update:still no go

[savannaz34]

hi guys and gals.ive had a prob with my 92 z34,3.4dohc.
only wants to start when it feels like starting,and when it does start it only runs for about 1 to 10 min.i have fuel pressure(aprox45lbs),i have good compression at each cylinder, i have spark,i have injector pulse,i replaced my ecm,knock sensor,crank sensor,icm,spark plugs,ect.i scanned while it will run and wont run,both situations show same readind for all sensors on scanner.ive been at this car for months now.ive talked to numerous local mech's and they all have no idea,well they dont care(no one likes this motor).ive checked vac lines,no leaks.please help me.what am i missing here.and dont tell me to scrap it,because believe you me,i would drop it from the crane at work if i didn't have so much time and money invested.


thanx people
i hope you can help me out

[maxwedge]

When it won't run anymore do you have spark and injector pulse, will it run spraying carb cleaner into the intake?

[kevinb70]

just for grins, unbolt the cat at the collector and see if it'll run. pick up a new collector ring-gasket beforehand. the "gasket" looks like of like a big bangle type bracelet.

any codes?

if you can actually drive it, does it misfire on heavy/moderate acceleration?

[Bearwulf]

When it runs is it smooth or rough? Have you checked the coils? does it maintain oil pres.?

[savannaz34]

hey guys,thanx for the replies.
sorry i took so long reply back.
anyways,when it wont start:yes i have spark,i have injector pulse,and yes it mantains oil pres.could a blocked cat realy cause this problem?
when it is runing:some times run nice and smooth,some times runs rough(but i think i narrowed the rough part down to a loose connection at the map sensor.all three coils are fine(they have been tested,ive been told a bad wire or ground somewhere for the ecu,but i cant see how,when the scanner can communicate with all sensors?its not making any sense what so ever.im open to all ideas,dont hurt to check right?
so if any of you guys can think of a possible prob,plz reply

thanks guys