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Re: Black, sooty spark plugs. 900 Turbo Posted by RS [Email] ![]() ![]() ![]() In Reply to: Black, sooty spark plugs. 900 Turbo, Eric B, Wed, 11 Jul 2001 09:22:29 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Sootiness indicates that you're running rich.
First, drive it a while with the new tuneup and see how it fares under your driving style. I'm assuming that you don't get a lot of blue smoke while you're driving. If you still have sooty spark plugs then it might be any one of a few things.
My guesses are:
Running a lot of short trips.
Bad NTC (Negative temperature Coefficient) sensor - this indicates engine temperature to the fuel system. It may be incorrectly indicating low temperature when it's actually at normal temp.
or
Bad fuel pressure regulator either having a weak spring letting fuel to the rail at too high a pressure or dumping fuel through a weep in the diaphragm.
or
Bad O2 sensor.
or
Thermostat stuck open.
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