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Thread: 2 bar tune for Turbo LT1 F-body possible with '93 ECM? DA3

  1. #31
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    Quote Originally Posted by steveo View Post
    i can dig into other stuff that uses map to see if adjustment is necessary

    i'd like to say we can set baro to a static value for a boosted engine, assuming it isnt going cross country (or maybe even if it is)
    Thank you, thank you , thank you SteveO and Xnke for thinking about / looking into this for me. Looks like there's a few items in there to get me in trouble!

    So you could potentially set baro = 100 manually, but I'd still use the 2 bar MAP and set all the tables as such, where 55kpa = 100 in reality?


    I don't have much to offer in the way of solutions, as I just don't understand the code and how it works. (but I can test it! ) Is there somewhere you would suggest that I could learn up on this?
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  2. #32
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    Quote Originally Posted by steveo View Post
    $003F is the memory address of baro pressure volts

    at C366, we see:

    C366 : LDAA $00DA
    C368 : STAA $003F

    00DA is the map pressure (isn't it cool they put a speed density ECM's MAP memory address the same as its mask? im probably the only one that finds this cool.)

    this is probably inside the barometric update subroutine, now just need to analyze the conditions and branches that reach this code to figure out how to disable.

    or be super evil and just patch 'er like this:

    C366 : LDAA $003F
    C368 : STAA $003F

    also found this,

    E5E4 : LDAA #$FF
    E5E6 : STAA $003F

    this is probably a barometric initializer, sets baro to max, perhaps set this to $7F for a 2 bar system?

    more research required.
    Like all this, how do I learn about all the code etc.? Might as well be Chinese.
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  3. #33
    LT1 specialist steveo's Avatar
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    Quote Originally Posted by hotrodf1 View Post
    Thank you, thank you , thank you SteveO and Xnke for thinking about / looking into this for me. Looks like there's a few items in there to get me in trouble!

    So you could potentially set baro = 100 manually, but I'd still use the 2 bar MAP and set all the tables as such, where 55kpa = 100 in reality?


    I don't have much to offer in the way of solutions, as I just don't understand the code and how it works. (but I can test it! ) Is there somewhere you would suggest that I could learn up on this?
    if running fixed baro i think you'd set it to something like 50kpa (7F)

    these are all motorola 68k instructions, look up a tutorial on 68k (aka 68000) assembly code online somewhere, there are lots of them

  4. #34
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    Quote Originally Posted by steveo View Post
    if running fixed baro i think you'd set it to something like 50kpa (7F)

    these are all motorola 68k instructions, look up a tutorial on 68k (aka 68000) assembly code online somewhere, there are lots of them
    Ok I’ll check it out.

    And the ecu currently reads 55.4 kpa as the baro reading. So if we set it to that my current tune and all would remain valid I think.
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  5. #35
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    Quote Originally Posted by steveo View Post
    i can dig into other stuff that uses map to see if adjustment is necessary

    i'd like to say we can set baro to a static value for a boosted engine, assuming it isnt going cross country (or maybe even if it is)
    Hello Steveo,

    I've been looking at the disassembly some with the code you referenced in previous posts. I can at least find it in there, big step for me LOL. Currently reading up on the Motorola 68k stuff. Learning curve for me, I'm certainly not a programmer.

    Where do we go from here?
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  6. #36
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    More parts have showed up. Hotside stuff will all be here in a couple days.

    Any time to look into the baro update deal Steveo?
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  7. #37
    LT1 specialist steveo's Avatar
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    i took that DA3 xdf and added a patch for what we discussed earlier, so apply that patch, then modify the scalar named ** BAROMETRIC INITIALIZER

    i -think- that will force whatever initial baro value you set. please test it, even key on engine off just to see if the initializer holds.

    i also noticed that the xdf is a bit error prone, for example the map threshold for PE entry had no conversion on its value (i added a conversion), just be wary of any MAP related parameters that dont max out at ~105kpa, they might not have their math done properly.
    Attached Files Attached Files

  8. #38
    LT1 specialist steveo's Avatar
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    just to detail what we're doing with this hacky fixed baro patch (want to modify as little as possible)

    - @0xC366 instead of setting baro=map during its update routine if conditions are met, it simply sets baro=baro and moves on.

    - @0xA3CF during the keep-alive (or other update) routine (which ensures map never exceeds baro), it compares map to baro, but doesn't actually store the value (i just changed STAA to LDAA, so it's loading the value again and continuing on)

    - @0xE5E4 we override the initial value for BARO (0xFF / 104.5KPA) to a new fixed value (about half of that for your two bar thing)

    keep in mind the bin offset is 0x8000 and disassembly addresses are relative to 0x0000.. so if you're looking at the bin, subtract 0x8000 from the addresses above

  9. #39
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    You da man Steveo!

    Thank you for the help. I have found a couple resources for operations / coding / instruction for the 68HC11, but still so much to learn. The computer science stuff I took in college was FORTRAN, and I remember about none of it LOL. So cool you are able (and willing!!) to help me out and make this work. I still can't believe TunerPro is out there, and these files are available, basically for free.

    Anyhow, tonight I got it loaded onto the EEPROM per your instructions, and tried key on engine off first. Baro was showing 54.63, which is what I had set it to in the scalar var. you put in the XDF ( ** BARO INITIALIZER ). So far so good . . .

    Then decided to start it, and see what happens. No drama! She starts and drives just like before. I didn't have the wideband on it, so not sure if the A/F ratio is right where it was, but it seems close enough for now. After driving for a bit, some cruising, some WOT stuff, etc., the BARO was still the same. So it appears that is working.

    So, is there anything to worry about here, with setting the baro manually like we have? If the weather changes etc., altitude changes, will I have issues with the A/F ratio getting thrown out of whack? I'm sure the Baro reading has a strong influence on the fuel delivery calculation. I have no idea how "sensitive" to a small change in actual Baro it would be. Remember I'm in open loop, so there's no BLMs at work here.

    Also, should I expect to get the "high MAP sensor" code 33 when I go into boost? Obviously can't try that just yet.

    Some of the stainless hotside mandrel bends showed up today. Gettin ready to get serious, not lacking much now.
    Last edited by hotrodf1; 08-10-2018 at 04:56 AM.
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  10. #40
    LT1 specialist steveo's Avatar
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    So, is there anything to worry about here, with setting the baro manually like we have? If the weather changes etc., altitude changes, will I have issues with the A/F ratio getting thrown out of whack? I'm sure the Baro reading has a strong influence on the fuel delivery calculation.
    hell no, a 2 bar map with an 8 bit scale isn't nearly accurate enough for weather barometrics! the stock sensor is about 0.5kpa resolution. with your division you're more like 1kpa per step now.

    think about it, what is your summer to winter kpa variation anyway? now divide it by two since you halved your kpa, i bet it's 0.02 or less.

    tune for high air density, and when air density drops a bit from the weather, the extra juice wont hurt anything.

    large altitude changes are an issue, but keep in mind even if you DID have baro update on startup, you'd have to pull over and restart the car every time you changed altitude, agin, that's why lots of factory turbo cars have a second sensor for baro pressure

    boosted engines don't mind being a bit rich in the short term, all that extra combustion pressure and heat will burn off the excess no problem.

    Also, should I expect to get the "high MAP sensor" code 33 when I go into boost? Obviously can't try that just yet.
    i doubt it ...? but we could just disable that code. i don't think most speed density ECMS throw a default on map errors (if it did, it would probably be pretty nasty in this case)

    if i have more time i'll trace all your map sensor code too and see if i can find anything like that, or other variables that need to be /2

  11. #41
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    Alright, well if you get time to dig further in that would be fantastic. Would be nice to be warm and fuzzy that nothing stupid (or detrimental to the motor) will happen when I get into boost, which will hopefully be graceful and easy to start off with.

    At this point, I'm going to get ready to start fabbing this setup. Hopefully it won't take that long. Famous last words. . . .

    Thank you again for sharing some of your time and knowledge to further the hobby and help me out!
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  12. #42
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    Uh-Oh, Houston we have a problem

    SteveO -

    I am not sure what is going on. I have the turbo setup done, and car was running / driving yesterday. Before that, the 2 bar MAP tune, with the patch installed, was doing seemingly just fine - no issues running it NA with the 2 bar tune. Drove it a fair amount, always started and drove perfect.

    Then yesterday, I drove the car and it ran fine. Didn't get into boost, just did some driving around to start with. All seemed well. I did a couple small things (crankcase breather, boost gauge, etc), and then was ready to do a little tuning, but after that the car will not start (talking a few hours later). Smelled of raw fuel it seemed to me.

    Had some trouble getting my laptop to communicate with the ECM last night, which was alarming, but now this morning I am able to connect (reprogrammed the chip, reinstalled). I find that the barometric is now set at 10.36kPa!! I have no idea how this happened.

    So, then I loaded the tune without the patch, and I think it then updated to current MAP reading (55.0) - which makes sense. So, then I loaded the patched tune back in, hoping that I would see the 54.6 setting in the tune patch, but it's still showing 55.0 via laptop. Does the engine need to be running for the patch to work? The patch doesn't seem to be taking effect, at least with the engine not running.

    Then I thought I'd try the 1 bar tune, with the 1 bar sensor, so swapped all that in, but forgot I now have 60lb injectors, not 32. So perhaps that's flooded her again. That tune was for 32's

    And it still won't start. I have tried cranking a lot without the INjector fuses in, thinking it may be flooded. Did get some smoke out of the tail pipe, and a bit of chugging, but it didn't really try to run. Then thinking I had it cleared out (no more smoke from tail pipe), I put fuses back in, and still nothing. No firing it seems.

    So I guess I need to try to get it running again on the 1 bar tune, 1 bar MAP sensor, and put in the proper injector flow rate to just get it running again and start from there.

    What's so perplexing is why it just all of a sudden decided to go stupid on me. Any thoughts?
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  13. #43
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    Update:
    spent most of today trying to figure this out. Still nothing.
    The odd thing is: the first time it failed to run, it did start for just a brief couple seconds before shutting down, then won't do much. Get a pop once in a while.
    Used the GM service manual to check a few things.
    FUEL:
    fuel pressure when key is on is 50psi, little high, but that's probably because of the 340lph pump in the tank and stock 5/16" return line.
    Have 12 volts at the injector connectors, fuses OK. Also noted blinking test light while cranking, so that system I would say appears to be functioning. Also still think it smells like raw fuel after cranking.
    Thought perhaps it was flooded like I said before, but you can't floor it to clear it out, or pull the inj. fuses to clear it either. I pulled a couple plugs as well, and they weren't really wet with fuel, and no fuel poured out of the cylidner or anything.

    SPARK:
    Using the Scan9495 program, I can see that the opti appears to be giving signals to the ECM.
    I checked spark at #2 with a inline spark tester, and can see some light there, so it also appears to be functioning.

    Tunes:
    I tried the old 1 bar tune that worked well, along with a change to proper injector flow. Still nothing
    Tried the old 2 bar tune that worked well, etc., still nothing.

    The only thing I can think of is it's in the opti somehow. Not triggering the ECM at the proper time or something. Odd that it would just fail all at once?? Per the scan program it appears to work?


    I'm not sure what else to try. The injectors are new in the equation, as is the fuel pump. I can't see how the pump is doing all this. If the injectors decided to all leak or something I guess that could do it? I haven't run the car long at all with the Siemens 60's, but I did drive it for at least 10-15 minutes yesterday morning. So the tune / values etc. were working. A/F wasn't way out of whack either.

    UPdate: Swapped in the old 32lb injectors, and known good tune from before, which again produces the same results. ALmost like a carb'd motor that's got the dist. a couple teeth off. Maybe get a partial puff about once per 2 revolutions or so. Not much happening. ALso tried second ECM again, same results there too.
    Last edited by hotrodf1; 09-30-2018 at 05:12 AM.
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  14. #44
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    Ok it seems the Opti is not delivering spark the way it should be. New cap and rotor on the way. Gonna try the MSD vented conversion style.
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

  15. #45
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    Up and running, with code issue

    OK, so long story shorter, I guess the cap and rotor was the problem. Why it just failed to start all of a sudden, I'm not really sure. Still running the original GM Opti, but now it's the vented style. Cool. Also added a hotter coil for good measure (MSD 8226 replacement drop in). Was able to jump the spark further on my tester than with the stock coil, so it's actually measurably better. Good deal.

    Anyhow, the patch that's in the code doesn't seem to work as intended. It doesn't seem to "set" the baro reading manually as we intended, and the ECM is still updating the baro reading later it seems.

    There is a reason I thought it worked before. When I use the unpatched code, it will update the baro setting as usual - and come up with 54-55 kPa or so based on 2 bar MAP. Then I go and use the patched code it will stay that same reading for a while, but at some point just putting around it will update again. I don't know what triggers this, but it throws the tune way out. Like from idling at 13.9 or so to idling at 15.7. Bam, all at once.

    TunerPro and Scan9495 both report the ECM sees 10.35kPa as the baro reading at that point. (This was what I was seeing when the car failed to start, which sent me down the path of thinking it was fuel related. THey just HAD to be connected right??? )

    The car runs and drives even with the baro set at 10.35, which is surprising to me. But at least it can get home. It's actually not even that lean under boost when this happens, though not where i want to be. But using the patched code, the Baro does not update at key on, so it's kinda stuck at 10.35kPa.

    I'm kinda thinking of trying the unpatched code a little more just to see what it does. Is it possible we fixed something that wasn't broke?

    Or should I switch to unpatched code (to get back to 55kPa) , then go back to patched and try to see what circumstances are triggering the reset of baro reading? I think perhaps I can datalog for a bit, and should be able to see that in the log. Scan9495 seems to work better on my old laptop than TunerPro for some reason.
    Last edited by hotrodf1; 10-07-2018 at 04:51 PM.
    J. Moen
    91 Camaro - NASA American Iron Road Racer #91 "The Menace", carb'd 350, FloTek heads, "because racecar"
    91 Camaro RS - '93 LT1 /T56 swap, 224/224, 60lb Siemens, garage ported heads, VS racing 78/75 turbo, Intercooled

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