Pontiac Repair: High Oil Pressure Reading, oil pressure gauge, low oil pressure

Question
Hi..
I have a 1995 Pontiac Grand Am, 3.1 L engine.
My problem is the oil pressure gauge reads in the normal range ,40-50 psi at idle,when i accelerate it pegs out at 80 and stays there until i let off the gas and return to idle.
I know this cannot be right.
The engine was replaced in November due to a failure from low oil pressure.It runs fine,no noises but when the pressure pegs,the SES light comes on.
The oil pressure sensor is new,put in with engine due to the fact the replacement (used) engine had a sensor for a light setup and i have a gauge .
I'm worried ,since i blew one engine already...is this a faulty oil pump/relief valve?
Thanks in advance for your help

Answer
Hey Jim:

I'm going to say the oil pressure sensor is bad. what you discribed is a classic symptom of a bad sensor. The spring inside the sensor goes bad and it makes the guage all wacked out like you mentioned.. Even 40 PSi is high for hot at idle. If you that nervous about it then have a shop put a mechanical gauge on it and see what that reads if the pressure is normal then the sensor is bad. it's very off for a gauge to go bad. If the sensor that was put on was a cheap aftermarket then all the more reason it went bad. Use a genuine AC delco part only. High oil pressure is not a bad thing. Low is! Good luck.