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Thread: new $EE tuning thing!

  1. #1006
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    Quote Originally Posted by spfautsch View Post
    Thanks - I haven't compared to what I did yet but I probably skipped the step of saving the bin before trying to apply the patches.

    I really need to rip the wound back open and delve into some of the machine code. I'd really like to have a better understanding of what you did here b/c there are a half dozen similar hacks I can think of that might take some of the guesswork out of tuning for headers in closed loop.
    The hardest part was to handle the spi communication between t and e side. Since most of the interesting engine stuff is on e-side and the mode 4 message is recieved by t-side you have to transfer some data between them. Luckily I found two unused bytes and didn`t sacrafice other functionality. The slots are full now and controlling anything else on eside will wipe something else.
    Good news is most of the closed loop controls are on tside.

    The strategy for controlling 1d table is to copy the table to ram. Change the values at ram and use a switch byte to alternate between rom and ram table. If you want to change a calculated value you can add delta change adder to final value or make it an absolute value by switches.

    What do you mean by other parameters. T-side is limited by resources and we need to get creative.
    I found that the biggest problem is to get a stable closed loop idle. I have a very stable afr readings in open loop idle and when switching to closed loop either in maf or SD mode I got false rich conditions and PCM substract fuel almost to 17 AFR and the engine wants to die.

    What are the most important parameters controlling this behaviour that needs to be tuned.

  2. #1007
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    Quote Originally Posted by kur4o View Post
    I found that the biggest problem is to get a stable closed loop idle. I have a very stable afr readings in open loop idle and when switching to closed loop either in maf or SD mode I got false rich conditions and PCM substract fuel almost to 17 AFR and the engine wants to die.
    I don't think you're alone in having experienced that phenomenon.

    Quote Originally Posted by kur4o View Post
    What are the most important parameters controlling this behaviour that needs to be tuned.
    All due respect, you're certain to have a better grasp of it than I do. Integrator delay jumps to top of mind. I haven't thought about closed loop PID tuning for a couple weeks now so it's sort of fuzzy for me, but it seems like it would be easier to fine-tune without having to reflash the ECU in between changes. O2 switching threshold may be another good candidate. Long story short, tuning a PID control loop such as this is a complex subject requiring a good bit of knowledge to master.

    Don't take this to mean I'm asking you to go off on an adventure trying to code things for my whimsy, I respect your time and I'm absolutely not asking that. Think of it more like I'm thinking out loud about what I perceive as the most difficult things to tune.

    I'm relatively sure that a stable closed loop idle with headers and a moderate cam (more than 30 degrees overlap) is going to be more or less un-obtainable. I thought I was relatively close with my setup, but I've yet to get a wideband so have no other benchmark to go by other than the seat-of-pants dyno telling me it's relatively smooth at idle with the a/c on.

    I think the biggest challenge is closed-loop operation between idle and your cam's lowest advertised torque spec (i.e. use with xxxx rpm stall convertor). For me that's about 2200 rpm, which is basically the entire cruise range for my particular engine / chassis. It's my theory that integrator oscillation in this range is my biggest source of false (and / or not so false) knock events.

  3. #1008
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    Quote Originally Posted by spfautsch View Post
    I don't think you're alone in having experienced that phenomenon.
    Evening guys,
    Nope, you are definately not alone.

    My biggest problem problem is deciding whether any changes are better or worse.
    This thing will idle at 10.5:1 and 18:1
    Timing between 20 & 40 degrees
    It'll idle down to about 500 rpm when the IAC zeros out.

    Everytime i change something, it just sounds different

    The off throttle surge is still there.

    Ran it last week with the stock tune (and O2 settings) and it was noticably better but still there
    I've just pulled all the timing down to mid 20's and it's still there.
    IAC vs mph tables were earlier maxed at 6. so just been out with them raised from stock 20 to 22 and it was horrible so next i.m trying 3's to see if that makes any diffrence.


    All due respect, you're certain to have a better grasp of it than I do. Integrator delay jumps to top of mind. I haven't thought about closed loop PID tuning for a couple weeks now so it's sort of fuzzy for me, but it seems like it would be easier to fine-tune without having to reflash the ECU in between changes. O2 switching threshold may be another good candidate. Long story short, tuning a PID control loop such as this is a complex subject requiring a good bit of knowledge to master.

    Don't take this to mean I'm asking you to go off on an adventure trying to code things for my whimsy, I respect your time and I'm absolutely not asking that. Think of it more like I'm thinking out loud about what I perceive as the most difficult things to tune.

    I'm relatively sure that a stable closed loop idle with headers and a moderate cam (more than 30 degrees overlap) is going to be more or less un-obtainable. I thought I was relatively close with my setup, but I've yet to get a wideband so have no other benchmark to go by other than the seat-of-pants dyno telling me it's relatively smooth at idle with the a/c on.

    I think the biggest challenge is closed-loop operation between idle and your cam's lowest advertised torque spec (i.e. use with xxxx rpm stall convertor). For me that's about 2200 rpm, which is basically the entire cruise range for my particular engine / chassis. It's my theory that integrator oscillation in this range is my biggest source of false (and / or not so false) knock events.
    My O2's read rich, my Wideband says lean.
    I just forced 14.7 AFR in EEHack tonight and the difference in the AFR graph was huge.
    The motor didn't sound much different though.

    It does like fuel and timing though... mmm that rings an alarm... perhaps I try the OL tune again.

    Can you repost a link to the newer version so I can have a play.

    Cheers
    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  4. #1009
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    if you run open loop, will it still get closed loop timming?

  5. #1010
    Fuel Injected! Terminal_Crazy's Avatar
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    How do you mean?

    The timing stays the same, it’s the fueling that changes.
    OL fueling is just calculated off tables
    CL fueling uses the O2’s feedback to average 14.7.

    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  6. #1011
    Fuel Injected! steveo's Avatar
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    Quote Originally Posted by ony View Post
    if you run open loop, will it still get closed loop timming?
    if you have stored long term trims and switch to open loop, in some conditions they're used

  7. #1012
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    I haven't got the newer ecm or pcm but the 288 has a table for when it restarts in open loop for added or subtracted timming

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