Megasquirt More Staging Injection Tuning
07-20-07, 10:13 PM
#1
More Staging Injection Tuning
Ok, staging is working now, as are all the other functions that i'm using. In the logs and when driving occasionally, I do notice that it will go a little lean when staging. Not too lean, but the AFR's jump up by usually around 2 briefly. I have staging cycles set to 50 right now to give a smoother transition, and the primary % number is right on what it should be 185.8 => 186. Its switching off of RPM (3400, delta 200) and kPa (105 delta 10).
It was suggested to link the staging to when the 2ndary throttle plates open, but then I would only have it triggered by MAP and TPS, and id imagine that duty cycles could get dangeroulsy high and/or max out at high speed-low load, Plus, looking at the logs and when the TPS maxes out vs MAP, staging is really never happening when the 2ndary plates are closed anyway, so I dont think that would help.
To me it seems that if I were to increase the primary % number, that it would think the secondaries are smaller and thus for the amount of fuel calculated, higher pulsewidths would be needed. I know this will make it run a little richer once staging happens, but would this (or the opposite, decreasing that number) make the transition more smooth.
What might help here, code-wise, would be either a "start-of-staging" enrichment that would occur when staging first happens, and would allow you to set the enrichment amount in ms or % and time (or cycles) til it decays to 0... or a variable or rpm-based time offset that control how much sooner the secondaries start ramping up before the primaries start decreasing. I wish i was good enough at coding to try to implement this myself, but I really don't know the language well enough.
It was suggested to link the staging to when the 2ndary throttle plates open, but then I would only have it triggered by MAP and TPS, and id imagine that duty cycles could get dangeroulsy high and/or max out at high speed-low load, Plus, looking at the logs and when the TPS maxes out vs MAP, staging is really never happening when the 2ndary plates are closed anyway, so I dont think that would help.
To me it seems that if I were to increase the primary % number, that it would think the secondaries are smaller and thus for the amount of fuel calculated, higher pulsewidths would be needed. I know this will make it run a little richer once staging happens, but would this (or the opposite, decreasing that number) make the transition more smooth.
What might help here, code-wise, would be either a "start-of-staging" enrichment that would occur when staging first happens, and would allow you to set the enrichment amount in ms or % and time (or cycles) til it decays to 0... or a variable or rpm-based time offset that control how much sooner the secondaries start ramping up before the primaries start decreasing. I wish i was good enough at coding to try to implement this myself, but I really don't know the language well enough.
07-21-07, 03:08 AM
#2
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I have been battling this myself for awhile ... the best I have been able to come up with is about a 12-13-12 stage at around 120kpa around 3kish rpm, with a delay around 100(and a rpm stage as you have it at 4k or so, but that has issues as well). I think the completely dry runners, and upstream secondaries have been causing some issues for awhile, there might be something in the works of your idea, but I'm sure it will be awhile ...
07-21-07, 10:47 AM
#3
MegaSquirt Mod
I might try to come up with a few more ideas... although I don't think I'll be able to get them into ms1.
1 is related to EAE, and will be a per-channel EAE enrichment, which when tuned right will automatically shoot a lot more in at first due to the algorithm accounting for there being no fuel on the walls of the intake runner.
The second idea is just to allow a delay setting in engine cycles between when the secondaries start phasing in, and the primaries start phasing out.
Ken
1 is related to EAE, and will be a per-channel EAE enrichment, which when tuned right will automatically shoot a lot more in at first due to the algorithm accounting for there being no fuel on the walls of the intake runner.
The second idea is just to allow a delay setting in engine cycles between when the secondaries start phasing in, and the primaries start phasing out.
Ken
07-23-07, 05:51 PM
#4
im having a problem when 3,800 rpms come on the car bogs (goes really lean according to wideband) almost like i cant rev anymore but ONLY UNDER VACUUM. under boost its fine. i have 550cc/880cc injectors running a zems unit (msI with ms extra)
setings are: Injector settings RPM BASED
staging point: 38
staging off delta: 3
staged scaling factor : 255
staging second parameter : MAP-BASED
Injector 2nd parameter kPA: 105
injector 2nd parameter delta: 10
Injector dtaging delay (cycles): 25
setings are: Injector settings RPM BASED
staging point: 38
staging off delta: 3
staged scaling factor : 255
staging second parameter : MAP-BASED
Injector 2nd parameter kPA: 105
injector 2nd parameter delta: 10
Injector dtaging delay (cycles): 25
07-23-07, 06:17 PM
#5
ok, first off, your scaling factor is very wrong. it should be 197. Its calculated by:
512 * primary injector flow / (primary + secondary flow), so 512 * 550 / 1430 = 197
If it was working well under boost, then your fuel map is probably pretty off, especially under boost at that point. 255 instead of 197 would be telling the MS that your 2ndary injectors are smaller than they really are, so to compensate, it would use a higher PW for the same VE and amount of fuel required. If you tuned the VE table to "account" for this, aka run correctly with the wrong scaling factor, it will be much lower in these areas than it needs to be.
This will make it run very lean in these sections once you correct the scaling factor, so until you bump up the VE table in the areas that it used to run well in, you'll probably go pretty lean, which is exactly what you DON'T want under boost. So if you change the scaling factor, bump up the VE table under boost.
The VE table should turn out very smooth-looking in the 3-d tuning map. My car runs pretty well right now, although it does get a bit rich at high RPMs and high loads, and im still working on my staging stuff.
Also, extending your staging time will help give a more gradual transition, although there will still be a little bit of an initial lean bit as the primaries phase down and the air flowing between the primaries and secondaries doesnt have any fuel in it yet, even tho the secondaries are phasing up.
512 * primary injector flow / (primary + secondary flow), so 512 * 550 / 1430 = 197
If it was working well under boost, then your fuel map is probably pretty off, especially under boost at that point. 255 instead of 197 would be telling the MS that your 2ndary injectors are smaller than they really are, so to compensate, it would use a higher PW for the same VE and amount of fuel required. If you tuned the VE table to "account" for this, aka run correctly with the wrong scaling factor, it will be much lower in these areas than it needs to be.
This will make it run very lean in these sections once you correct the scaling factor, so until you bump up the VE table in the areas that it used to run well in, you'll probably go pretty lean, which is exactly what you DON'T want under boost. So if you change the scaling factor, bump up the VE table under boost.
The VE table should turn out very smooth-looking in the 3-d tuning map. My car runs pretty well right now, although it does get a bit rich at high RPMs and high loads, and im still working on my staging stuff.
Also, extending your staging time will help give a more gradual transition, although there will still be a little bit of an initial lean bit as the primaries phase down and the air flowing between the primaries and secondaries doesnt have any fuel in it yet, even tho the secondaries are phasing up.
07-23-07, 09:33 PM
#7
both have their purpose... I try to initially set things up in the table, especially when looking at overall numbers, making larger changes, or tuning from a datalog, but when street-tuning or smoothing the map, the 3d depiction works great. It also illustrates my point about having a nice smooth, gradual map very nicely, whereas the numbers wouldnt do that as well.
Also, i have that one little row at 200 rpm (the next is at 600 rpm for idle adjustments) and its richer than everything else around it to keep the engine from stalling out when you get off the throttle quickly and rpms drop past idle. It works well when warm, but i still have that problem alot when cold.
Also, i have that one little row at 200 rpm (the next is at 600 rpm for idle adjustments) and its richer than everything else around it to keep the engine from stalling out when you get off the throttle quickly and rpms drop past idle. It works well when warm, but i still have that problem alot when cold.
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07-23-07, 10:23 PM
#9
well, it helps more to keep the engine going when you let off the gas, but I still havent gotten it to not die before its mostly warmed up. I think my enrichment settings are a bit too high when cold, but by the time i've changed them, the engine has heated up.... makes it a little difficult at times.
07-27-07, 10:00 PM
#13
MegaSquirt Mod
You have to have the VE table tuned well before you'll be able to get rid of the jerking when staging.... The gradual staging code can help, but if the VE table is not right, nothing will work.
08-02-07, 08:34 PM
#14
here is another datalog from today.
at the beging its a weird stuble i keep getting, i tried adding fuel to VE map an still does the same. at atroun 2,500rpms goes to 16.5AFR
and alittle after that the staging again going nuts with RPM stting for staging code.
i changed my fuel suply to 203 like was suggested.
at the beging its a weird stuble i keep getting, i tried adding fuel to VE map an still does the same. at atroun 2,500rpms goes to 16.5AFR
and alittle after that the staging again going nuts with RPM stting for staging code.
i changed my fuel suply to 203 like was suggested.
08-03-07, 09:45 AM
#15
MegaSquirt Mod
Your RPM signal should not be so noisy. The noisy RPM signal is causing staging to flicker on and off.
To get rid of this, one thing you could do is make the off-delta larger... like 500 rpms, but you should really figure out where the noise is coming from and fix that.
Ken
To get rid of this, one thing you could do is make the off-delta larger... like 500 rpms, but you should really figure out where the noise is coming from and fix that.
Ken
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