Code 1215 after replacing head

[joonsup]

Yesterday my friend replaced the head on my m20 and after putting everything back together (ran out of light near the end), I fired the car up and it was idling rough at around 500rpm and sounded/felt like it was about to cut off. Looked up the code as AFM/Volume sensor and did a search to get some ideas on what it may be. But I couldnt find anything on the cause of the engine code after replacing the head.

Any suggestions on what to check for? My friend is coming back tomorrow morning but I thought that I would gather some information on where to start. Thank you

[Asbradley21]

check vacuum hoses.

[Fidhle007]

You forgot to connect something.

[joonsup]

ok here's an update. my friend disconnected and reconnected the battery and it idled smoothly at about 700 rpm after he put a different afm on temporarily w/out the airbox. Then we put back on my afm and it idled smoothly. Double checked the connections and made sure the hoses were on properly.

Then as we were in the process of bleeding the coolant while the engine was running idle, it felt as though the engine was "lunging" a little..., threw a check engine light. code showed it as 1222 (lamda control 1). My friend said it was the oxygen sensor.

When the a/c is on it idles fine w/out any problems but as soon as your idling after you turn the a/c off, it idles a little rough. Before I order a new oxygen sensor, any other suggestions on what to check for? My friend said to let the ecu adapt and replace the oxygen sensor. Any tips/insights would be greatly appreciated. Thank you

[joonsup]

so i swapped afm with my friend's e30 and nothing changed. i was going to try using his ICV but the connections/joints on his ICV going into the intake manifold looks different than mine. Mine is a T shaped whereas his is not. Still getting the 1222 code. Any help would be appreciated. This is getting frustrating

[joonsup]

no other suggestions?

[joonsup]

update: turns out my valves were too tight. my friend adjusted the valves while the head was outside the car and I guess that's something you're not supposed to do. My other friend readjusted the valves and now the car idles perfectly and it also gave me more torque.