2008-2013 Cadillac CTS General Discussion Discussion, Putting in Cadillac CTS Second Generation Forum - 2008-2013; One follow up question. If I am changing the plugs myself (which due to my financial situation at the moment ...
One follow up question. If I am changing the plugs myself (which due to my financial situation at the moment is a real possibility) how difficult would it be to do the TB? I've heard that spark plug issues can muck up the TB and if I'm already under the good I may as well do it right. I just did the TB but I'm told that the unlit fuel in there can cause carbon deposits fast. I am moderately mechanically inclined and really want my ride back to its full potential. Since someone said that if I change one plug then change them all. If I'm changing the plugs after misfires should I just clean the TB?
Automobile(s): 2010 CTS Shooting Brake W/Performance package, 3.6 DI
It would never harm anything to clean the tb. If you don't then I wouldn't worry about it. Changing all plugs should help immensely. Now I haven't changed our plugs so I am not intimate with our engine. That being said, wear safety glasses and if our plugs are recessed then blow out the cavity before pulling plugs so any sand/dirt in there doesn't drop in. When installing new plugs check gap. Hand install and hand tighten to avoid cross threading. And put anti sieze on threads so they are easy to remove next time. Torque to specs.
Tinman, did everything like you said. It was cake. Nothing is in the way. You might want to take off the crossbar (I was advised by another forum member) because it will cut time in the end. The coil plug is a bit tricky but nothing too difficult, use a flathead as a wedge on it.
Now, when I took out the plug from the new coil I had installed two weeks earlier, I noticed that 2 week old plug had a LOT of carbon deposits on the lip. Is this from misfires?
Try a couple of tanks of premium and then check the plugs again. I'm not saying to permanently change to premium but a couple of tanks may give you a better indication of what could possibly be going awry.
Charcoal grey is too much fuel, not enough air, can be caused by a bad plug or one fouled by a bad coil. Listen to the putting noise while you are still using 87 octane. Could it be spark knock causing a slight stumble? If it is, premium fuel should slow the flame front and suppress the noise. If not, as CTEss said, continuing on premium fuel has no benefit, unless your car adjusts it's timing electronically by listening for high advance knocking.
If it is knocking, it's also possible the fuel in the tank is less than 87 octane = change gas stations.