98 Grand Prix 3800 sfi engine shuts off

[henri erhardt]

I read in a number of messages that a malfunctioning crankshaft position sensor is a strong suspect in intermittent shut downs of the engine. It usually start right up again. Does this engine also have a camshaft position sensor that has to be consifered?

Replaced CPS, still have same problem. This is my daughter's car and she is experiencing MORE symptoms: Most often, just before the engine shuts off, the radio volume decreases markedly, also the TRAC indicator light goes nuts. I experienced this once but had written it off as a coincidence. It seems to me that there could be a drop in control voltage or current which leads to an engine shutdown. Anybody have any thoughts or like experience?

[GTP Dad]

Welcome to AF! The crankshaft position sensor is your problem and needs replaced. It is located behind the harmonic balancer on the front of the engine. You will need either a large breaker bar or impact wrench to get the bolt out and then you will need a puller to remove the balancer. If you are not mechanically inclined you may want to have a mechanic change it out for you. As for the cam position sensor this engine does have one, it can be an issue but it doubt it in this case. If you are so inclined have it replaced at the same time as the crank sensor.

[henri erhardt]

Originally Posted by GTP Dad

Welcome to AF! The crankshaft position sensor is your problem and needs replaced. It is located behind the harmonic balancer on the front of the engine. You will need either a large breaker bar or impact wrench to get the bolt out and then you will need a puller to remove the balancer. If you are not mechanically inclined you may want to have a mechanic change it out for you. As for the cam position sensor this engine does have one, it can be an issue but it doubt it in this case. If you are so inclined have it replaced at the same time as the crank sensor.

I edited my original post with additional info. In short, replacing the CPS did not fix the problem. Could I get your feedback and any suggestions?

[R-ROD]

Originally Posted by henri erhardt

I edited my original post with additional info. In short, replacing the CPS did not fix the problem. Could I get your feedback and any suggestions?

Did you check the IAC valve? Sometimes they get stuck when they are heavily carboned up. Causes crazy idle and the engine dies when it's not working properly.

[henri erhardt]

Originally Posted by R-ROD

Did you check the IAC valve? Sometimes they get stuck when they are heavily carboned up. Causes crazy idle and the engine dies when it's not working properly.

The engine runs perfectly normal, no hint of anything going wrong there until it just cuts out. As I said, the single symptom observed is the radio volume going down just before the event.

[GTP Dad]

Check the battery cables both positive and negative. Also check all grounds on the car. This sounds like your voltage is dropping out and causing the car to die. I would also check the connections at the alternator and the power control center under the hood. All of these can cause the voltage drop out.

You may also want to check the cam position sensor. It can cause loss of reference and cause the car to stall.

[GTP Dad]

Check the battery cables both positive and negative. Also check all grounds on the car. This sounds like your voltage is dropping out and causing the car to die. I would also check the connections at the alternator and the power control center under the hood. All of these can cause the voltage drop out.

You may also want to check the cam position sensor. It can cause loss of reference and cause the car to stall.

[BNaylor]

I agree with Lynn (GTPDad). Also, you might considering checking the voltage reading on the battery statically and dynamically with a multimeter including charging system with engine running. Since the radio seems to be affected the 12v in IGN MAIN 1 could be low or loaded down. It feeds just about everything including radio power, engine electrical controls/PCM and the fuel pump. Troubleshooting the problem may require some patience and further testing to further isolate. In a worse case scenario you could have a defective ignition switch assembly. Good luck!

[richtazz]

I also agree with GTP and Bnaylor, sounds like a voltage problem (bad connection, internally shorted battery, dirty cable, etc...)