Chrysler Repair: GEO Metro Stops Running, camshaft sensor, cam shaft

Question
My daughter has a Metro that she says seems to just stop in trnasit from time to time.  She says it's just like it quits running.  She can usually start it up after it has sat for awhile.  She lives in Phoenix, and says that this started when the temps got extreme this summer.  I know this isn't allot of info, but do you have any ideas what we should be looking at?  A mechanic has just replaced plugs, wires and fuel filter.  Still has trouble.

Answer
P.S. Another approach that would help confirm whether this is the reason for her problem is to go to a shop and have the engine computer challenged to readout any fault codes it may have noticed. There is probably a code for the failure of the hall effect sensor, which if present would confirm my hypothesis or if not might tell her what is wrong. You might ask her if the mechanic did that readout already or not. It might cost $40 for the readout, but it might save the unnecessary cost of a unneeded part. Some times the car's have a self readout technique using the ignition key (like turning it on-off-on-off-on then counting the flashes of the check engine light, but I don't have the procedure or code list even if that were possible with her car. But that might be worth asking about at a GM parts counter to see if anyone there would give her a tip on how to do it herself. Or try the allexpert list for GM or Chevy or Geo cars to see if the experts there could tell you.


Hi Sue,
The Metro is a GM import car so I am not really expert in that model. I do have an idea though which she might want to try. There is in most contemporary fuel injected cars a solid state electronic detector that senses the rotational position of the engine's pistons in order to properly time the spark. It is called a "hall effect sensor" and it usually is inside the distributor. (Newer models may position this near the flywheel or the cam shaft, in which case it would be called a crankshaft or a camshaft sensor). In any case, a knowledgeable auto parts store would be able to find which type she has and which exact part number fits her car's engine.
These hall effect sensors have the characteristic that when they are in the process of breaking down they do as the component warms up from engine heat nearby. So their signal stops, then the engine dies and cools down, the sensor recovers and the engine will start again. They cost about $50 and an intelligent handy person can easily replace it by merely opening the distributor cap, lifting off the rotor, and removing the old unit by unplugging its connector wire and putting the new one in its place. No other adjustments or tools needed.
So that is my best uneducated suggestion.
Roland