If I have a fuel delivery issue, why would the OBDII scanner indicate a Code P0300, random cylinder misfire and not indicate a fuel delivery trouble code?
I spent all afternoon checking out various sensors and components according to my Haynes service manual. I checked the coolant temperature sensor, intake air sensor, crankshaft position sensor, MAP sensor, MAF sensor, EGR valve, and camshaft position sensor. Also checked the coil for cracks and found nothing wrong with it. When the engine runs poorly, it acts like a vacuum leak but I can find no vacuum lines or hoses on this engine to check. Everything on this engine (4.3 Vortec V6 with CMFI injection system) seems to be either electrically or electronically operated.
Every thing checked out fine according to the manual except for some erratic readings from the camshaft position sensor. Could a camshaft position sensor cause a code P0300 Random Cylinder Ignition misfire, and be an intermittent problem? Could this cause the engine to run rich also?
A few months back I replaced the distributor cap, rotor, wires, spark plugs and also the fuel filter all at the same time but none of this helped the problem. I'm running out of things to check... What else could I check that could cause intermittent problems with random ignition misfire and random running excessively rich? Are there any TSB's or other known problems on the 2000 AstroVan for problems like this?