Random Misfire with no CEL codes

[kmeister]

I have a 2000 Passat V6 with 140,000 miles. About a month ago i received these 3 codes P0300, P0301, and P0304. Car ran very rough so i pulled over waited a bot and then drove home to check codes and turn then off. Since then I have experienced several times that the CEL light will flicker - car runs rough (while I am driving down the road). The strange thing is that since the initial codes. I have not gotten a single CEL code after the car runs rough. I know there are the plugs and wires etc.... But wouldn't they just stop working and not cause intermittent issues. Any ideas or help would be appreciated.......

[afawal]

I have a 2000 Passat V6 with 140,000 miles. About a month ago i received these 3 codes P0300, P0301, and P0304. Car ran very rough so i pulled over waited a bot and then drove home to check codes and turn then off. Since then I have experienced several times that the CEL light will flicker - car runs rough (while I am driving down the road). The strange thing is that since the initial codes. I have not gotten a single CEL code after the car runs rough. I know there are the plugs and wires etc.... But wouldn't they just stop working and not cause intermittent issues. Any ideas or help would be appreciated.......

If the CEL is flickering, that means REALLY BAD misfiring. It takes quite a bit of misfiring before a CEL comes on believe it or not.

Do the plugs and wires. They wouldn't just stop working, the performance degrades over time. The plugs on the V6 are recommended to be changed every 40k miles if I remember correctly. That was the case on my V6 4-motion, but I don't know if the interval is longer for a 2wd version.

[koidragon1980]

if you find oil on the plugs or in the plug wells while doing the replacement, then you've got a leaking inner valve cover gasket that will need to be replaced as well.

it's a common issue with the v6 and will cause misfires and fouled plugs.

good thing is that the gaskets are cheap to get and the labor is one of the easier DIY jobs.

[doxster22]

Could also be a faulty ignition coil shorting to ground. Sometimes, when they are old they crack and do not always misfire but will occasionally cause misfires, especially when they get hot.