I just put a motor in my 96 Z28 I bought the car with a blown motor and found one with 63000 miles to put in for now. The car runs good when cold and above 2500rpm. When it warms up idles like it has a cam in it and it isn't all there at low end. It is throwing a code for crankshaft sensor but i put a new one in and still throws the code. any ideas

 

When ever you have a sensor failure, you always check the connector for rudimentory items. In the case of the CKP, check for 12 volts from the pink to the pink/black wire. This voltage should be almost exactly the same value as measured across the battery with KOEO. No voltage at the connector or a difference at the connector compared to the battery is also a problem.

If we assume you have a DTC 335, this code usually has to deal with the yellow wire from the sensor to the PCM red connector first pin. Ohm it out with it disconnected and engine off.

The sensor or the signal will not effect the way the engine runs. However, it's 12 volt source is the same one used for the ignition. Therefore if the 12 volts you measured was low at the CKP, it should also be checked at the coil on the pink wire and at the pink wire to the ICM also. If the 12 volts going to the ignition components is low, it may account for your running issues.

Just FYI. There are many sensors on every car that are connected to the same 12 volt supply line. If one sensor has an internal short and pulls the 12 volt line low, it will effect all the sensors on the same 12 volt supply line. I've seen a sensor pull a 12 volts supply low to the point the sensors on the line stop working but it still didn't blow the fuse.

In your case, one of the ignition components could be sinking the 12 volt line low and causing weird problems with anything on the same supply line. Not likely but possible.

 

Ok thanks for that bit of information anything will help i will check this when i get over to the car it is in storage right now. Thanks again