Contour Enthusiasts Group Archives Forums General Troubleshooting RICH OR LEAN? (was: Anyone ever removed and cleaned fuel injectors?)

Believe me, I have looked and looked for vacuum leaks. I recently took apart the PCV and EGR plumbing just to check them (and replaced the PCV valve), to no avail. This is why I was becoming suspicious of the injectors: because (a) someone was just talking about them, and (b) I've checked almost everything else.

But now I am unsure again. I checked the plugs last night. It was my understanding that an engine with the right mixture is supposed to have tan spark plugs, whereas a lean one will have whitish plugs and a rich one will have dark sooty plugs... right? Well, despite the lean code, the plug color was rather dark. Brown on the insulator, near black on the metal rim (but not fluffy). All plugs the same, which shoots down my theory that maybe some cylinders were lean and others were too rich in compensation. These plugs almost (but not quite) look like it's running rich rather than lean. Which makes me think it's the oxygen sensors.

But I voltmetered them and was assured that the readings showed were working right. Also, running rich should rob mileage but not peak power, right? I've lost significant power (and a bit of mileage too).

I'm as baffled as ever. I don't know whether to buy oxygen sensors on speculation, buy a vacuum pump and try finding the leak by pumping out various hoses and see if air gets back in, or spend $400 for a good shop to find what's wrong.