Originally Posted By: gr8gatzby
Acquired an eBay '90 740 NA one month ago for $1k on eBay. B230F engine with auto and 180k on the clock. No leaks but ran like [censored] and with hole in exhaust sounded great. Installed stock exhaust, plugs, wires, O2 sensor, K&N, and one AutoRX treatment. Runs 1000% better now but fuel economy is between 16-18mpg with 50/50 city/hwy. There's also a persistent and audible tick coming from the engine at a rate of perhaps 12 ticks/knocks per second. Is this normal?
I thought it had the 16 valve engine? If so, that is a B234F (16 valve), not a B230F which is the 8 valve engine. You might want to double check that all of the parts that you installed are correct for a B234F. I know that the exhaust system for a 16v has some differences and they use the Bosch fuel injection while some 8 valve cars used the Regina/Bendix fuel injection. That system uses a different oxygen sensor which will physically fit a car with Bosch injection but is incorrect.
I would also replace the cap and rotor in case you haven't already with a quality replacement that has brass contacts.
Andrew S.