my (haines) manual tells very little about tune up on my 89 240. B230F it has an air mass meter measuring the air intake , and there is a air control valve underneath the intake manifold. in the book I have it shows the air fuel mix being adjusted by a screw on the air mass meter , but mine has no such adjustment. I just finished rebuilding the engine. new pistons etc. etc. etc., the works.. it is in fine shape , mechanically, but still it failed the emmisions test. there is an switch on the on the throttle body and it seems to influence the air valve. I adjusted it a little to make sure it is closed and that just made the car fluctuate at idle. I would appreciate it if anyone can point me in the direction of any good info on the subject, or fill me in on how the system works. what can I check with a meter? or a scope? is there a screw somewhere to adjust airflow or something? also I have heard about reading the fault codes, and would like to learn more about how they work. I can and will have my experienced volvo mechanic look at The car , he is great. Still , I like to do almost all my own work on my 122 , 244 and 245 and we have a bunch more volvos in the family, so it would be nice to learn a little more... thanks, Phil
