Replaced the Distributor, Coil & Main Relay in my 1995 Honda Accord 4 door LX. Now the Check Engine light is illuminated and the D4 light begins to flash shortly after start up.. Grr. Have checked and everything is plugged in whats the problem ? $300 spent and now a problem and issue I didn't have before...

D4 code-14 means the ECU is not responding to the TCU. The CEL light should be on solid which indicates the ECU computer is not functional. You can confirm that by shorting the SCS plug. A running ECU should output the codes on CEL or turn off CEL if no code is stored.

Two common causes of ECU failures are: 1) bad capacitors, and 2) faulty barometer inside the ECU. Capacitors replacement is quite easy to do but not the faulty barometer. Honda uses a custom barometer by Motorola which has gone out of business. The Motorola barometer was not designed to last 20 year. Getting an identical used ECU from junk yard likely will have the same issue. You may have to find a late model ECU for parts. D4 code-14 means the ECU is not responding to the TCU. The CEL light should be on solid which indicates the ECU computer is not functional. You can confirm that by shorting the SCS plug. A running ECU should output the codes on CEL or turn off CEL if no code is stored. Two common causes of ECU failures are: 1) bad capacitors, and 2) faulty barometer inside the ECU. Capacitors replacement is quite easy to do but not the faulty barometer. Honda uses a custom barometer by Motorola which has gone out of business. The Motorola barometer was not designed to last 20 year. Getting an identical used ECU from junk yard likely will have the same issue. You may have to find a late model ECU for parts.