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Where to begin.. fouled spark plug

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    I don’t really know where to start.. I’ll try to give as much detail as I can and I’ll answer any questions that I can. I’ve had my 07 tC for about 4 years. It’s always used some oil, but recently it’s started using more. About 1-1.5 quarts ever 150miles. Also, about 2 weeks ago it started running like a lawn mower.. felt like a misfire so I changed all the plugs 2-4 were all fine, but 1 was black and had oil on it. After changing plugs it ran fine for about a week, then the same thing happened again. Changed number 1 again and I’ve been good till today, it fouled again. Thought maybe it was the rings because occasionally I have a little puff of smoke (not much, and not very often) checked the compression and got 190,180,185 and 180. Also noticed some oil around the valve cover on the passenger side. Gonna change that gasket tomorrow. Any ideas on what’s going on?
    thecodyset wrote:
    I don’t really know where to start.. I’ll try to give as much detail as I can and I’ll answer any questions that I can. I’ve had my 07 tC for about 4 years. It’s always used some oil, but recently it’s started using more. About 1-1.5 quarts ever 150miles. Also, about 2 weeks ago it started running like a lawn mower.. felt like a misfire so I changed all the plugs 2-4 were all fine, but 1 was black and had oil on it. After changing plugs it ran fine for about a week, then the same thing happened again. Changed number 1 again and I’ve been good till today, it fouled again. Thought maybe it was the rings because occasionally I have a little puff of smoke (not much, and not very often) checked the compression and got 190,180,185 and 180. Also noticed some oil around the valve cover on the passenger side. Gonna change that gasket tomorrow. Any ideas on what’s going on?


    hey good to see you again! ya it sucks, what's going on with your engine. The only thing that comes to mind is the infamous 07-09 piston ring issue/oil consumption. Post a picture up of the fouled spark plug, especially the center electrode.

    The solution? worst case is you need the pistons replaced. The other solutions would be PCV valve, if that is dirty you can end up consuming oil since the pressure isn't relieved through the pcv system. Another issue I've seen on my own 06 is the oil itself. A lot of changes have been made to all motor oil over the past couple of years. We've gone from API SN to SN+. With that the characteristics of the oil has also changed. One being the NOACK/Volatility. When I was using an oil with that number (a percentage) over 13% I noticed my oil level going down. Turns out the oil was vaporizing at a higher rate. The tC is a hot running engine, any trip in the winter you'll see how fast the heater, heats up! so.. it could be that your oil has changed it's specs, even if it's the same name! What oil brand + model name are you using? what oil weight?

    so yes there are a couple of simple alternatives.. another being a chemical soak of the combustion chambers. you pour this chemical (teaspoons) into the spark plug hole, let it soak, then somehow remove it. I've heard of it on the oil forum, bob is the oil guy forum. I think GM was using it for the Direct Injection engines. or something like that.

    let me know about your oil..
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