Pontiac Grand Prix Stalls, Oldsmobile Crank Sensor

Question: Yes, I have a 1998 Pontiac Grand Prix 3.8L. The engine Rpms jump all over the place then the car often stalls at random times. Somtimes the car will stall sitting at a stop in idle or even when just driving down the road it will shut off.
 Mechanic: Is the engine RPM problem at idle, accelerating, or while driving at asteady speed?

Idle, then on acceleration it will jump way up then drop super fast. At a steady driving speed of 25 mph the RPM's will jump up and down followed by an engine stall most of the time.
 This problem on your Pontiac sounds like a possible crank sensor is going bad. This is common on the 3800 V6 engine. Sometimes tapping on it with a long extension can get it to act up. Or after the engine dies, pooring cool water on it will cause it to start again.

Is a crank sensor an easy fix? Or what price am I looking at to get it repaired by a mechanic?
 The sensor is located behind the lower crankshaft pulley. Not really something a non-mechanic can do in your garage. The large center bolt ould need to be removed and the pulley taken off. Then installing the crank position sensor with a special tool that alignes it ith the ribs i the back of the pulley. The sensor is about $75, and labor cost at a shop would be about 2 hours.

Okay. I've also been told it could be the mass airflow sensor too. Could this be an easier thing to fix before shop prices?
 Yes, that is also possible. Usually that will set an engine light and codes. You can try and unplug the sensor, then start the car and drive it to see if that helps. This will cause the engine light to come but it will go into a backup parameter in the computer- if it runs better, then the MAF is the problem. It would be an expensive guess to replace just to try and you cannot return an electrcial part to the parts store.

 

Question: I have a 2003 Oldsmobile Silhouette and im trying to replace the crankshaft positioning sensor but I cant find it. I'm sure its hiding in plain view I just cant seem to spot it. Any help would be appreciated.
 Mechanic: Do you have the 3400 or 3800 engine?

It is the 3400 V6 engine.
 That engine actually has 2 crankshaft position sensors. One is behind the crank pulley and the other is in the side of the block between the engine and firewall. That one is hard to see and get to.

Ok. The one that Autozone supplied me with is about 3in high with one spot for a bolt I'm thinking 8mm and the plug in area is sideways with 2 posts for connection. not sure if that can help determine which one it is.
 Yes, that is the one on the side of the block. It is either in the front, near the oil filter, or on the rear, sort of between the engine and transmission.

ok thank you for your time. I pulled the power steering pump off thinking I had the right sensor only to find that it wasn't haha. That was just a waste of Time. At least it was not hard to remove and did not take a lot of time. This should help me a lot. Thanks again for all your help.

 The sensor that is behind and below the power steering pump on the 3400 engine is the cam sensor.