS/MAP blend work in the Haltech? Does it still use MAP for the fuel model below atmospheric pressure and MAP for the AFR table? If so MAP sensor lag will be an issue too, how is the MAP filtering configured? |
So theres no way to physically get the hardware to trigger the tranient load earlier, that I can see. All I can do is increase the sensitivity so that it activates it at a lower % per second rate of throttle movement. However, that doesnt matter much as a quick stab, is well, a quick stab and would register it anyhow. So we wind up at the same time regardless.
So my idea, Introduce a 4th axis to the Alpha N table, whereby you have 5 tps tables. Duplicates of the base table. Except, each one above base, is related and only activated for a specific load derivative % per second. So youd have a 25% per sec table, 50 % 100 200 500 1000 etc Now, you try to dial the car as well as possible without going so far as to have too much enrichment on the tail causing the big. Leave the lean pop in there. Now, try to replicate 25% per second at s given rpm and load. Log that lean spike, by logging base fuel map cells, rpm,target lambda and actual lambda, but most importantly load the load derivative %. If for example, you stab, enter transient, and it at 25% per second, at 3000rpm, 65% fuel cell, at 22% throttle, and that's where you see the off target spike. Now you go to the 25% per second 4th dimension copy of the base table, and apply the percentage difference from target to actual afr, to the cell the represents the base cell. So in theory, it's a tps "prediction" value. It calls upon the nee value, on the new tps table, momentarily until transient ends, whereby it returns to the original table. https://cimg5.ibsrv.net/gimg/www.rx7...a6e2bd5bc4.jpg |
In practice triggering the enrichment at a lower TPS delta will improve response, I'd recommend giving it a try. I would turn off async, reduce the percentage of acceleration enrichment and set the sensitivity as low as possible without false triggers and see how that goes.
I like your idea but I think your results will be similar. I have never had much luck with traditional acceleration enrichment and I've tried a few strategies. Adaptronic's MAP prediction combined with X-Tau works okay. |
Ok guys I got it about 90% there. SO MUCH BETTER.
It all turns to this one setting. Make sure you pay attention to this when tuning your haltechs! LOAD ACCELERATION DEAD BAND. This is essentially the decay rate. Techincally speaking, it's the acceleration threashold of throttle movement, that must be maintain, post-initial movement, to continue transient activity. So in other words, the higher your raise this %/second^2, the more rate of foot acceleration is required to continue the transient event. So heres the important part. The range is from 0% to 6,000!!!!%. The manufacture basemap setting is only 120%/sec. Bare with me here, In my scenario. And many others that I've talked to with large throttles, large throttles and semi-pports, big projay, elite intakes etc, many guys are expressing the same issue. A lean spike which may or may not cause a hesitation and a poppy backfire. Then attempt to fix the issue with synchrous fuel/asynchronous fuel. And adjusting the proportion/rate in the rate/load derivative table. What you'll find, is that the synchrous fuel setting, asynchronous, and rate setting have an astronomical range. You see 100s in basemap, but they can go up to 1000 on each cell. Now, to fix the issue, you increase these values, a hell of alot to blunt a big lean spike, but consequentially, you end up with a rich stumble, subsequent to the lean spike. So you end up splitting the difference and settling for less. But the trick I found, is to increase the fuck out of the Load Acceleration Dead Band. As I began to reach 1500%/sec, I noticed that the trailing, rich, dip, began to shrink in duration. I kept going to 2000%/sec and the dip is virtually non-existant. At this point we only have the initial pesky lean spike to deal with... Now that weve rid the motor of the rich dip, and the transient fuel isnt sticking around and misfiring the party, were now able to use exponentially higher values in the syn/asychronous tables. I was able to increase from 180 at 4k rpm to over 350 at 4k rpm. This blunted the majority of the lean spikes. They still occur, but the burst of throttle, that originally caused a 17.0afr for 200ms, now only occurs for 50ms or even less! It's still there, but its virtually unnoticeable, you cant even see it on the racepak. Only in the logs, and no rich tail to follow! So, again, if you are requiring more transient fuel, on the front end, but its messing up your map on the tail end, you need to increase the ever living crap out of that Load acceleration dead band! I found this finally made the full pport turbo engine scream. I can wail into the throttle and it just jumps to life with no misfiring to follow. Such a difficult port design, with low airspeed velocity to manage, but able to be wrestled with this little value. The only downside, and a very important one to note. This severely, I mean severely affects the free rev, and smaller gears. 1st gear and free rev are virtually unusuable. I came off the dyno feeling accomplished after 3rd and 4th gear singing and smashing. Only to flood the hell out of the motor on first restart and free rev 😂 So, to fix this, I added a 3rd dimension to the synchrous and asychronous tables. This dimension is gear position. If you program your gear ratios/calibrate wheel speeds, the ecu will determine whether you're in 1 2 3 4 or neutral or etc. Now you have multiple version of the transient values to play with for each gear! I pulled those 300s 400s crazy shit back down to 100s / original values for neutral and first gear. Split the difference in second, and let her eat in 3rd and 4th. Gave it a quick few revs and a run through the gears and omg shes fucking singing effortlessly. It still needs some playing. It could honestly use some more transient fuel, and even more decay, so it's even more pointed of a burst. She wants it in and out quickly 😂 but theres so much more that can be used if necessary by following this protocal! If the gear position wasnt possible the whole process would have failed, so thankful that axis is possible omg! My only concern is that the ecu gets confused during mid free rev or clutch in while the vehicle is moving. I need to double check but it would be nice to incorporate a neutral switch/clutch switch to be sure we have the response for downshift blipping! Hope this helps ! https://cimg5.ibsrv.net/gimg/www.rx7...d84f153ff3.jpg https://cimg9.ibsrv.net/gimg/www.rx7...9ae0360737.jpg |
Pretty cool. Do you still have the ikea shifter? If yes, do you have the gear indicator that remembers the gear position? If so, maybe you can use that instead of programming the wheel speed.
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Damn. Great development work, David! Fuckin' impressive.
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Originally Posted by shawnm565
(Post 12346132)
Hi Monsterbox,
I am not as familiar with the Haltech product line but I was wondering are you able to bring the secondary injectors in sooner lets say -3 vacuum starting at 3000 rpms and up at 30% of the required duty cycle of the secondary injectors? I am finding on alot of my customers this helps big time on high air flowing cars. cheers, Shawn Christenson So the Elite doesn't really allow you to set a specific RPM target for the transition, but it can be done so secondarily but changing both the min and max staging values that the primary injector must see before engaging the secondaries. So, if you wanted the staging to occur earlier, you'd lower the threashold, forcing the secondaries to come on-line, earlier in the % output of the primary injector output curve. Staging if further tweeked by messing with an overall enrichment percentage that occurs during staging, and a duration value (sort of like an inverse to a decay rate). I'm not really a fan of it, it seems a little overly complex, but its manageable if you sweep through it enough times times on the dyno. I personally like to stage it later, once the car is already starting to come up in to boost, using more fuel from primaries at around 40%, which usually puts it over 4k rpm's as it seems any deviation towards rich from the target AFR that may occur is least noticeable up there, and port airflow is higher. Right about where you said, but with the port of the engine it like that 3k rpm you speak of feels like 4k rpm on this motor. I do see where you were going with this, and so I graphed the Pri/Sec injector outputs in the log, so as to see exactly where the staging occurs during these transient events. It turns out that that the staging occurs immediately following the transient event. They're very close, but the transient seems unaffected by the staging and vice versa. Through process of elimination, the issue came down to too little decay rate, causing overly rich application of the transient fuel where not needed, and simultaneously not enough transient fuel where it was needed. Making the transient event decay away much faster, while increasing the amount of enrichment seems to have really been the kill punch to make it work |
Originally Posted by Monsterbox
(Post 12347508)
Hey Shawn,
So the Elite doesn't really allow you to set a specific RPM target for the transition, but it can be done so secondarily but changing both the min and max staging values that the primary injector must see before engaging the secondaries. So, if you wanted the staging to occur earlier, you'd lower the threashold, forcing the secondaries to come on-line, earlier in the % output of the primary injector output curve. Staging if further tweeked by messing with an overall enrichment percentage that occurs during staging, and a duration value (sort of like an inverse to a decay rate). I'm not really a fan of it, it seems a little overly complex, but its manageable if you sweep through it enough times times on the dyno. I personally like to stage it later, once the car is already starting to come up in to boost, using more fuel from primaries at around 40%, which usually puts it over 4k rpm's as it seems any deviation towards rich from the target AFR that may occur is least noticeable up there, and port airflow is higher. Right about where you said, but with the port of the engine it like that 3k rpm you speak of feels like 4k rpm on this motor. I do see where you were going with this, and so I graphed the Pri/Sec injector outputs in the log, so as to see exactly where the staging occurs during these transient events. It turns out that that the staging occurs immediately following the transient event. They're very close, but the transient seems unaffected by the staging and vice versa. Through process of elimination, the issue came down to too little decay rate, causing overly rich application of the transient fuel where not needed, and simultaneously not enough transient fuel where it was needed. Making the transient event decay away much faster, while increasing the amount of enrichment seems to have really been the kill punch to make it work Cheers! Shawn Christenson |
@Monsterbox
Thank for you the write up..... Just had a question where percent did you end up leaving the LOAD RATE DEAD BAND...? I'm not sure if I should lower it or raise it...... I bumped my LOAD ACCELERATION DEAD BAND to about 800% but my LOAD RATE DEAD BAND was at 38% and notice the FD leaned out during the transient enrichment for a few moments and goes back to target AFR..... I was thinking of bumping it up to 1500% and lowering the LRDB to 20 or 25% I have a log if needed and can also send you my map. LMK |
i'm wondering now if i'm having the same issue... on throttle tip in, just about anywhere in the map, i get a very quick lean spot around 14, followed by a dip into the 10's, then stabilizes, its a real bitch on the track as the car stutters before coming onto power. the really weird part is this didn't start until after i street ported and rebuilt the motor.
i thought it was a staging issue as it always seems to happen around the crossover point 3-4K RPM, so we messed with all kinds of injector staging settings and the problem followed, take a look at my datalog and tell me what you think, the lean spot is right under the cursor line. im also using all the transient settings that came standard with the S6-8 13B map. https://cimg3.ibsrv.net/gimg/www.rx7...72e9fc165b.jpg https://cimg1.ibsrv.net/gimg/www.rx7...7eebdf68fa.jpg |
Originally Posted by Ricebox
(Post 12362138)
the really weird part is this didn't start until after i street ported and rebuilt the motor.
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Originally Posted by C. Ludwig
(Post 12362207)
That's weird? No. Not at all. You changed the flow characteristics of the engine and you're surprised the mapping needed to change?
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Originally Posted by Ricebox
(Post 12362208)
obviously i now understand that the problem is related to that. thanks for the help
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