Misfiring

Hello,

When your Malfunction Indicator Lamp (MIL) or "check engine" light illuminates, that means you have a Direct Trouble Code (DTC) present and there is something that is not working properly. However, when your MIL comes on and is flashing, that means you have a serious problem that must be dealt with immediately, or serious damage will occur to your vehicle. This is an A type misfire, not the B type which is run of mill. A type misfires occur when there are 250 misses out of 1000 engine rpm's and is classified as a "catalyst damaging event". You need to pull the DTC and get back to us us with what it is. Here is a link if you are unfamiliar with how to do this:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please get back to us with the DTC. We will be able to help you from there.

Thanks,
Alex
2CarPros

Hello again,

Okay, so you were able to pull DTC P0304. In the diagrams down below I have included the factory diagnostic troubleshooting guide for DTC P0304 for your vehicle. I would start by checking my Coil on Plug (COP), associated connector and wiring going to the connector, and my spark plug for cylinder #4.( Please go through this guide and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Hello again,

If you are suspecting that it is fuel related because it is only misfiring when there is a load put on the engine, than I would suggest starting by replacing your vehicle's fuel filter. I have included directions for how to do this in the diagrams down below. You will need to get a set of Ford fuel and air conditioning line dis-connectors at an auto parts store to do this. They are relatively inexpensive, around $10.00, but absolutely needed for the job. Also, if you do decide to get new fuel injectors, I would highly recommend that you stick with Original Equipment Manufacturer quality injectors or higher. This is where you do not want to skimp and get the cheap or cheaper injectors on Ebay. They absolutely do not perform as advertised and you may wind up doing serious damage to engine as a result. Go with Bosch, Sieman Deka, Denso, Ford Racing, etc. Please get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Hello again,

Good. Good. I only mentioned that because I also have a Mustang. Mine is a 1997 Ford Mustang GT. It is a custom build with many extras including a Vortech V1 supercharger producing 12 - 14 lbs of boost. Just to double check what lb. Injectors did you put on? Anything over 19 lbs. Will require a reflash of the PCM.

Thanks,
Alex
2CarPros

Hello again,

Okay, you might be starving your engine of fuel with those injectors. There is a specific formula for how to figure out what size fuel injectors your engine needs. It is called Brake Specific Fuel Consumption (BSFC) and for naturally aspirated vehicle's it is usually 0.50. So to figure the fuel injector size take your engines horsepower, in your vehicle's case 275 hp and multiply by BSFC which is 0.50 = 137.5. Then divide by the number of cylinders your vehicle has = 17.18. This is the lbs each injector needs to be at Wide Open Throttle. The next popular size up from 17.18 is 19lb. Fuel injectors. Ford Racing has great articles explaining all, of this in far greater detail. Check it out and let us know how things progress.

Thanks,
Alex
2CarPros

Hello again,

I believe they are 19 lb. injectors. Do they have yellow tops? Anyway this sounds to me like you could have a vacuum leak, more specifically I would guess the intake manifold. Here is a link below for you to go to explaining this in more detail. Please pay special attention to the intake manifold when you are going through this and get back to us with what you are able to find out, please.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Thanks,
Alex
2CarPros

Hello again,

Disregard my last reply. I'm so sorry, I thought you were a different customer all together. Yes, yellow top fuel injectors are 19 lbs. Fuel injectors. Everything else please disregard. How is everything coming along with the misfires?

Thanks,
Alex
2CarPros

Hello again,

Yes, these engines are super sensitive to any fluid that gets into the spark plugs holes will cause that cylinder to misfire. That is even the smallest amount of moisture will cause that. Take the coil and the spark plug out and make sure they are both 100% dry, up in the boot for the coil, and the cylinder will run like brand new again.

Thanks,
Alex
2CarPros

Hello again,

I also had a problem with number 4 cylinder on my Mustang. If the intake manifold is off even a little bit in that corner it will leak coolant out of the intake manifold gasket and it will get into the spark plug hole. Also double check the return heater hose and make sure that the clamp is secure where it clamps to the intake manifold. Double check that there isn't a coolant leak in the corner of the engine and get back to us with what you find out.

Thanks,
Alex
2CarPros