Doing the timing chain job on a n14 engine. Had fun, it's my second one, and everything went much smoother this time. I get it back together, and it fires right up. Runs perfectly, then slight surging, then violent surging, like someone is revving the car, like blipping the throttle repetitively. Hmmm. I have had this happen before. its almost like the intake timing is jumping 20 degrees every second, and the car's computer is struggling to keep up (which is probably what is happening) Tear everything apart because of a code, 2B something 'unmetered air in intake manifold' something. Look for leaks, pressure test the intercooler pipes, no leaks. I swap out the VANOS solenoid and put everything back together. Fires right up, and slight surging, much better, tho. So i let it run, and this is the kicker, i use the scanner tool to reset the codes, and car immediately idles perfectly, smooth as elvis on velvet. Mel Torme smooth. So. Question: Did clearing the codes reset the cars adaptations, or was that just a coincidence? I wanted to hear what you guys thought...

 

the way i see it is resetting the codes is like telling the ECU to redo the math again. these codes/faults are stores in short term memory kinda thing.

adaptation is like face recognition. the ECU learn your driving habits and it is storing this info on another memory location like a long term memory kinda thing.

 

that is what I guessed, but I wanted to hear from some others with more experience than me...