Hey, i just took my 83 Z (305) out for a little drive the other day and when i rev it up past 3000 rpms while idling or driving it starts to miss really bad. I'm getting a code 42 or 43 (cant remember) I just got a heated o2 sensor (i just put lt's in) so i'll see if that makes a difference.

any ideas as to what could be going wrong?

 

42. Fault at electronic spark timing circuit OR
Fault at direct ignition system OR
Fault at fuel cutoff relay circuit
43. Low voltage at electronic spark timing circuit

Pull the codes again, and remember this time, then you will have a starting point.

 

Any idea what would cause this?

 

coil, cap and rotor, spark plugs, wires

 

I just replaced the coil, cap, rotor, plugs and plug wires. basically everything except the ignition module.

I found out that my battery was bad- it wont hold a charge, would this cause my problems?

 

Doesn't the ignition get all its power from the alternator once its started? Change the battery if its bad and see if that fixes anything, you need to do it anyway. Your sure its your battery not holding a charge, and not a bad altenator right? I doubt all your wires or plugs would have went bad at once, you probably didn't need to do those.

Have you pulled the codes again yet to determine what is wrong?

 

Doesn't the ignition get all its power from the alternator once its started? Change the battery if its bad and see if that fixes anything, you need to do it anyway. Your sure its your battery not holding a charge, and not a bad altenator right? I doubt all your wires or plugs would have went bad at once, you probably didn't need to do those.

Have you pulled the codes again yet to determine what is wrong?

 

Diagnostic is hard to perform without being able to rule out as many things as possible. Fix battery first and see if that helps. My old car died because the alternator was not charging the battery and it slowly wound down.