Well lately I have had an issue with my '90 F150 4.9 I6 where it would sputter under load. I thought that is was just a bad tank of gas but the problem continued to get worse after a few tanks so I started checking a few things and this is a picture of the #3 spark plug. Sorry the quality is not the best but it was taken with my phone. It was covered with a build up of white deposits. What causes this? i am pretty sure that is what caused my sputtering problem but I want to find out why the plug fouled in the first place. Thanks.
Only that cylinder? Could be valve seals on that cylinder. Fuel injector stuck,if yours has individual injectors. If all the plugs look like that check your air filter and PCV system. Does it use a lot of oil?-gas? Oil is most likely clogged PCV or valve seals. Gas is clogged air filter or bad MAP sensor. Wouldn't hurt to have a compression test done,either!
Well the #1,2, and 4 plugs look fine. I ran out of daylight so I havent pulled #5 and 6 yet. Ill let ya know what I find when I get to it. I just replaced the pcv valve a few weeks ago and I havent noticed any excessive use of any fluid, it has actually been running leaner and leaner I think because my gas mileage has gone up and up.
Yeah, that looks like it. It just seems weird that oil causes that. I would think the oil would just burn.
Been fighting the same problem with my car for a while now. Seems to be the gas causing it. All the gas around here has ethanol in it now.
Ethanol will not cause those deposits. If anything Ethanol will help prevent them. The cause is the chemicals (modifiers) that are added to make the gasoline stable and burn better. Octane additives, cleaning agents and anticorrosives are the likely suspects.
