99 5.4L v8

Started the truck today and there was a strange vibration coming from the engine. Not the mounts or anything but a constant hesistant rumble. It stayed and was more apparent upon acceleration. After I ran an errand the Check Engine light came on, and the sound seemed to fade (Im sure thats temporary)

In the past few weeks I have noticed a the same slight rumble when I began to accelerate from a stand still for the first few feet of movement.

My friend thinks its a misfire or bad cylinder. Any comments, thanks guys.

 

Have you had the codes pulled?

The codes will point you in the right direction. This could be any number of things ranging from plugs/cops to EGR/DPFE issues. Get the codes pulled at Autozone and post them. We can help better from there.

 

Agreed. Have the PCM scanned for codes. It might be a bad Coilpack, but could be many other things too.

 

Just came back from AZone, it gave a code 308 - 8th cyl misfire
The dude just suggested that I change all the plugs back to motorcraft. I put some other brand (cant remember) in there 6mos ago. I have 2 weddings this weekend, can I drive on this until Monday or Tuesday? What could happen?

Thanks.

 

If you have the time, definately put motorcraft plugs in, it cant be healthy to drive it like that.

 

How many miles do you have on it? The coil pack could be bad as well. I use Autolite plugs and have been very happy with them Yours would be ap103's I believe. As for damage, it could cause damage in the cylinder that isn't firing. If the CEL is blinking they recommend that you do not even drive it at all.