Volvo: failed smog, volvo 240 dl, mass air flow sensor

Question
my 1988 Volvo 240 DL failed smog today and the person there said it was running both very rich and with very high emissions. It also is shaking when it is idling and at higher rpms. Is there anything I could do at home or with minimal cost?

Answer
Jonah,
Well rich means the fuel mixture. If you have a H/C C/O tester hook it up and try adjusting the Mass air flow sensor. Look at the fuel regulator and see if at the vacuum hose there is a fuel leak. There should not be a fuel leak. Test the fuel pressure and make sure it is not to high. 42 PSI max. if fuel pressure is to high that will richen the mixture. Blocked air filters cause a car to run rich.
Shaking maybe a engine miss, check the plugs, cap, rotor, plug wires replace as needed. Check that all fuel injectors are firing.
If all that is good take a compression test see if you have a weak cylinder.