I just purchased an AP2 engine and put it into my 2001 s2000. I was told I would not have to change anything. That the swap was perfectly interchangeable. I did the swap and the car drove fine for about 200 miles. I then found a slight stutter in accel and the car once turned off did not want to crank. I roll started the car and drove it approx 5 miles and the valves started rattling and exhaust backfiring. I pulled over immediately and added half a quart of oil. Continued back to my house (another 3 or so miles) and made it to my driveway before it started backfiring and rattling again. Was wondering if it was that i needed a AP2 ECU or timing, junk engine? any advice given would be greatly appreciated. The new engine had 14k miles on it when purchased. Thanks

 

Figured out why it wouldn't start. The spade on the starter had slipped off.. I still have the rattle and planning to do a valve adjustment. Was going to see if there were any other ideas of the rattle before and even after I do this adj. The engine I installed has only 14k miles so thats why I am not sold it is valves completely. Any ideas will help. Thanks

 

Im fairly certain you should be using an AP2 ECU. Your AP1 ECU still thinks you redline at 9, which you arnt.
IIRC I saw a thread recently and it was stated you "MUST use an AP2 ECU if you swap from f20c to an f22c, many things changed that your AP1 ECU doesnt know."