I have an 02 saturn vue 3.0L that has a constant cylinder 1 and 3 misfire. It was brought to me by another mechanic because he has replaced the following, spark plugs, coil packs, intake and gaskets, injectors, computer, o2 sensors, fuel filter, crank sensor, and the misfire still presists in the same 2 cylinders. The compression in those cyliders are good I checked that out but im lacking conclusions on what the problem may be. It runs fine until the engine light starts flashing then it misfires. Any suggestions?
Up into 2002 those 3.0 v6 engine's had issue's with there timing belt tenisor's they redesigned them you can tell which one it has. The old design just has one pulley down by the lower left side facing the engine. The new design they moved the tensioner to the middle top of the engine and it has the idler and the tenisoner pulley on the same bracket.I would inspect the timing belt to see if it jumped time. Also if it has a aftermarket alarm that could be interfering with the ignition pluses from emi. There is a bulletin on that.I would also make sure you have spark to those cylinder's and injector pulse from the ecm use a noid light that way you know your getting power and the ecm pulse. Let me know what you find.