I have a 1989 Honda civic with a factory d15b2, and it has a PGM-FI ‘91 integra intake on it. I’ve had an issue with it pinging. It’s really bad in cold starts and gets better as it warms up; best when the system switches to closed loop.

All work I’ve done since owning is: I’ve set the timing to 16 degrees, replaced coolant temp sensor, intake temp sensor, cleaned the IACV, checked for vacuum leaks, new fuel filter, plugs and ignition coil; and I’m sure other stuff I can’t remember.

what could be causing this issue? I doubt it’s carbon buildup, as the engine has low miles and was partially rebuilt. Seemingly got better after putting 93 in it over 89, but the stock engine should theoretically run on 87 no worries. I’m thinking it may be clogged injectors at this point, or possibly low fuel pressure.

I don’t have an afr gauge to see if it’s running lean, or a fuel pressure gauge but unless someone else has other ideas, that may be my next step.