95 z28 shuts down on road

[jmed95z28]

i have a 95 z28 m6 it will run for a little while (couple miles - couple hours) then it will cut off after a few hours it will start back and run good until it does it again i am losing spark when it shuts down but i dont know why i have changed the opti, pcm, ignition control module, and coil. i have no leaks that could be getting into the opti and shutting it down i am lost on this problem and any advise would help thanks

[IronOutlaw]

Have you checked the fuel pressure when it wont crank?
Id rule that out just to be sure.

[Toronto_LT1]

my car did the same thing for a few days then the fuel pump took a dump on me.

[Bad Karma]

[superman music}
http://shbox.com/1/4th_gen_tech2.html#opti_test
[/superman music}

lol...try this troubleshooting method. Should help you out considerably.

If you can test FP right away, Id try that first then rock into this.

Good luck and keep us posted. Alot of threads here with NO START conditions.

Look around brother,
Ivan

[KissMyWhtSS]

[superman music}
http://shbox.com/1/4th_gen_tech2.html#opti_test
[/superman music}:jest: And yeah I'd check with fuel pressure to ensure that's not the problem as the fuel system is easier to diagnose than the ignition system.

[jmed95z28]

its already got a new fuel pump and pressure regulator i have 48 psi at the rail but when it cuts off i am losing spark

[Fastbird]

Couple of things come to mind. PCM or ICM overheating. Maybe get a spare of each and next time it cuts out do a quick swap and see what happens.

[jmed95z28]

thanks to everyone for the advise i didnt lose spark it was just very retarded i tested my knock sensor and it wasnt functioning properly i replaced it and for the last 50 miles it has done very good thank all of yall again this is a great forum