I have an ECB, great smoker to get some skills on. But it needs mods. I wonder what your temps were. The therm on the ECB is notorious for being LOUSY. I would suggest adding at least one therm to the lid here is a pic of mine with a therm i picked up a Home Depot for $6 if i remember correctly .
. A second is not bad for the side.
I smoke whole chicken for about 5 hours, can take up to 6 depending on a few things. I like to keep my smoker at about 225 for whole chicken.
Do you have electronic meat thermometer? You can get wirelessones, but I have yet to find one that works well. So i just get simple Taylor therm for $12 at Lowes and just walk to the smoker to check my temps. Or look out the patio window.
With keeping temp at a consistent 225 ish and get internal temp of the chicken of 180 in 5-6 hours. We like apple and hickory or apple and cherry for the wood.
Here are a couple of pics.
Pic on left is whole chicken on my ECB the one on the right is from my Master Built Gas smoker. I like the gas smoker better since it keeps a more consistent temp. But the ECB can do it just takes some work and USE the mods recommended in many forums here.