joshkdemoss

Hi! Im having trouble with a cylinder 8 misfire. I have an 06 Mustang Gt 4.6L 3V. I'm pretty familiar with cars as ive been a technician at a lube shop before but then again im not mechanic. So I was driving down the highway when a flashing check engine light came on and my car began than have a lopping noise kinda like I had a performance cam installed but I dont. Just some exhaust work like pypes high flow cats and flowmaster mufflers. I pulled over and looked under the hood for any signs of severe damage and didnt see any. I decided to take my chances and drive to autozone since the light stopped flashing and the scanner showed a cylinder 8 misfire. So I bought 8 spark plugs and boots and 1 coil pack(due to lack of funds). Well when I got home and tooke my coil pack out I found moisture of some sort pooled up where my plug is. Couldnt tell if it was oil or not by the way. So I checked the coolant for oil and the oil for coolant and there was none. So I decided to just change the spark plug, coil and boot for cylinder 8 hoping to save money. After some research I found that cylinder 8 was at the top right of my motor. Anyway I replaced them with out breaking the plug(thank god) and my car is still running rough and pulling a cylinder 8 misfire code after being reset. So I was hoping for some help. Btw my car is only at 85,000 miles. Any help would be appreciated! THANK YOU! Also sorry for my life story.

Simon1

List the mods you have done to your car.

joshkdemoss

The only mods I have to the car is pypes high flow catalytic converters and flowmaster mufflers. I also have a subwoofer system but thats not a mechanical mod.

joshkdemoss

I also normally run the high octane gas at the gas station. Normally 91 octane. I dont know if that makes a difference.

drewsky

Could be a clogged injector possibly... Like the answer to most simple problems on these 4.6 3V's. Clean the throttle body and run some injector cleaner through it then go from there. It sounds repetitive but it comes out to be a huge solution on these stangs

You can also check all the injectors are clear. Possibly bad gas? It's a good idea after 85k. You can change the fuel filter for peace of mind

Derf00

When was the last time the fuel filter was replaced? Kind of after the fact at this point but if it hasn't been changed in a long time it could've clogged an injector.

Also, I noticed you mentioned moisture under the #8 coil boot? Did you recently get heavy rain or water in the engine compartment?

I'd do a compression test on that cylinder just to be sure the cylinder is ok.

By the way, break up your responses. Solid text paragraphs make things hard to read. I missed the moisture part the first two times I read your OP.

ThaiCobra

Are you sure you addressed the right cylinder?

It's VERY easy to mix up which number cylinder is which.

I had a similar issue one year ago. It was the coil. soon as I swapped out the coil everything went back to normal.

joshkdemoss

Honestly I wasnt even aware that it had an inline fuel filter till it was mentioned.

Sorry for not breaking up the paragraphs.

I really hope that my fuel injector isnt clogged because ive had that bg fuel induction service done twice but im going to change the fuel filter tonight and check the fuel injector as well. Thanks for the help guys! Ill keep every one updated

Simon1

Before I clean anything I would switch coils from #8 to somewhere else. See if the problem follows.

If that didn't change anything, switch it back, trade spark plugs.

What codes is it throwing?

It's been awhile since I studied up on it, but is there any possible way the hi-flow cats could be throwing off the rear O2 sensors?