1990 Olds 98 ignition shuts off. Restarts 1 to 12 hours later

Maintenance/Repairs
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1

Module or cam/crank sensors most likely? How difficult are the sensors to replace if module doesn’t fix problem? 120 k mileage.

2

Start with a used coil and module and hope they are good because new ignition parts cost more then the car is worth (generally.)

Module is just a simple bolt-on, make sure you clean everything because it grounds through the mounting.

Crank sensor is difficult because special tools are needed to get the crank pulley off.

3

thanks

4

I’d agree with rattlegas. I’d look at the coil first. Heats up and goes south, then cools down and is ok again. Crank and cam sensors aren’t likely to be self-healing when the cool off.

5

I too am going to go with rattlegas on this.

You clearly have something that’s become heat sensitive. A good place to start to look is with things that contain windings. Coil windings are insulated from one another with a varnish like coating (typically polyimide/amide) that becomes brittle with age, and does not have the same thermal expansion coefficient as the copper wire. Once embrittled, when the wire expands from heat cracks open up in the coil windings and they short out. At that point they no longer functionally form a coil. Just a short.

6

Check cam/crank sensor wiring for deterioration from oil leakage.

7

Thanks guys. All good answers. I neglected to say that hot or cold, wet or dry, it shuts off with no correlation to how long it’s been running. Sometimes 2 minutes, sometimes a few days. It has a multi-coil ignition, so I think it’s more likely to be the ignition module. It usually starts running rough then shuts down completely .When it starts there’s no miss.

8

I have a 95 Olds 98 Regency which does the same thing in regards to randomly shutting off. It will, however, restart just after pulling over and stopping. It is totally random and not often - maybe once a month or less. Have you found any solution?

9

Whenever you are having ignition system problems it is wise to check the DC power to it while the trouble is occurring. That should always be the first step in the trouble shooting process, especially with these symptoms that are described.

10

My son-in-law had this problem on his 1998 Grand Prix. I told him to have the crankshaft position sensor replaced and if that didn’t fix it, I’d reimburse him the cost. I didn’t have to pay.

11

The CPS sensor is a common problem area alright. There should have been an error code stored in the ECU for that problem.

12

No check engine light. Didn’t check for stored codes.

13

@Cougar‌

I’ve fixed many a car with a bad crank sensor . . . CKP by the way . . . that never had any stored fault code pointing to it

But it is somewhat uncommon to have no code

14

Most of the defective crank sensors I’ve replaced never caused the Check Engine light to come on.

Tester

15

Thanks for the info on CPS sensors fellas. You would think a bad sensor would should present an error code. Perhaps the fault is the output signal is degraded somehow or distorted enough that the engine won’t run but the ECU thinks it is still okay so no error code is generated.

16

CPS = Child Protective Services

17

Don’t those have 3 coils which sit on the ignition module? If so take the coils off of the module and clean any corrosion that is built up. I had a similar problem with a 3.8l gm and the surface between the coil and the ignition modules had a bunch of corrosion and I think the coils ground thru the module.

Anyway I wire brushed all of it and it fixed the problem.