Is there a way to test the efficiency of the coil packs. Just replaced all plugs and wires few months ago. Im consuming appox 6-8 miles per gallon. Any ideas

 

Coil packs are cheap; I would have replaced them as a matter of course when you had the heads/intake manifolds off. However, I wouldn't expect them to have that much impact on your mpg unless you were getting significant misfires.

 

Were the sparkplugs correctly gapped?
I know most people on the forum say not to gap brand new spark plugs but all 8 of my brand-new-out-the-box NGK Iridium IX sparkplugs ranged from .035" to .050" gaps.

 

Agree with both of the previous posters...not really sure why you think the coil packs would be causing poor fuel mileage...unless you are getting a rough running condition or misfires. But, if the engine is idling properly and has smooth acceleration...I believe you have to look elsewhere.

And, who the heck is giving advice about "NOT" gapping plugs...that's just crazy. Always check and properly gap plugs...they could have been damage in transit or by the parts counter guy.

Fuel quality or dirty air filter would be my first diagnostic thoughts. Picked up a bad tank of premium in my car once, mileage went from decent...to absolutely terrible. Took two tanks to finally clear it out.

Hate to sound like a broken record, when it comes to fuel quality...but from my experiences...it is one of the biggest issues facing motorist these days. Anymore, the last thing I do is start throwing parts at a rough running engine (with no codes), since it usually ends up being fuel related.

Brian.