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Need help tuning a GM OBD1 3.1 Turbo

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  • #16
    I will have to get a copy of it posted when I get on my other PC.

    I have a question about the difference between these two tables:
    COLD ENGINE TEMP. DEPENDENT AIR/FUEL RATIO
    AFR VS COOLANT TEMP FOR COLD ENGINE AND CLOSED THROTTLE

    I want to make sure I am understanding this correctly.

    AFR VS COOLANT TEMP FOR COLD ENGINE AND CLOSED THROTTLE
    --> Is this for when the throttle is not being pressed, so the engine uses this AFR to idle?
    --> Is this for open loop only? Or does closed loop also read this table?

    COLD ENGINE TEMP. DEPENDENT AIR/FUEL RATIO
    --> Is this for when the engine is still in open loop? And used when not at idle? Like when the driver is pressing the throttle?
    --> Is this for open loop only? Or does closed loop also read this table?

    I know closed loop uses the O2 sensor feedback.
    Is the scaler number sitting at 14.7 for Stoich AFR the one that the O2 sensor uses to adjust and maintain the closed loop AFR?

    The Main Spark Table, this is always used in both open and closed loop?

    I see tables and I have an idea now about how to tune it, however I would like to understand more about how the computer uses them and when.
    When I know more about how/when its used, I can learn better how to tune them.
    When I know more about the behavior of the engine as a whole, I can use my data logger and have a better understanding of how to tune this for good response and power.


    One thing I noticed, When I adjusted my bin file previously, I noticed it doesn't build boost as fast, where as before, the engine used to build boost faster at lower RPM.
    What is the best way to tune the AFR and spark so that it builds boost quickly for the most response and power?

    I know at WOT it does built up to my max setting which is around 13 PSI, however I can tell, the acceleration is a bit slower off the line because of the longer delay in building boost.
    I used to be able to give it half throttle and it was up to 13 PSI within 1-2 seconds, now it takes about 3-5 seconds.

    EDIT:
    Also, I am slowly figuring out how to adjust the wire pins for my AC and stuff to work.

    I have a few questions about making the TCC work.

    The Beretta wiring harness originally only looked for 2 gear inputs from the 3T40 before it allowed the TCC to engage, those were 2nd and 3rd gear.

    The TGP EPROM, it looked for gear inputs 2nd, 3rd, 4th gear from the 4T60 transmission.
    I wired the 3rd and 4th gear signals into the Beretta 2nd and 3rd gear harness inputs.
    Can I somehow disable the TGP 2nd gear input and bypass it, this way it sees 3rd and 4th gear only, then locks up the TCC based on load and speed?
    Or do I have to somehow figure out how to add a 2nd gear input to this ECM as well?

    Is it possible for the TCC code to be set to ignore the gear inputs and only work based on mph, throttle angle, and engine load?

    I know when GM released the 2.8L V6 in the 1988 Beretta, they did this, the TCC engaged correctly without the use of transmission gear selection feedback.
    Last edited by GHOSTOWLGRID; 10-14-2015, 07:12 PM. Reason: added

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    • #17
      On the 1227730 ECM, trying to make the TCC work.
      Finally got something, but I need someone to verify if this is correct because I have no TCC response still.

      This is what I have:
      2nd gear input - D4
      3rd gear input - D15
      4th gear input - D14

      TCC command - F6

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      • #18
        have you tried manually engaging it to confirm that it actually works? it isn't too common with a 4T60, but I've seen it happen before.
        1995 Monte Carlo LS 3100, 4T60E...for now, future plans include driving it until the wheels fall off!
        Latest nAst1 files here!
        Need a wiring diagram for any GM car or truck from 82-06(and 07-08 cars)? PM me!

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        • #19
          Have you got the MPH to display correctly yet? Without that the TCC will not function.

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          • #20
            I was directed to this thread:


            I wired an adapter for the Beretta so it can use the TGP ECM box. Still no TCC or A/C.
            (Turns out the A/C line I was using on the 1227730 was wrong and acted like a short to ground, I removed that change.)

            Unplugging the ECM made my chip forget, the car stalls again, wont hold an idle anymore.

            Turns out I was using TunerPro wrong, the data log I thought was a data log, that was not a correct data log.
            So What I made is probably way off.

            I am doing some checking, I am thinking its possible I have a failed MEMCAL from the TGP.
            Is there anywhere where I can download the 90 TGP bin file and try it?

            I find it hard to believe that the 90 Beretta MEMCAL runs it fine at idle and the TGP MEMCAL can't keep it idling at all.

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            • #21
              I had the $8f TGP code on a 27c256 eprom on the old 2.8l memcal and worked great in my 88 GTU beretta. TCC and speedo. I even used a JeffM. TopGun160 chip and worked great too. Only time it didn't is when I went to flash. I think it was a 28c256 can't remember. But went into limp mode and ran like a LAF equinox. Two of the pins on the chip were needed to be switched. A/C I didn't mess with because my compressor case leaked out freon and never fixed it. Its the way the A/C switches work thats different between both cars. Was going to hard wire the W-body switches but oh well.
              I say try some ford yellow top 19lb injectors. Maybe those TGP injectors are no go anymore. TGP guys and myself had a hard time with them. Once you eliminate the injectors and runs fine then tune for larger injectors. Make sure your plugs are still good. Invest in a wideband O2 sensor like Innovate or like. You also wired in the Intake Air Temp Sensor on the manifold?

              Only wiring mods I did to the beretta wiring was added boost control wire to the ecm and tapped into the Maff wiring for the IAT sensor. 88 had Maff.

              Forgot to mention. You do need to wire the 4t60 wiring with the 4t60 connector. The 3t40 plug is pinned wrong I belive. So grab that plug off the TGP and wire it in. I looked at mitchell wiring diagram and its shows a 2nd gear switch but I found the TGP wiring diagrams and it only has 3rd and 4th wiring. Your using the 4t60 range sensor?
              Last edited by TurboGTU; 10-29-2015, 06:45 AM.
              88 Beretta GTU turbo . 90 Black ASC/McLaren TGP, awaiting 4t80. 2003 Grand AM se 3400/4t45 daily grind.

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              • #22
                It was a vacuum leak this whole time.
                Plastic hose under the intake cracked.

                I hard wired the A/C to come on and I have a separate fan switch.

                The fuel injectors were purchased brand new, the old ones were aftermarket and not even 22 lbs. Plus they were broken.

                The transmission, I wired up 2nd, 3rd, 4th into the 7730 ECM and it works great. Torque converter finally works. The 4th gear input was needed to be on the correct pin this whole time.

                A nice person named adam is making me a wide band tune for my wide band O2 I bought. This way it can be better tuned later.
                For now he gave me a great base tune and I have been running it on about 14PSI.

                Works so well that I broke the 440-t4 (4T60-HD) transmission I am using.
                Its getting rebuilt with all performance internals at the moment.

                Yes, it uses the 4t60 range sensor, reads correct speed.

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