I have installed hooker LT's, had the computer tuned by PCMforless and also replaced the opti and water pump and now the car will not run right. It will idle but it is a rough idle and will not acclerate past 1800 rpm's. The fuel pressure and spark are fine, the only code it keeps flashing is a crank position sensor malfunction. I replaced the sensor and checked the wires and they seem fine but it is still doing it. Do you think it is in the computer/tune? I did not install a LT4 knock module I just requested that the knock sensor be deleted in the tune.
Zack

 

I just had mine tuned and I got the same code. I haven't replaced it yet, but I sure hope it's not the tune.

 

Why did you delete the knock sensor? Now If your engine is getting knock the PCM will not be able to retard the timing. That doesn't sound like a good idea to me but maybe I'm missing something here.

 

The crank position sensor is not used for any engine functions on an LT1. It is only used for the OBD2 computer requirements to detect misfires. So the crank position sensor should not effect performance. Might double check the spark plug wires are going to the correct place on the opti... its easy to get them crossed up. Opti might not be working right also.