I have a 91 Z28 350 TPI. Its having some running issues as far as accelerating to a higher speed and hesitating and occasionally the Check Engine light will come on. I've changed the fuel pump, fuel filter, new distributor, new plugs, new wires, cut the cats off and got new exhaust. I've tried to time it but I would always line up the mark right on zero, then unplug my battery and plug up my computer again, but I'm afraid i might be timing it wrong and that something else might be wrong as well.

Let me know what I might need to do to get it running smooth.

 

https://www.thirdgen.org/settingtiming
You time the engine's base timing with the EST connector unhooked. The ECU electronically advances the timing, and you will not be able to correctly time it with the EST connector hooked up.
The EST connector is right here-------->


Time to 6* BTDC (Factory Spec), not 0* as you specified.

 

Pull the SES codes - grab a paperclip and read: https://www.thirdgen.org/service-eng...ht-error-codes

 

Ok, so I did the timing this morning and its perfect. What you said really worked, thanks. But it has a miss in it somewhere..