Desperate for some Help With Microsquirt, Beyond Frustrated |
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Desperate for some Help With Microsquirt, Beyond Frustrated |
Mblizzard |
Aug 25 2017, 04:54 PM
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#1
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Advanced Member Group: Members Posts: 3,033 Joined: 28-January 13 From: Knoxville Tn Member No.: 15,438 Region Association: South East States |
I have been trying to get my conversion done in time for Okteenerfest. I have run up against a brick wall and just cant seem to figure out what i am doing wrong.
If anyone can help me by looking at my tune files or providing insight it will be very much appreciated. I can get th car to idle but nothing beyond that. Any use of the throttle is less than impressive and almost useless. Meaning it bogs down and does not accelerate at all. I have no clue what i am missing. 2056 with new low impeadance injectors. Bosch Wideband O2 sensor. Really need some suggestions. Not sure if i can post the tune files here. But will try. |
McMark |
Sep 1 2017, 12:48 PM
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#2
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
I can see the logic of both approaches: focusing on the VE table first vs. the AFR table first.
If you're tuning the VE table, it seems to me, you should be open-loop. You then tune via whatever feedback you have available to you (WBO2, dyno, etc) to bring the VE table to 'perfection'. Then you can enable closed-loop, after populating the AFR table with the values you see while running your final tune. --OR-- If you're tuning via the AFR table, you run closed-loop from the start and then tune via whatever feedback you have available to you (WBO2, dyno, etc) to bring the AFR table to 'perfection'. Then populate the VE table with the values you see while running your final tune. But I feel like, from the other responses, that I might be missing something from the picture. James? Jeff? Can you correct or add to my understanding? |
JamesM |
Sep 1 2017, 02:31 PM
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#3
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Senior Member Group: Members Posts: 1,895 Joined: 6-April 06 From: Kearns, UT Member No.: 5,834 Region Association: Intermountain Region |
I can see the logic of both approaches: focusing on the VE table first vs. the AFR table first. If you're tuning the VE table, it seems to me, you should be open-loop. You then tune via whatever feedback you have available to you (WBO2, dyno, etc) to bring the VE table to 'perfection'. Then you can enable closed-loop, after populating the AFR table with the values you see while running your final tune. --OR-- If you're tuning via the AFR table, you run closed-loop from the start and then tune via whatever feedback you have available to you (WBO2, dyno, etc) to bring the AFR table to 'perfection'. Then populate the VE table with the values you see while running your final tune. But I feel like, from the other responses, that I might be missing something from the picture. James? Jeff? Can you correct or add to my understanding? You set your AFR targets before using autotune or the log analyzer to adjust the VE table. The AFR targets are what tuning the VE table is attempting to achieve. With closed loop + AFR targets enabled extra data points are generated as the close loop functionality is varying the pulse width to try and hit the target. This generates data for multiple pulse widths under the same target bin. The amount of closed loop correction applied is being recorded in the log along with the resulting O2%. The analyzer/autotune then uses this data to correct your VE table to the most accurate result possible. Look at it like this: Say hypothetically you are running with closed loop off, cruising under steady load steady RPM (lets say 65 kpa 3500 rpm on your VE map) this would result in megasquirt looking up the value for that VE bin (call it 85%) and then calculating the injector pulse width for those operating conditions (lets say its a 12ms squirt) lets also say that this bin on the VE table is currently tuned too rich so this 12ms squirt occurring at 65kpa 3500rpm produces a burn of 11:1 AFR. You could drive like that for an hour but you would only wind up with a single data point for that bin. That data point being: "A 12ms squirt at 65kp 3500 RPM gives you 11:1 AFR" You can drive forever like that and it will be the only datapoint the analyzer has to work with. The only conclusion the analyzer can make is "needs to be leaner" but there is no data to say by how much. Now lets set proper AFR targets and turn closed loop on: Car still holding at 65kpa 3500rpm Megasquirt does the lookup and produces a 12ms injector pulse that results in an 11:1 burn. That is data point #1 BUT now the closed loop algorithm looks at that output and determines the AFR target is not being hit (lets say the target is 13.5 for cruise) Depending on how you have your closed loop set up after a few misses its going to tweak the pulse width slightly so now we have a data point #2 of 65KP 3500RPM 85%VE with a 3% correction applied produces an 11.8ms pules that results in an 11.2:1 burn. Still not hitting the target, closed loop tweaks again and we get yet another data point in the log. After a short while of running like this we will have one of two results. Either A. Closed loop operation will have resulted in a data point that hits on exactly what we are looking for or B. If the VE bin is further out of tune than the closed loop settings allow for correction we will collect data points on all the run conditions up to that correction limit, but even then the slope of that correction data allows the analyzer to predict what the value should be. the analyzer then kicks you back a new generated table based on the data. Autotune basically does the same thing just with a slower correction rate than closed loop algorithms are usually set to. With a single data point you just have to keep guessing at how much to adjust which is fine if you don't mind spending weeks manually dialing in your map. I find data collection and automated processing a way more enjoyable way to do it, not to mention faster and more accurate. If you change your AFR targets after tuning your VE table you should go back and re-tune your VE table to hit those targets otherwise you are constantly depending on closed loop operation to hit them which is slower and not as accurate as a properly tuned VE table. It puts you at risk of being outside your closed loop limits and should your O2 sensor crap out you will be running out of tune. Basically the goal is to get your VE table to a point that the closed loop algorithm never has to do anything. You know your tune is dialed in when you can run a datalog through the analyzer and have it make minimal to no changes based on the data provided. |
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