I was out in the wife's 1980 244 running errands when I suddenly noticed the engine was not responding well to acceleration. It would hesitate/buck. I stopped and I checked the oil. I looked the engine compartment over and saw nothing out of line - plenty of coolant, etc. I even checked for vapor lock. Finding nothing I decided to try and get home again. Once up to a constant speed, things smoothed out a bit and I was able to get back ok.

So the wife is in a lather. I let the thing cool down (it seemed quite hot but I had been driving around for a while and was on the way back home and, after all, it is getting hotter outside - no real signs of overheat - nothing on gauges, etc - some vapor came out from the oil filler cap when opened but no sign of sludge or water in the oil.

So I pulled the plugs since it was easy to do. All save #4 were just fine. As you can see here (drive.google.com/file/d/1XHOddQrCbaotIzPYEnoy0_twOsAdDGXa/view?usp=sharing) (BTW I could not get this to upload to the gallery), #4 did not look good. I have personally never seen that on a Volvo. Seen it plenty on VW bugs in my earlier life and it rarely meant anything good. Amazingly, I still have my hand-held compression tester - unused at all since VW days. I was able to get decent readings with it across all cylinders - pretty much a constant 150. I have no idea what it should be on the 1980 but the fact that there was no variance to speak of seems a good sign to me.

In doing the compression test, I removed the cap and it and the rotor seem fine to me. I also checked the flame trap and it was fine too. I haven't a gasket right now, so not planning to check the valve clearances. But I doubt that would add much info.

So this leaves me wondering. The plug seemed wet as well as fouled to hell. So I presume it is getting fuel. But too much? The rest of the plugs looked great and given the car got us home it doesn't seem like a general fuel system issue like filter or pump. Perhaps a sticky #4 injector? Given that the compression is consistent, I don't think there is oil leaking past the rings or valves. But this is not proof of that.

This morning, after putting all back together, I misted water over the #4 intake and exhaust gasket areas with a spray pump bottle while the car idled. I MAY have noticed a SLIGHT stumble in the idle when spraying the intake area. But the idle on this car as never been smooth as silk. So I could be totally wrong. I also note that the fuel injector is in the same area and got misted. So perhaps that?

I took the car for a test drive around the neighborhood - up/down hills and flats. Seemed perfectly fine to me. So after it cools again I will check #4 for signs of fouling from that.

One thing that has changed is that I have been running 10-30 in this car whereas I have generally always used 10-40. I asked the wife to get oil one time while at Costco. Told her I wanted 10-40 but she came home with 10-30. I figured no big deal and started running it - so far, only in in this 1980 though. I wonder...

So I ought to ask the master! Your thoughts please? Thanks