Richness and running rough (Page 1/1) jjd2296 MAY 31, 11:04 AM Have a new 3.4 swap. Been running rough and rich. Gas smell in oil will start up then hunt for idle runs rich and hesitates and sounds off. Found wet and soot spark plugs. Did fuel rail test and it drops 5 psi after 2.5 min and 10 psi after 5 min. Have soot on the plenum. Pulled the top off and and then fuel rail. Found that the injector to their far left of the fuel rail in Under the plenum has soot on the inside and soot running up the fuel rail towards where the soot was on the plenum. Sign of a bad injector? Leaky or too much ch flow? See the black soot on the inside of the injector? And up the plenum But the other injectors are clean jjd2296 MAY 31, 04:14 PM Ok so I’ve tested the injectors by priming and clamping both feed and return lines. No leaks. So this must be either an injector flow issue or a spark issue?? Could it be a bad icm too? Gall757 MAY 31, 08:49 PM quote Originally posted by jjd2296: Ok so I’ve tested the injectors by priming and clamping both feed and return lines. No leaks. So this must be either an injector flow issue or a spark issue?? Could it be a bad icm too? Are you showing us soot on the outside of the upper plenum? That may tell you that the EGR tube is leaking, but nothing else. I think it's more likely that you have a bad sensor making the fuel rich. The 02 sensor or the CTS are possibilities.