high idle

i have a 92 chevy caprice 5.0L 305 with a high idle and a error
code 51 faulty or incorrect prom.(memcal).
can i replace this myself or do i let my dealer charge $500 to replace it? have already replaced idle air control valve twice fixed problem for a few hours and then got error code 51 again

i have a 92 chevy caprice 5.0L 305 with a high idle and a error
code 51 faulty or incorrect prom.(memcal).
can i replace this myself or do i let my dealer charge $500 to replace it? have already replaced idle air control valve twice fixed problem for a few hours and then got error code 51 again


code 51 may mean the ECM/computer is defective ..you should be able to get a replacement at scrap yard or auto store ..the dealer would not be the place to go...

I would make sure with a vacuum guage you have no vacuum leaks...check all hoses/pcv etc...

then make sure all ecm connections and grounds all in the engine area are clean no rust or green corrosion including the ecm connector pins. then scrap yard for part/ecm...this should be less than 100.oo..

thank you for answering so quickly. does this mean it does not need to be hooked up to a computer? can i simply install the new prom in the pcm or should i replace the whole thing altogether? while driving today the idle dropped to normal and has been fine allday. should i still replace the unit?

thank you for answering so quickly. does this mean it does not need to be hooked up to a computer? can i simply install the new prom in the pcm or should i replace the whole thing altogether? while driving today the idle dropped to normal and has been fine allday. should i still replace the unit?

follow my suggestions ...since this very intermittent it is most likely an electrical connection that is corroded..

ok i will check it out and again thank you