Megasquirt Part throttle/WOT tuning
09-25-18, 06:07 PM
#1
Part throttle/WOT tuning
Anyone else, have extreme rich events after tuning WOT boost with part throttle boost?
im seeing almost a .5-1 point variance between WOT pulls and driving part throttle, wondering what i can to lean out the mixture during part throttle driving?
aka 40% throttle boost going from 0-7 psi 3500-7000rpm i can see 9.9afr-10.5
and at WOT 80%+ throttle from 0-7psi 3500-7000rpm i see 10.2-11.0 afr
gearing will vary AFR i understand that, but 9.9 (lowest my WB can read) was just wondering im throwing alot of fuel at it for part throttle response. wondering if yall have any insight
cars Streetport s4 turbo
t04r garrett its a little lazy below 3000rpm
50mm wastegate, 1000/2200 bosch ev14 injectors (ID copys)
ms3x Aem 340lph pump
im seeing almost a .5-1 point variance between WOT pulls and driving part throttle, wondering what i can to lean out the mixture during part throttle driving?
aka 40% throttle boost going from 0-7 psi 3500-7000rpm i can see 9.9afr-10.5
and at WOT 80%+ throttle from 0-7psi 3500-7000rpm i see 10.2-11.0 afr
gearing will vary AFR i understand that, but 9.9 (lowest my WB can read) was just wondering im throwing alot of fuel at it for part throttle response. wondering if yall have any insight
cars Streetport s4 turbo
t04r garrett its a little lazy below 3000rpm
50mm wastegate, 1000/2200 bosch ev14 injectors (ID copys)
ms3x Aem 340lph pump
09-26-18, 09:44 PM
#2
Could you clarify a little bit? Are you saying that at 40% throttle and WOT you get the same measured intake pressure at the same engine speed, but the AFR is different?
Does the engine feel like its making about the same amount of power in both of these cases?
Where is your MAP sensor connected to? one of the primary runners, after the throttle?
My first thought is that with the throttle at 40%, the secondary runner throttles are not opening yet, so you aren't getting the airflow from those ports. If the MAP is reading the same at 40% throttle as it is when you're at WOT when the secondary runners are open, the MS will fuel the same amount but you'll have a little more airflow at WOT, meaning the AFR will be leaner. This would also mean the turbo is producing the same boost, even though the total flow is lower, so you probably have pretty late combustion when its that rich that continues to burn into the exhaust, providing the extra energy that the turbo needs.
My recommendation would be to try to lean it out a bit. At 0 - 7 PSI you do not need to be that rich, you're just throwing away fuel and causing drivability issues. At 0 PSI I would recommend being right around stoichiometric. Typically this is nominally 14.7, but it will depend on how you set up your air-fuel ratio meter - I know Innovate products allow you to specify the stoich ratio since wide-band O2 sensors really just sense the amount (positive or negative) of excess oxygen and require the stoich AFR to convert this excess oxygen percentage to an air-fuel ratio. If you want to be more correct, most gasolines with 10% ethanol are closer to 14.0 AFR at stoich, while gasolines without will vary from 14.5 to 14.7, but ultimately this does't matter too much since the O2 correction will take care of differences in this range. As boost increases, you should get progressively richer, to maybe 12.5 or 12:1 AFR at 7 psi, on to 11 AFR above that. Any richer, and you're really just wasting fuel. Not only will this AFR schedule make your engine a little more efficient when you tip into boost, but it should increase responsiveness, help keep you from fouling plugs and building deposits in the engine, and make a touch more power.
Does the engine feel like its making about the same amount of power in both of these cases?
Where is your MAP sensor connected to? one of the primary runners, after the throttle?
My first thought is that with the throttle at 40%, the secondary runner throttles are not opening yet, so you aren't getting the airflow from those ports. If the MAP is reading the same at 40% throttle as it is when you're at WOT when the secondary runners are open, the MS will fuel the same amount but you'll have a little more airflow at WOT, meaning the AFR will be leaner. This would also mean the turbo is producing the same boost, even though the total flow is lower, so you probably have pretty late combustion when its that rich that continues to burn into the exhaust, providing the extra energy that the turbo needs.
My recommendation would be to try to lean it out a bit. At 0 - 7 PSI you do not need to be that rich, you're just throwing away fuel and causing drivability issues. At 0 PSI I would recommend being right around stoichiometric. Typically this is nominally 14.7, but it will depend on how you set up your air-fuel ratio meter - I know Innovate products allow you to specify the stoich ratio since wide-band O2 sensors really just sense the amount (positive or negative) of excess oxygen and require the stoich AFR to convert this excess oxygen percentage to an air-fuel ratio. If you want to be more correct, most gasolines with 10% ethanol are closer to 14.0 AFR at stoich, while gasolines without will vary from 14.5 to 14.7, but ultimately this does't matter too much since the O2 correction will take care of differences in this range. As boost increases, you should get progressively richer, to maybe 12.5 or 12:1 AFR at 7 psi, on to 11 AFR above that. Any richer, and you're really just wasting fuel. Not only will this AFR schedule make your engine a little more efficient when you tip into boost, but it should increase responsiveness, help keep you from fouling plugs and building deposits in the engine, and make a touch more power.
09-27-18, 10:27 AM
#3
Could you clarify a little bit? Are you saying that at 40% throttle and WOT you get the same measured intake pressure at the same engine speed, but the AFR is different?
Does the engine feel like its making about the same amount of power in both of these cases?
Where is your MAP sensor connected to? one of the primary runners, after the throttle?
My first thought is that with the throttle at 40%, the secondary runner throttles are not opening yet, so you aren't getting the airflow from those ports. If the MAP is reading the same at 40% throttle as it is when you're at WOT when the secondary runners are open, the MS will fuel the same amount but you'll have a little more airflow at WOT, meaning the AFR will be leaner. This would also mean the turbo is producing the same boost, even though the total flow is lower, so you probably have pretty late combustion when its that rich that continues to burn into the exhaust, providing the extra energy that the turbo needs.
My recommendation would be to try to lean it out a bit. At 0 - 7 PSI you do not need to be that rich, you're just throwing away fuel and causing drivability issues. At 0 PSI I would recommend being right around stoichiometric. Typically this is nominally 14.7, but it will depend on how you set up your air-fuel ratio meter - I know Innovate products allow you to specify the stoich ratio since wide-band O2 sensors really just sense the amount (positive or negative) of excess oxygen and require the stoich AFR to convert this excess oxygen percentage to an air-fuel ratio. If you want to be more correct, most gasolines with 10% ethanol are closer to 14.0 AFR at stoich, while gasolines without will vary from 14.5 to 14.7, but ultimately this does't matter too much since the O2 correction will take care of differences in this range. As boost increases, you should get progressively richer, to maybe 12.5 or 12:1 AFR at 7 psi, on to 11 AFR above that. Any richer, and you're really just wasting fuel. Not only will this AFR schedule make your engine a little more efficient when you tip into boost, but it should increase responsiveness, help keep you from fouling plugs and building deposits in the engine, and make a touch more power.
Does the engine feel like its making about the same amount of power in both of these cases?
Where is your MAP sensor connected to? one of the primary runners, after the throttle?
My first thought is that with the throttle at 40%, the secondary runner throttles are not opening yet, so you aren't getting the airflow from those ports. If the MAP is reading the same at 40% throttle as it is when you're at WOT when the secondary runners are open, the MS will fuel the same amount but you'll have a little more airflow at WOT, meaning the AFR will be leaner. This would also mean the turbo is producing the same boost, even though the total flow is lower, so you probably have pretty late combustion when its that rich that continues to burn into the exhaust, providing the extra energy that the turbo needs.
My recommendation would be to try to lean it out a bit. At 0 - 7 PSI you do not need to be that rich, you're just throwing away fuel and causing drivability issues. At 0 PSI I would recommend being right around stoichiometric. Typically this is nominally 14.7, but it will depend on how you set up your air-fuel ratio meter - I know Innovate products allow you to specify the stoich ratio since wide-band O2 sensors really just sense the amount (positive or negative) of excess oxygen and require the stoich AFR to convert this excess oxygen percentage to an air-fuel ratio. If you want to be more correct, most gasolines with 10% ethanol are closer to 14.0 AFR at stoich, while gasolines without will vary from 14.5 to 14.7, but ultimately this does't matter too much since the O2 correction will take care of differences in this range. As boost increases, you should get progressively richer, to maybe 12.5 or 12:1 AFR at 7 psi, on to 11 AFR above that. Any richer, and you're really just wasting fuel. Not only will this AFR schedule make your engine a little more efficient when you tip into boost, but it should increase responsiveness, help keep you from fouling plugs and building deposits in the engine, and make a touch more power.
Map sensor is measure off of my FD uim of one of the vacuum ports after the imdieate throttle bottom located close to the bottom close to the firewall,
wide band is a PLX with 4.9 sensor
for example today at 5000rpm 35% throttle 140kpa my wide band reads 9.9afr (lowest it can read)
closest data log i can find quickly at 5500rpm 70% throttle 142kpa my wide band reads 10.7 so a much better afr but comanding the Same VE amount same pulse width same duty cycle
with zero Fuel: Accel Enrich so thats not the couprit, idk maybe just the volume of the pressureized air is different at double the throttle which makes sense, just stupid rich
car accellerates well at the 9.9 reading drives right threw it doesnt fall on its face but deff isnt a peppy obviously then the 70% throttle lol
i will see if i can get a data log this evening of both and post it
10-29-18, 01:32 PM
#5
Old [Sch|F]ool
I think your MAP sensor location needs to be addressed. Make sure wherever it gets vacuum from is sensing the plenum for the primaries, not the secondaries.
12-03-18, 06:45 PM
#6
Its been awhile! sorry haha i got busy at work cause it turned into tire season didnt drive the car much, vaccuum source is on one of the nipples off the fd intake manifold behind the tpms where i think there are 3 vacuum nipples, i have one blocked off one boost gauge one map signal, where else should i put it? its rather funny to see my VE of 53 go between 9.9 afr and 10.8-11.0
12-10-18, 03:10 PM
#7
Old [Sch|F]ool
I am unfamiliar with the specifics of the FD intake manifold. You need to verify for yourself that the vacuum nipple you chose will go to the primary ports.
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12-13-18, 07:17 PM
#10
Old [Sch|F]ool
Your injector constants have to be FUBAR or something.
I also assume that you are not using separate VE and AFR tables. This isn't necessarily bad, but it makes doing AFR tweaks less simple in the future. (And if your injector constants are wrong, doing this won't work anyway)
(an aside - gearing should not affect AFR! It may affect AFR requirements, as the longer you are under load the more fuel you need for cooling at the expense of power, but the tune should remain unaffected)
I also assume that you are not using separate VE and AFR tables. This isn't necessarily bad, but it makes doing AFR tweaks less simple in the future. (And if your injector constants are wrong, doing this won't work anyway)
(an aside - gearing should not affect AFR! It may affect AFR requirements, as the longer you are under load the more fuel you need for cooling at the expense of power, but the tune should remain unaffected)
Last edited by peejay; 12-13-18 at 07:19 PM.
12-14-18, 11:00 AM
#12
Your injector constants have to be FUBAR or something.
I also assume that you are not using separate VE and AFR tables. This isn't necessarily bad, but it makes doing AFR tweaks less simple in the future. (And if your injector constants are wrong, doing this won't work anyway)
(an aside - gearing should not affect AFR! It may affect AFR requirements, as the longer you are under load the more fuel you need for cooling at the expense of power, but the tune should remain unaffected)
I also assume that you are not using separate VE and AFR tables. This isn't necessarily bad, but it makes doing AFR tweaks less simple in the future. (And if your injector constants are wrong, doing this won't work anyway)
(an aside - gearing should not affect AFR! It may affect AFR requirements, as the longer you are under load the more fuel you need for cooling at the expense of power, but the tune should remain unaffected)
what do you nean injector constants? that term doesnt sound familur i may know it as something else
i do have a fuel VE table and a AFR table
i dont have any fuel trims in effect or ego correction as trying to get fuel set before that, i wounder if i have my injectors stagged too soon as i do have 1000cc primarys and 2200 secondaries possiblly just soaking the LIM with fuel and the atomizeation isnt as good? im not sure,
i am runing a FPR raising rate! should be 1-1
12-15-18, 07:35 AM
#14
i mean 1-1 as every psi of boost i goes up 1 psi of fuel pressure sorry miss comunication
also it might be necessary to note im running stock fuel pressure so 38 psi with out the fpr connected to vacuum, i just recently read somewhere
that id injectors require a higher base fuel pressure? is this any reason for concern? maybe my issue?
also it might be necessary to note im running stock fuel pressure so 38 psi with out the fpr connected to vacuum, i just recently read somewhere
that id injectors require a higher base fuel pressure? is this any reason for concern? maybe my issue?
Last edited by dillrx7; 12-15-18 at 07:39 AM.
12-16-18, 11:23 AM
#17
Old [Sch|F]ool
That will have an enormous affect on your tune's repeatability. Getting the injector constants correct is the first thing that needs to be done correctly because everything else depends on that being correct. If the injector constants are not right, then the compensation for air temp will be wrong, acceleration enrichment will be wrong... basically everything that the computer does.
You WILL have to basically start over from scratch.
You WILL have to basically start over from scratch.
12-16-18, 12:29 PM
#18
That will have an enormous affect on your tune's repeatability. Getting the injector constants correct is the first thing that needs to be done correctly because everything else depends on that being correct. If the injector constants are not right, then the compensation for air temp will be wrong, acceleration enrichment will be wrong... basically everything that the computer does.
You WILL have to basically start over from scratch.
You WILL have to basically start over from scratch.
im okay with that, ive already implemented the changes on my side in tuner studios now i have to wait till spring to see what it does anything else look odd? if u took a look
12-16-18, 03:47 PM
#19
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1000 cc injectors are quite large for primaries. You'll probably always have a difficult time getting really smooth operation for all the low-horsepower scenarios. Have you considered going smaller?
12-16-18, 08:20 PM
#20
going smaller isnt needed,
power goals is 400ish on lower boost 15-17psi or where ever that takes me,
at some point im aiming for mid 500s later on when i can drive the car at 400
12-18-18, 08:27 PM
#21
Old [Sch|F]ool
I have 1200cc injectors as "primaries"... really the only injectors, since I only run two. No real issues other than aftermarket injectors generally being junk unless you buck up some Injector Dynamics money.
I still sometimes feel like ditching the aftermarket garbage and running the GSL-SE 680cc injectors at 65psi instead of the stock 37psi.
Last edited by peejay; 12-18-18 at 08:30 PM.
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