strange loss of power P30 454
P30 1991 454 Chevrolet with TBI. Banks Kit, Passes CA. smog test. Normally runs fine. When pulling a grade, at about 3/4 throttle "there is no more power increase " If I back off the throttle the pow...
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Check how far the throttle valve opens. It is possible that it is opening beyond vertical. Measure the voltage on the throttle position sensor. Make sure it is still changing throughout the full travel. Voltage will top out at 5 volts. Mixture enrichment happens at 90% throttle. If it is hitting too soon, wide open throttle will not be tuned correctly, because as soon as it hits mixture enrichment, it is no longer in closed loop mode. Don't know if that engine uses MAP, or mass air flow. Speed density (mass air flow) sensors can get dirty and stop working correctly.
