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Discussion Starter #1
We got this 4 door cobalt Lt with a bad crank. Number one spun a bearing. We pulled motor, installed new Hastings rings, King bearings, and new Gm crank 58 tooth wheel. right out of the crate,
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new melling valves, new Cloyes timing chain setup, felpro gaskets. over 150 psi compression. 60plus psi fuel pressure. New standard cam and crank sensor.

It will try to start with crank sensor plugged in and tach will move, rpm changes on code reader while cranking. Unplug crank sensor it will start and run motor is quiet runs ok but not like it should. If the crank sensor is plugged in while running it will continue to run but the tach never moves and it throws the crank position relearn code.

We have replaced the ecm and the trans module behind it. all the grounds under the hood have been cleaned. the fuse box has been pulled and checked, all the fuses and relays in that box have been checked and swapped. All the fuses and plugs have been checked in the bcm. The wires under the hood are taken out of the loom and checked for breaks. The wires have been replaced from the crank sensor to the ecm including the 3 pins in the plug. There is no more extension plug . The sensor has 5 volts to it. and the sensor has been swapped out with two new ones and multiple junkyard ones. The cam sensor has been swapped with junkyard ones and new ones. seats are out and the ground under the driver's seat is clean. The cluster has been pulled and unhooked and put back. Everything the bcm controls works. I have read on this forum and every forum i can find and have done everything anyone ever had trouble with on one of these things. We have a tech 2 laptop hooked up also. Everything on the car works fine besides not reading the crank sensor along with the tach not working. I don't know what else to check. You can see the crank sensor right by the tone wheel in the pic when the crank was laid in there.Thanx for any help.
 

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Discussion Starter #3
We just swapped the entire engine harness and BCM. We checked the cam reluctor to make sure it hasn't spun.
 
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