The 3-speed automatic transmission in those cars is not controlled by the ECM, shifting is controlled hydraulically/mechanically. Only the 4-speed transmissions (the newer ones, anyway) are electronically shifted.
Re: PROM question
Jul 17, 2003
1 Replies
Nope, The prom is calibrated for a lot of other variables besides weight. It needs info on the camshaft,compression ratio,injector flow rates,ignition timing,vehicle weight,tire sizes expected,gear ratios in the trans. And a lot more things. That is why you need the PROM for the correct engine. Just like trying to use a 350 PROM on a 305, It will probably run but it won't be correct. Also the 91 trans is not computer controlled.
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