Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
1994 Oldsmobile Eighty-Eight 3.8L Royale Hard Start/ Stalls at Idle
Well from my research, both of these codes correspond CAM and Crank sensor timings. Of course, one of the sensors being way off could cause the PCM to trigger both these DTCs.
You indicated that the crank sensor was replaced. Right? Why was it replaced? Same codes or just because? Do you know if the previous sensor was tested thoroughly?
The reason I ask is that perhaps it needs to be adjusted properly and/or the clearance of the sensor to the crank wheel could be off. This would affect the signal sent to the PCM.
What I would back probe both sensors and plot them against each other and then submit that picture to this forum. Someone might know the proper correlation.
There are many SD videos showing this, but at a high level, you'd back probe both sensors. Sent the scales appropriately so that you can see both wave forms together. You could just use your phone or whatever to capture the wave forms together. Make sure to get a complete cycle of the form. We need to see the beginning and ending of the two wave forms together, since they cyclic in nature.
In a more DIYer type style of response, using a incandescent, attached to block, are you able to get spark to occur to test light from a spark plug wire when the engine does not start? If not, this might indicate that the PCM is not seeing a valid CAM/Crank signals. Or, the ignition module is flaking out.
I, unfortunately, don't know your ignition configuration, e.g. does PCM cause spark or does a module cause spark.
If you're getting spark when car won't start, carefully spray carb cleaner via the brake booster hose, ensuring the check valve isn't preventing the carb cleaner from entering your intake. Does that start? If so, then this might indicate that you're having a fuel problem.
I'm sorry that I can't give exact instructions on how to preform these tests via this medium. But, don't worry. SD has plenty of example videos.
Now you know what tests you could run.
Best of luck; your persistence will pay off. It does for me!
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