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  • no shift under high rev

    ok, i just had opti , plugs ,wires,headers done. it idles good , no stumbles drives good , shifts fine as long as i dont hammer it. however under wot it seems to hit a rev limiter at about 5000 to 5200 rpms. once it does that it seems to lose power and wont shift until i let out of it. if i stomp it from a dead stop while in gear it just goes to hitting this "rev limiter" and wont shift. tranny fluid is ok , a little dirty but it has always been serviced regularly, due to a bad mechanic this is now the third opti on the car. any input would be great. thanks
    1995 Z28 A4, SCC Ultra Z Hood with Air box/K&N filter, Granatelli Maf Sensor/Fernco bellow/Hotchkis STB/white face gauges/LT4 Knock module/March pullies/160* stat without Hypertech Tunning/Borla 3" y-pipe/HI Flo 3" cat/SLP Loudmouth/GM Motive 3.73's + TA rear end girdle/Afs ZR1's silver painted with polished lip 17x9.5 front & 17x11 out back/98 tail light's/BMR SFC's/spohn Lca's/spohn relo brackets & spohn adj. panhard rod " coated mid lenght pacesetters headers + 1.6rr + custom pc tuning going on soon hopefully "

  • #2
    It's likely an issue with ignition. Stock shift points are set to 5700-5750 RPM, so if something is preventing you from hitting that RPM at WOT, it will never shift. I would suggest looking at your coil or ICM. They could be the issue of cutting out at high RPMs.
    94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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    • #3
      What happens if you rev it with no load? ( in neutral)

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      • #4
        when reved in neutral it revs without issues.
        1995 Z28 A4, SCC Ultra Z Hood with Air box/K&N filter, Granatelli Maf Sensor/Fernco bellow/Hotchkis STB/white face gauges/LT4 Knock module/March pullies/160* stat without Hypertech Tunning/Borla 3" y-pipe/HI Flo 3" cat/SLP Loudmouth/GM Motive 3.73's + TA rear end girdle/Afs ZR1's silver painted with polished lip 17x9.5 front & 17x11 out back/98 tail light's/BMR SFC's/spohn Lca's/spohn relo brackets & spohn adj. panhard rod " coated mid lenght pacesetters headers + 1.6rr + custom pc tuning going on soon hopefully "

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        • #5
          To me, that signifies that under load, you're experiencing the issue. I had the exact same thing for years, except mine was around 5400-5700 RPM. It was an ignition issue.

          After I had the ignition issue taken care of, my tranny was not shifting, but what happened is that it would rev all the way up to 6350 RPM - that shows that my revs were well past the shift point and above the rev limiter - signs your tranny is going south (especially on the 2-3 shift).
          94 Black T/A GT, Advanced Induction 355, 3200 stall, built 4L60E, Moser 9", Baer Brakes, Shooting for 11s...

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          • #6
            The mixture becomes harder to fire as the combustion chamer pressure increases. Since more air/fuel is entered into the cylinder when in gear and accelerating, the ignition will find the path of least resistance. That could be plug wires to ground.

            you said that the opti has been replaced. Did you happen to put the metal boot covers back on the plug wires?

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            • #7
              was the entire opti changed or just the cap and rotor? my bearing went out on the opti by that optical sensor which threw rust and debri in that sensor and it did that when racing it seemed to cut out and no pull anymore. in the rpm range ur talking about. just curious, but once i replaced the entire unit it has ran better than ever.
              '97 Trans Am - B&M Short Throw - B&M Line Lock - k&N Cold air - 6 speed - Lt1 T-Tops - Lowered

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              • #8
                Just a thought, but every GM car I ever had at one point had a problem with shifting at WOT. Carb work, tranny rebuilds and tons of bills later on my first GM and it turned out to be the Cat. Converter. So now naturally after checking to make sure a spark plug isn't loose or grounding out anywhere, my first instinct is a clogged cat. For some reason this happens to be the case everytime. Hoping maybe this will help.
                1995 Pontiac Formula Firebird 383 Stroker 11.5:1 compression, ASM Thottle body, Custom Grind Comp Cam, MSD ignition, BMR strut, k-member, Upper and Lower control arms, rear control arms, and still a work in progress.

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