I have a 1980 GL 240 series volvo with a higher mileage ( odometer crashed about last month at 264.000 kilometers )
Earlier I was having problems with the car "cutting out" until we found the injectors were loose, and once tightened ran fine.RAn for quite a while and then it started intermittently running rough again, but not cutting out.
When idling would run fine then backfire loudly-run fine then backfire again.etc. or would cut out when driving.
So about a month ago we changed the spark plugs and wires,( had anywhere from 50,000 to 75,000 "Klicks"on them) checked the distributor cap which looks fine. and it once again purred like a kitten. Then it started cutting out once in a while, which I thought was possibly water /ice in the line, as it had been quite cold( minus-15* F)
so put gas line antifreeze in, and once again it purred like a kitten.
Now if I don't keep putting either a tiny bit of seafoam or gas line antifreeze in it, say every 3rd tank, it starts acting up.
I have used different gas stations, and this has been over a month, so I can't say that it is a tank of bad gas..
I am wondering if maybe the oxygen sensor or fuel mixture is "off" ???
was told by one person the oxygen sensor is in the tail pipe / muffler system. The pipe before the muffler has a slight crack in it, and "it is in line to be fixed". No idea if that might cause a problem or not..
I have no idea how to even find the oxygen sensor or anything about the fuel mixture problem.
Appreciate any thoughts..
Thanks!