Problem maybe due to K&N FIPK, need help

I installed the K&N FIPK intake and it worked fine for a month and a half in the city then when i hit the highway recently to florida from va, I noticed my temperature gauge was fluctuating rapidly b/t the half way mark where it should be, and zero (or low temp) it would shoot from the bottom to the mid section, stay there for a bit, fall back down, flicker up a bit but never go above the half way temp degree. It would also drop for distances of 20-30 miles.

I know the sensor is relocated during the process so am not sure if it was affected but why only during highway use? Anyone else have this problem?

Nissan dealership said could be a ground issue but it would cost 75 just to look at it and if it didnt occur at that point in time i would just be throwing my money away b/c they wouldnt be able to do anything.

Also, i was averaging 15 mpg on the highway at 70-75 mph, sometimes 13 and I only have the 2001 non supercharged engine. i dont think that the k&n helped. of course i have 31's... anyone else have 31's and k&n? and what are you experiences with that... alright, lots of questions, hoping for answers. thanks guys

Well, firts off, the sensor that got relocated wasn't the engine temp sensor. It was the intake air temp sensor. It tells the computer what the temp is of the air that is going to pass over the mass air flow meter. Helps to determine the air density.

Second, the grounding issue can cause gauge fluctuations, but it isn't usually confined to one gauge, as the ecu grounds are also affected. But, that might also explain the poor fuel economy as the computer's ground and the sensor's ground could be different.

I'd have them check it out, as it's a viable concern. Rather pay the checkout than guess from the internet on possible scenarios. Not a harsh, just a thought.

Just a thought before you go in. Make sure the connector on the engine temp sensor isn't loose.

The engine temp sensor is mounted near the upper coolant hose going into the engine. Just follow the upper hose from the radiator to the engine and wiggle any connectors you find along the way.

Being low on coolant might cause that gauge to bounce also.