My EG w/GSR was engine codes 1, 21, and 43. I have double checked all my wiring to the ecu and all the parts came from the same car. Before motor was pulled I heard it run and no CELs I put it in and now I have them. It runs good at WOT and MID but off idle falls on its face. Thanks for the help.

 

what year is the engine obd1 also ?

 

OP, what ecu, harness, and intake manifold are you running?

 

1994 stock everything P72 ecu stock single butterfly intake

 

Have you properly reset the ECU to see whether all codes return?

 

Yes always get 21 43 first time for 1. Mash the throttle and everything's great vtec and all barely ease the throttle misses like crazy

 

did you wire the vtec sensor? no idea what model civic you have.
you say vtec is great, but it shouldnt be with code 21, might just be mistaking the gsr secondaries with vtec?

have you bothered following the service manual for the engine cels youre getting? if not just dld the manual thats ehat theyre for.