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wideband AFR at various running conditions

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  • wideband AFR at various running conditions

    My SS is down for repairs and upgrades but I installed the Microtech into my maroon 88 na 2 T along with a wideband O2 sensor and should be up and running next week.For those that have a wideband on your Z what do you consider to be the best AFR for
    -Idle
    -cruise at 15-20 in vac
    -WOT at boost with a max of around 17 psi

    also what timing are you running at
    -Idle
    -Cruise
    -WOT at boost


    My 88 na 2 T has the original engine that was in my SS.8.3:1 Bone stock.
    T04e comp w/ a 60-1 wheel/bored T-3 exhaust housing with an O trim wheel
    TT fuel pump
    420cc injectors
    CM 3" exhaust
    Shiro #443


  • #2
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    • #3
      This is what I've found so far works "best" for my engine.

      -Idle - ~14.0
      -cruise at 15-20 in vac - ~14.7 or closed loop stoich
      -WOT at boost with a max of around 17 psi - I would target about 11.9 for a street car to know you're always in the "safe" range if your standalone does not have fulltime WB o2 feedback.

      also what timing are you running at
      -Idle - 22 degrees
      -Cruise - 45 degrees
      -WOT at boost - 26-28 degrees from 4500+ (7.8:1 comp and 93 octane) For a 9:1 engine I would run a LOT less timing under boost.

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      • #4
        Thanks for the info.I'm using a PLX wideband and the Microtech without any O2 feedback.It's a stock 88t engine with 8.3:1 compression.
        I'm still waiting for my CM 3" exhaust to arrive so I can weld an O2 bung on the downpipe and begin tuning with the wideband.

        Hey Jason what type of engine control are you using on your other Z?
        Shiro #443

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        • #5
          Rick88ss wrote: Hey Jason what type of engine control are you using on your other Z?
          For my 87? It came with a JWT 3bar already installed, so all I had to do was pop out the chip and install the romulator. Then I clamped the WB sensor on the tailpipe and did a little light fuel and timing tuning based on what I had already done on the 84. The difference was night and day.

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          • #6
            Is the JWT program that bad?! I still have the 4 bar 88ecu that I originally installed in my SS but I had too many problems with it. I don't know if it was a bad chip,a bad ecu,or bad wiring,but I double checked everything and even sent the ecu back to Jim Wolf and they said that everything was OK with the ECU but my SS still ran like shit. Is there any way to check it or install another program on the chip and see if the ecu works correctly?

            Thanks,Rick
            Shiro #443

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            • #7
              Rick88ss wrote: Is the JWT program that bad?! I still have the 4 bar 88ecu that I originally installed in my SS but I had too many problems with it. I don't know if it was a bad chip,a bad ecu,or bad wiring,but I double checked everything and even sent the ecu back to Jim Wolf and they said that everything was OK with the ECU but my SS still ran like shit. Is there any way to check it or install another program on the chip and see if the ecu works correctly?
              The JWT program is not "bad" it's just not a optimum tune, it's very generic and "safe" for that generic use. They used to claim they make a program for each person's modifications which is simply not true. The 3bar is one program and the 4bar is another, and that's all I have seen so far. EDITshhhhhhh, but this is about the difference between my tuning and the JWT tune whcih is the before and after at 16PSI: http://www.redz31.com/forum/viewtopic.php?t=13 the same setup with a maf bypass and retune just put down 453rwhp which *no offence ken!!!* took 22PSI on a bigger turbine, with 9:1 comp and race gas for Ken's car to do.)

              Are all the injectors wired correctly and varified to be clicking?

              If the JWT does not run correctly I would say the most likely problem is the fuel injector being larger than they have it calibrated for. Search for info on the fuel injectors, there was a thread a while back on it. They are "supposed to be" 420cc, but mine were easily 460+ that I was running in my 84 before I upgraded to the 550's. Have you thrown your wideband on it?

              Also could be the MAF or related wiring, it seems that the idle voltages can vary a lot. my "cobra maf" puts out about 1vdc at idle.

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              • #8
                All of the JWT stuff was removed from my Z a long time ago.I originally bought the 420cc injectors from JWT(not knowing any better) for $100 each. Maybe I can send you my JWT 4 bar ecu and put your chip in it and see if it works fine.Or will your chip not work because of different MAF? Oh well.I don't wanna sell it to somebody and have it not work right.
                Shiro #443

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                • #9
                  Jason84NA2T wrote: (shhhhhhh, but this is about the difference between my tuning and the JWT tune whcih is the before and after at 16PSI: http://www.redz31.com/forum/viewtopic.php?t=13 the same setup with a maf bypass and retune just put down 453rwhp which *no offence ken!!!* took 22PSI on a bigger turbine, with 9:1 comp and race gas for Ken's car to do.).
                  none taken, my car was far from optimum, I just ran out of money, time, and rear axles.....I would have loved to complete my "optimum" setup...it would own all muahahah :twisted:
                  used to have one of the first high horsepower NA to turbo cam'd 7000rpm pavement pounding z31's....now in process of building an LQ9 LS1 6.0L Z31 with all the goodies

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