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Thread: Considering Going to Open Loop Only - TBI

  1. #16
    Fuel Injected!
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    Open loop is the best way to go if You don't use catalic convetrer. CL is only to protect cat conv not to melt and work properly, all emission related. I run LT1 (92 and 95) OL, with ignition and VE finetuned (i'm MAF delete guy) i was able to get more MPG and power at the same time. CL is always targeting 14.7 AFR (except WOT situation) so you won't get bes overall performance and that limits MPG savings.

    best regards

  2. #17
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    Quote Originally Posted by 1project2many View Post
    But your engine is not so radical that it should need these modifications. Think about a new driver who keeps stalling the truck when letting the clutch out on hills. The new driver blames the hills while the experienced driver sees it differently. You could set out to level all the hills but is that really the right approach?
    I agree, that’s why I’ve been frustrated. 383, Stock vortec heads, cam, valvetrain (except 1.6 ratio rockers, forgot to mention that) and 9.5:1 CR is not radical in my opinion so since I got it running I thought I’d be able to tune all the issues out, but haven’t succeeded yet. I still think I can get everything working right except one issue: the RPM oscillation during decel. That’s really the one issue that has given me the most frustration. OL makes it go away so that’s where I’m thinking of heading. However..... a few days ago my Moates AutoProm arrived and I do plan to dive back into tuning: learn how to use it, incorporate my Wideband data and start trying some different things. I’m wondering if I should try and get my VE table in better shape with WB in OL and then switch it over to CL after that and see where I’m at?

    The Autoprom arrived the day before we went on vacation so I didn’t get a chance to use it - won’t be till next week before I get to try it out.

    Thanks for the input, I do appreciate it.

  3. #18
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    Quote Originally Posted by WASyL View Post
    Open loop is the best way to go if You don't use catalic convetrer. CL is only to protect cat conv not to melt and work properly, all emission related. I run LT1 (92 and 95) OL, with ignition and VE finetuned (i'm MAF delete guy) i was able to get more MPG and power at the same time. CL is always targeting 14.7 AFR (except WOT situation) so you won't get bes overall performance and that limits MPG savings.

    best regards
    Thanks for the input. So what about if there is a cat in the picture? Even though I could get away without in my part of WA state, I did decide to go with one - it’s a straight flow aftermarket type, low back pressure. Will running in OL fry my cat?

  4. #19
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    if You keep cats You should keep CL, CL fueling is mainly for keeping cats safe and opperatonal

    best regards

  5. #20
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    Quote Originally Posted by WASyL View Post
    if You keep cats You should keep CL, CL fueling is mainly for keeping cats safe and opperatonal

    best regards
    Thanks, yeah, I think I'm backing away from my OL only plan. I have driveability issues with both CL and OL, but I think I can live with those on the CL side for now and keep plugging away with tuning to try and minimize them. I have my autoprom now (haven't had an opportunity to try it yet) so I'll be able to adjust parameters on the fly.

    And today I finally found the source of some of my driveability issues, both CL and OL. On the way home today it started idling and light accelerating poorly, which has been an intermittent problem recently. I opened the hood when I got home with engine idling and immediately saw a big blue arc at the plug boot of #3 plug wire. Obviously causing a significant miss. New Delco plug wire set on order already.

  6. #21
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    Got my AutoPROM hooked up and emulating. It was a little tricky trying to get combo emulation/data logging going, but eventually I got it to work. Haven't messed around with trying to read in WB data in to the AutoProm's extra inputs, but that's the next step. Just wanted to see if I could get it to emulate -- tested it by bumping up the idle speed in the bin and sure enough it went up, just a few seconds later. But I'm at the beginning of the learning curve now with real time tuning.

    So...I've posted a number of times about various problems and once or twice about what I'm now going to describe, but this problem has risen to the top of my list now. And I'm not sure it's a problem with the tune. Every 4-5th startup the "engine runtime" field starts with a non-zero number (in the log I made today it started at about 80 seconds) and it starts immediately in closed loop and stays there. When it's doing this my surging while decelerating problem is magnified considerably and idle is 150 rpm higher than commanded. The weird thing is all I have to do to fix this is pull over, shut it off for 20 seconds or so, restart and it runs fine. To me this seems like a hardware issue, not tune, but I have two different '7060 PCMs and I've experienced it with both. Two different MEMCALs too and same thing with both. I've also replaced both VSS units in the 4L80e. PLEASE, if someone has any idea of what is causing this, give me some input. I'm at my wits end on this because it makes no sense to me. Harness issue? Some other sensor that is intermittently acting up? A buffer not getting cleared or reset after the previous shut down?

  7. #22
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    Beginning at $FFC0 to the top of the chip ($FFFF) there are addresses for the ecm to use when various events occur. If one of these addresses is even a bit off you can have very unexpected results. Likewise, a single incorrect bit anywhere in the code can produce surprises. Between opening and closing files and reading and writing calibrations, it's possible for the file to become corrupt. There are tools that will compare two files, byte by byte, and report differences. You might want to start by ensuring your cal is not corrupt. I'm happy to help if you post a cal here.

  8. #23
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    Quote Originally Posted by 1project2many View Post
    Beginning at $FFC0 to the top of the chip ($FFFF) there are addresses for the ecm to use when various events occur. If one of these addresses is even a bit off you can have very unexpected results. Likewise, a single incorrect bit anywhere in the code can produce surprises. Between opening and closing files and reading and writing calibrations, it's possible for the file to become corrupt. There are tools that will compare two files, byte by byte, and report differences. You might want to start by ensuring your cal is not corrupt. I'm happy to help if you post a cal here.
    This sounds like a reasonable explanation and I would be very grateful for some help. I've posted my bin here. Also posted my definition and adx files, but not sure if they're needed or not.
    Attached Files Attached Files

  9. #24
    Electronic Ignition!
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    Hello. Would a wide band O2 sensor be able to log better, more accurate information at idle. Either cold start or warm.

  10. #25
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    Quote Originally Posted by Owl View Post
    Hello. Would a wide band O2 sensor be able to log better, more accurate information at idle. Either cold start or warm.
    yes, because it has wider resolution on signal and mostly shorter reaction time

    best regards

  11. #26
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    Quote Originally Posted by 1project2many View Post
    Beginning at $FFC0 to the top of the chip ($FFFF) there are addresses for the ecm to use when various events occur. If one of these addresses is even a bit off you can have very unexpected results. Likewise, a single incorrect bit anywhere in the code can produce surprises. Between opening and closing files and reading and writing calibrations, it's possible for the file to become corrupt. There are tools that will compare two files, byte by byte, and report differences. You might want to start by ensuring your cal is not corrupt. I'm happy to help if you post a cal here.
    Any chance you've had an opportunity to look at my .bin? If not, would it be worth it for me to just take a clean, stock .bin (AWBP) and swap in all my parameter and table changes? Lots of work and easy to miss something, so probably not the best alternative, but if there are glitches in the base file I'm using might be the only way for me to resolve?

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