94 gt 5.0 aode swapped to T5


New Member
Feb 15, 2021
Conway AR
So I bought a 94 gt 5.0 that has a 5 speed trans. Since I bought it it's always had this miss or bucking when cruising at highway speeds. I have the obd1 scanner for it and ran codes and I got 637, 654, 621, 622, 652, 624. All of which are for an aode trans. My question is is there a way to wire or bypass pins in my ecu to make it not try controlling the trans or shift timing?
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Unknown. It could be arcing wires, or bad spark plugs, or other misfire or fuel related issues. You’ll need to start troublshooting starting with a possible misfire under load
It shouldn't cause a miss or buck at highway speeds, it will typically cause a bit of hesitation when it reaches the automatic-trans shift-points (due to the timing getting retarded). But at cruise it's likely not the transmission / computer setup. More likely a lean condition - as Mustang5L5 suggests a fuel related issue. Could be O2's, MAF, fuel pressure (pump or regulator or filter - easy enough to test with a gauge). Vacuum leaks or other sources of un-metered air (like the PCV system - especially take note if you have a cold-air-intake). A full tune-up is advisable - plugs, wires, cap & rotor, O2's if they've never been changed, clean MAF, change fuel filter, check fuel pressure. Listing any mods would be helpful too - if everything's in good shape it could be the car was modified but never properly tuned.