I have been getting a P0301 fault code this weekend. Mostly triggered when I am stepping on the gas when getting on the highway asking for power. I just put in a new engine (long block), new plugs (Bosch Platinum +4) and new wires (Magnecor).
The car has been running well since the new engine (I only have 600 miles on it) but I am in the dark on this and am just looking for any other thoughts.

 

Did you check your wires? Sometimes even a new wire can leak. Try swapping it out with an old wire, and it might fix it. Did you use the old coil pack or a new one? It might be shorting out too... Just some ideas..

 

I was told that a bad coil pack will show a misfire in two cylinders and not just one.
I need to try to swap wires to see if the fault code follows the moved wire or stays with the cylinder.

 

Have you removed the plug and checked to make sure you didn't crack the porcelen?
Was this a new long block or used, did it come with head? If so you might have a carbon build up or a warn cam lobe.

 

Plugs look good.
The new engine was a new (remanufactured) long block that came with the heads.
I brought the truck back to my mechanic that did the engine install. He told me that there was multiple misfire codes on a number of cylinders. The truck runs well but hesitates (and misfires) when you step on the gas...like getting on the highway or trying to accellerate up hills.

Still working on it.

 

If multiple misfires, replace the pack and wires, not cheap, but the best step towards you finding your problem.

 

Does it do this first thing in the morning?
How many miles on the engine?

Engine Code: P0301

Land Rover Engine Code: P0301 = Cylinder 1 misfire detected Injector 1 excess emissions/catalyst damaging level of misfire.

Click to Process more Land Rover Engine Codes here

 

There is about 700 miles on the new engine; 83,000 miles on the truck.

Apparently the coil packs appear to be faulty. The wires are new, the plugs are new and NOW the coil packs are new and the misfires are gone.

 

Yea!
Coil packs must have gotten ruffed up when the heads got done.

 

SImple fix, and it's done, good job...