Well the car is a 91 Z-28 w/ a 305 TPI 5 Speed . I am having a code 43 and the car is running poorly.............. So the thing is I have changed the knock sensor , the wire to the knock sensor from ecm , The ecm and chip, and have done a full tune up. Also checked for exhaust leaks and other bad wiring and I cant Hear
any noise coming from the engine or around it. So any ideas would greatly be apriceated .........Thanks

 

Indo,

Welcome Aboard!

Have you tried to analyze/inspect the HEI module wiring and connectors? The ESC should be built into the ECM on a '91, so the communication for timing advance is directly from the ECM to the distributor. Check the large flat Weatherpak connector from the distributor for connections, damage, or corrosion. You may also want to remove the distributor cap and rotor to inspect the connections at the HEI module itself. Especially watch for pinched, burned, or otherwise grounded wires.

 

Checked it all out all looks fine to me , but to you think it is worth a chance to change the HEI . Forgot to add it has 2 mechanics stumped.

 

Exactly what was involved in your "full tune up"? That is, what was replaced, cleaned, tested, or adjusted?

 

The spark plugs, wires, distributer cap and rotor, coil pack, belt, and most changable fluids and timing was also checked it is 6 degrees....................air filter and pcv valve were changed 2 months before this