I have a 2000 Nissan Frontier that reports a #2 cylinder misfire and knock sensor codes. I replaced the plugs today and checked the wires. Just had the distributor replaced two weeks ago. After changing plugs, the truck runs very poorly and i have smoke from under the truck, coming from the exhaust system. ideas?

SOURCE: multiple cylinder misfires

cross the wire, probably the firing order problem.

Did you change the distributor cap, sometimes the distributor cap inside cracked, you won't see it, take off the distributor cap, but you have to remember the wires' order, lightly drop the distributor cap see if you can hear the cracking noise.

Or during the dark night, get a dark place, start your engine,see if there is spark out, fix that, maybe your car will run better.

When I had my Union 76 service station, I have solved several cases like thiat.

I had a big Sun electronic scope from 1973 to 1984, during that time, something I could't ping point where the problem was, therfore I used many experience, maybe I am wrong, but you can try it, I like to try everything.

Hope this ccan help you, good luck.

Frank

SOURCE: would a cracked exhaust manifold on a 2002 nissan

yes it could.... check the oil for traces of foaming...that would indicate water leaking via a crack.
Also check for oil in the water reservoir.... sign of cracked head also...

SOURCE: misfire cylinders 1-3 how can I clean them? do I

Hi, As you know that in engine repairs only a well experienced technician can do it because it is the heart of the car. If your engine is misfires than the piston is almosted ceased. Kindly don't hesitate to spend money, it is a very difficult job.
Remember one thing service your car only in a authorised center for a better engine performance and long life.
Thank you.

SOURCE: 2000 nissan frontier knock sensor code & distributor

no but the knock sensor does send a signal the ecm and it will ****** or advance the distributor timing