Hey folks

my parents 2000 S80 2.9 has developed a random misfire. At first the CEL was not on, then when it came on today i took it right in to a parts store who said the scanner connected but the car says no stored codes. I did the spark plugs this morning with the engine cold since I didn't know when they were last done and found bosch 4 electrode plugs. They had some wear and 2 had oil in the tubes, but there were no obvious issues. I repalced them with single motorcraft platinums gapped to .030. I also just added injector cleaner to a full tank of gas. I'm just frustrated with the CEL being on and the car still saying no codes. I'm about ready to try 1 good new coil and swap it around, and also take the car back in a couple days to have to code read somewhere else as well. Just curious if anyone has any other ideas or has seen this before. The car has 184k, and was in a front end accident last winter. I replaced everything from the grill to the engine front (rad, condenser, fan, repaired a lot of severed wires, voltage regulator) and the car has run fine since then but has gradually developed this symptom over the last couple week and now it pretty much always there but it is random/uneven. It seems to be there above idle but the only place it's quite obvious is at idle.

 

Have you tested your camshaft and crankshaft position sensors?

 

thanks for the suggestion, I will keep it in mind. I saw that when going through threads (it's a common failure point on my Mark VIII as well strangely enough) I will be going back today, but it seems the fuel injector cleaner may have done the trick. They say the light is out and it's running much better. I will see if there's any sign/sound of a misfire. In this case I ran a can of seafoam in a full tank of gas.