won't stay running on 1991 Chevrolet S10

It keeps giving the same 3 codes. map,vss,tps and i replaced all 3. still doesn't what to run.

by in Oklahoma City, OK on June 21, 2010
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1 answer 1 comment
ANSWER by , June 21, 2010
MAP and TPS sensors share the same 5 volt reference signal from the computer (ECM) , have you checked for voltage at these sensors with the key on engine off sensor connection disconnected from the sensor 5 volt should be present at one wire at each sensor or you must trace the wire back to the computer and see if it is a wiring problem , computer problem or power/ ground issue. For test procedures there is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You can get a one week subrcription or year subscription very cheap. The information is year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual try http://bit.ly/mitchell_repair_manuals_online and get an online repair manual subscription.
COMMENT by , June 24, 2010
I checked the wires and the voltage and all good, but when i take the tps off the tpi and hold it to full throttle and hold the vacuum line going to the map sensor it runs good. Im think it mit be the ecm or.. If you have more info.. thank you.