1992 Eldo(RIP), 1975 LeSabre Cnvt, 2002 ETC ECS, 2009 CTS
I have been going through my 1992 Eldorado, it has the 4.9 liter, and have changed the fuel pump, fuel pressure regulator, cap & rotor, wires, plugs, several vacume hoses, and still the car runs a bit rough, the idle is unsteady and when you hit the gas the car vibrates. I also am getting horrible gas mileage and black soot on the tail pipe tips. I did the PFI power balance test. According to the service manual, as I select each injector I am able to turn it off to check that its working. The engine rpm is supposed to drop when I turn off the injector, except all of mine cause the engine rpm to raise??? Has anyone had this trouble and what is needed to correct it? Any ideas would be greatly appreciated!