I have a 90 integra with a obd0 b16 and im gettin a code 21 from the ecu? car runs like absolute ****... ive never heard of a 21 from an obd0? any help??

 

Code 21 is ur Vtec solenoid.... Search, read the FAQS theres tons of info on this but i'll start ya in the right direction... First, is this a swap? If not when did u get the code? if it's a swap make sure u wired it up right. Also, u can manually check the solenoid by giving it 12V from the battery, u should hear a loud click.