"i have 502 mag mpi's.
"i have 502 mag mpi's. very similar injection and let me tell you what i found one day w/ a very similar situation....
the injection fires the injectors in pairs. i had one injector that was bad. shorted to ground. what it did was kill that pair and, i suspect confused the hell out of the rest... and the motor would do exactly what yours does. and the fuel pressure gage woill lie to you because even tho it says you have 38 to 42 psi, two or more of the injectors have stopped working so you are getting zero fuel delivery there. the diagnostic is to pull the injectors and test fire them using the scanner and a make shift hi pressure fuel rig that costs about 2o bucks to make. you pressure the injector and then test fire it and if you get a nice spray pattern then thats a good one... and if you don't then its not.
ive got 20 bucks that says you have at least one bad injector.
also... if you are going to keep that motor, the buy yourself the FACTORY workshop manual... not the seloc or aftermarket trash. get the factory manual and a scanner and if you can read and run a VO meter, you can do these diagnostics yourself. the book makes it a breeze."
"i have 502 mag mpi's. very similar injection and let me tell you what i found one day w/ a very similar situation....
the injection fires the injectors in pairs. i had one injector that was bad. shorted to ground. what it did was kill that pair and, i suspect confused the hell out of the rest... and the motor would do exactly what yours does. and the fuel pressure gage woill lie to you because even tho it says you have 38 to 42 psi, two or more of the injectors have stopped working so you are getting zero fuel delivery there. the diagnostic is to pull the injectors and test fire them using the scanner and a make shift hi pressure fuel rig that costs about 2o bucks to make. you pressure the injector and then test fire it and if you get a nice spray pattern then thats a good one... and if you don't then its not.
ive got 20 bucks that says you have at least one bad injector.
also... if you are going to keep that motor, the buy yourself the FACTORY workshop manual... not the seloc or aftermarket trash. get the factory manual and a scanner and if you can read and run a VO meter, you can do these diagnostics yourself. the book makes it a breeze."
