Hello I have a 2008 Crown Victoria Police Interceptor , Right Under 110,000 miles . Car always runs good but ive been seeming to have an issue with the engine light. The first time my light came on i took it to autozone to have it read . P0305 is the code and it recommended to change the ignition coil. . I changed all my spark plugs and the ignition coil for #5 and the connector for #5. My engine light will be off for a couple days or weeks then come on for a day or two . I noticed when i was at a red light the engine light randomly started blinking for 30 seconds or so and then shut off and stayed off . Any advice on what may be going on ? Ive had it read about 10 times sense and the only code that comes back is PO305 . Oh and when it blinks i can feel a slight diffrence in my car. A little shaky but it stopped within a couple seconds.
A flashing Check Engine light means a major misfire is occurring and serious damage can be done.
Don’t drive the vehicle until it can be determined what’s causing the major misfire.
Tester
Cylinder 5 misfire. The approach usually recommended is to swap stuff around between 5 and another working cylinder. If problem follows the swap to the other cylinder, you know what part it the problem.
- spark plugs
- ignition coils
- fuel injectors
- wires
If that doesn’t work, next step would probably be to do a compression measurement on all cylinders.
If the reason for the misfire is the fuel/air mixture isn’t igniting, that will send raw fuel into the cat, which can quickly damage it. That’s why when the CEL in flashing you got to take it seriously. Cat replacement is quite expensive.
you’ve already taken some good steps by replacing those parts mentioned
is #5 plug oil soaked?
use a noid lite kit to see if all injectors are being pulsed correctly
perform an injector balance test
perform a dry and wet compression test on all 8 cylinders
there’s considerably more testing to do, before guessing and throwing more money at the problem, in my opinion