I have a 2001 expedition 4.6L V8 recently it ejected a spark plug (3rd one back on left if facing vehicle) I used a cylinder repair kit (helicoil) as the internal threads were damaged and was able to fix it. However now the vehicle shakes at idle and on takeoff it's not as noticeable once you get rolling. Is it possible it threw off the timing? Possible vacuum leak? I'm at a complete loss. I need some help!
Thanks all,
Steve
All4lillib@yahoo.com

 

Not sure on the answer, but I am positive that it did not through off the timing.

 

With the engine idling, disconect the wire to the COP on the cylinder you repaired, see if it makes any difference in the idle. If there's no difference try replacing the spark plug in that cylinder. If there is still no differnce with the new plug swap the coil with another cylinder and see if the miss moves with the coil. If it does change the COP.

 

With risk of sounding stupid what's the COP??? Also is there any risk in driving it as it is? I need to get it to my garage about 30 miles away.

 

COP is the coil on plug as opposed to coil packs. It is the black thing with the long rubber boot that goes in on top of the spark plug. There is a wire connecting to it. Mike has given you troubleshooting steps to determine if your coil is bad.

 

Ok problem solved!!! Originally it ejected the #2 spark plug I had replaced the plug after repairing the threads. Not a change. Next I replaced the COP as advised above still no change!!!! The #6 coil failed and after replacing the COP on that cylinder as well as the plugs the beast is back!!!!! Thank you to all who helped me in this very frustrating endeavor!
Steve

 

super glad it is running better

BUT....Sadly, the helicoil repair is not going to last...many have gone before you trying them, & they end up spitting it out again.

what seems to be the more proven durable repair is time serts...
http://www.timesert.com/html/triton_repair2.html