Grounding problem
 

So I changed my coil packs and spark plugs the other day because of a misfire code. But now cranks but doesn't start. When I do crank it for the couple of seconds, smoke appears from under the intake tube. Could it be a grounding issue?

And....here we go.

You are probably experiencing a fuel delivery problem.

Did you label all the coil pack plugs before disconnecting? It's very easy to mixup the wiring harness plugs on some of the cylinders. This is a common mistake made when replacing coils or doing compression/leak down tests. Not sure about the smoke though, that should never happen. I would trace the source of that before continuing anything else. If you have a VQ35DE, the dipstick tube runs right under the intake plumbing. Another common mistake made is failure to fully insert the dipstick when checking oil levels. This can cause an oil leak with the potential for the oil to burn off on the exhaust manifold.
-Icer

icer5160 mentions a great point. I failed to seat my dipstick (actually a few times) and noticed oil consumption (loss in this case) with a burned smell. I was told I needed to replace the valve cover gaskets when in fact I simply needed to fully seat the dipstick.

HELP! same issue here, I did my clutch and charged my battery and car made a click but no start, after a little of fumbling around tried it again and smelled a little electrical. After that I never smelled it again, then I replaced the starter and went to start the car. Boom fire. Put it out with a fire hydrant after disconnecting the battery. Noticed already a ground on the drivers side of the motor right above the manifold was off. Got a new one and connected it. (The fire was clutch cable sleeve). Finally I tried it again and same thing. Still smoke but don’t see any messed up wires or anything else. Plz help!!!!!

Mine was also coming from right under the intake