HI, ok, so my old msd box went bad. it was an old model without the gray tach wire. Car wouldn't start... it would turn but it wouldnt fire. it's a 1997 camaro z28. So i bought a new msd 6a box. hooked up the same wires same as before... wa la .... the car fired right up. but on the new box it's got a gray tach wire.. so i didn't hook it up at this point. test drove.. and it sputters in high rpm.. and has loss of power.. just doesnt act the same.. but low rpm it's fine. So I hook up the gray wire this time to the tach car wire.. and now the car won't fire up at all. i disconnected the gray wire again.. and it did fire just like it did before.. then while car running, hooked up the gray wire again to the cars tach wire and the car stalled., What's the deal??

 

Have you tried disconnecting the MSD? Alot of times they are misused and aren't necessary and can complicate an otherwise simple ignition system.

 

What "tach wire" did you attach the gray wire to? The tach is driven by a wire that runs from the PCM to the tach. Only the 93 LT1 had the tach wired from the coil, and that went through a filter.

 

I hooked up the gray wire to the same wire that the nitrous switch tach wire is hooked up to that my mechanic hooked up by the coil. Am i have issues with the car because the gray wire is not hooked up? like i said my old msd box didnt have a gray wire and this one does.

 

you think i should order the 8910 tach adapter? or is something else going on?

 

Have you disconnected the box and try the car and see if it works good without it? You can also check all the connections and see if they are on right.

 

Your "tach wire" is a white wire that runs from pin A13 of the PCM, through connector C230 to the tach.

Is it possible you are attempting to connect to the white wire that runs from pin B5 of the PCM to pin B on the IC Module?

 

Are you referring to the white trigger wire off the 6A box? it can be used to drive a tach but if you ground it the box won't fire. Your factory tach is driven by the PCM as Fred mentioned.