We'll I cracked a sleeve on my boosted Ls vtec the other day with only 2500 miles on the freshly rebuilt to stock motor. So I picked up the same bottom end (b18a) but with 70k miles on it. When I went to start it up for the first time, it started and then stalled. After starting it up a couple of times it would idle, but show 11 on my aem wideband. And the idle was very "low" and rough. What could be causing this?

 

retune

 

How come.I would need a new tune if the compression ratio is the same and the displacment is the same. It is the same exact motor that is on.the "tune" except the bottom end has 70k on it

 

Double check timing and also valve clearance. I switched heads on my block once and forgot to redo valve clearance and had similar problems.

 

Retune, no 2 engines are identical.

 

^agree. If ur other motor had 100k and the new bottom end has 70k chances are ccompression wont be the exact same so re tune it