I have a 1990 Bronco 2 2.9L with 140,000 on it. Took it to emissions and it passed everything except the NOX, got 12.24 and the standard reading it says is 2.40, so way over. Came back and pulled codes and got a code 44 " problems in the thermactor air control system".
Looked it up in the manual and didn't quite understand where it was located on the engine or what the components looked like. Pulled diagrahams off autozone but they don't match.
Checked all the vacum hoses and they all seemed fine, except the PCV valve hose had a crack at the connection point, replaced that and PCV valve but was not sure if just that was enough to cause such high readings.
Any more ideas thank you in advance.
Also checked timing which is fine, put new plugs, wires, air filter, cap and rotor on it.