I have a 95 z28 a4.. The number 5 cylinder has a misfire or should i say no fire.. new plugs hot spark. No pulse to the injector. I unplug it while running and no change.. already pulled the pcm and check the circuit from the pcm to the injector and its seem good.. also have power to the positive side of injector.. I connected a test light to use as a noid light but no pulse.. also connected ohm meter to chec but still doesnt seem to show a ground pulse... does this mean my pcm is at fault... it ran good the other day... pleas help its driving me crazy...

 

I would try moving the injector to another cylinder and see if the problem follows the injector. Or you could pop the fuel rail off(with injectors still connected) and see what the injector is doing, i.e. not spraying, dumping fuel, or pulsing correctly. It is very unlikely that the pcm is the problem as I would think if something was wrong with the injector driver circuit, that none of them would work, but I could be mistaken on that. If the problem follows the injector or its not spraying when you pop off the rail then you have your issue and would procede to replace said injector.

If that is your issue, then it would be a good idea to send them all out with the new one and have them cleaned and flow matched to insure OE performance across the board.

 

Use the ohm meter to check the resistance of the injector, with the harness wire off. Should be in the range of 12-16 ohms.

A faulty injector circuit should set DTC 18. Have you scanned the PCM for codes?