My Volvo doesn't fire quick it cracks for a short time first maybe I'm just being picky? And also the mass air flow sensor (air mass meter) has a screw on top what does it do somebody please tell me

 

The screw on top (1983-84 aluminum body AMM only if my memory serves me correctly) is a idle mixture adjustment only. (if it's on a black plastic body for a later year 1985? it's still the same thing) There is no stop on the adjustment either way, The screw turns a s shaped piece of metal that turns a rheostat. When you get to the end of the travel in the rheostat it just slips and feels the same. To be honest using an exhaust gas analyzer back then very few of those actually did anything as far as idle mixture, and even then by not very much.

A 3x year old Volvo fuel injection system could easily have partially clogged injectors or if you have a cold start injector that may not be working correctly. Or may have carbon build up on the back of the intake valves that absorbs the initial injector spray and prevents the car from starting instantly. As long as it still starts reliably, save your money for something to drive in the future. If you want to spend money - buy some Techron gas additive. Volvo actually recommended it back then to help with injector problems.

 

does the engine start and idle? if so don't worry be happy! you don't say your location what is the ambient temperature?

 

I found out it's the coil starting to slow down