Ryan suggests the possibility the adapter may be the problem, but the failure rate for it is very low, so no way to know for certain without an extended test. I am going to install an old Memcal that was programmed for my previous turbocharged engine. This will eliminate the adapter. It isn't optimum, but the injector constant is correct for the 30# injectors so it is safe to run, within reason. Until I accumulate a bunch of miles, there is no way to know for certain. He stated the pulsing check engine light usually indicates an internal ECM communication failure. I need to find one or more 1990 compatible Memcals to be able to program without an adapter.😢