I am having issues with my everyday driver as of late. I developed a misfire and replaced, plugs, coils, plug wires. Misfire persisted so we replaced, injectors, fuel rail. The misfire still was there and getting worse so we checked the engine mechanically for any burnt or bent valves and it checked out fine. We completed a compression test and all cylinders tested within 5 psi of each other. We finally replaced the ECU and Cam Sensor and the problem still is here. We do not know what else to do. I have narrowed down the misfire to cylinder one. The injector is not firing on this cylinder. I know this because when you unplug it there is no change in the engines behavior. As stated earlier, injectors are new, but i switched them out just to make sure it was a bad injector. I tested the lead and the voltage was appriopiate. Does any one have any suggestions.
If the spark plug isn’t firing then unplugging the injector won’t make any difference. Does this engine have a coolant passage in the manifold? Antifreeze or air leaking into the manifold could cause a miss and not effect compression.
The problem might with the driver in the computer for that injector. The injector will have voltage. But it’s the job of the driver in the computer to ground the injector at the appropriate time so that it fires.