Hello all, my 96 Z/28 decided to throw the code P0336 at me. The guy I got the car from told me the codes being thrown were for the emissions controls, which he wasn’t wrong as those are there too, but this concerns me a little more. Any ideas whats up with its crankshaft position sensor?

 

Code can be due to the signal from the crank sensor not matching the cam position signal from the Opti. However, the crank position sensor was added to the LT1 in 1996 with OBD-2 requirements, and is only there for misfire detection, and does not affect how the engine runs. It's a hard code to track down because you need a scanner with GM “enhanced parameters” to read the angular difference between the crank and cam position.

Check the harness connector, make sure the CKP wires are not too close to a high voltage wire that can induce false pulses on the CKP wires.

How does the engine run? I have tracked down a couple cases of this where the Opti was not correctly indexed to the cam dowel pin. Stock cam, or aftermarket, possibly advanced?

 

Well, before it shot out it’s coolant level sensor, it cranked with no issues when cold. Now I’ve got to give it a little gas to get it to crank. Though it was throwing code p0336 before the coolant sensor decided to go. But once it’s going the engine runs pretty smooth. It’ll still rev just fine and the oil pressure stays between 60 and 22 when revving and letting off. I don’t know if it’s an aftermarket cam or if anyone has opened up the engine, however the gaskets for the valve covers and intake are new, so someone very well could have opened it up.

 

P0336 doesn't cause any operational problems. It does keep the system from being able to detect misfires and set codes P0300 thru P0308 for those misfires.

Beside the signals from the Opti actually being "off", the code could be set by a loose reluctor ring on the end of the crankshaft, excessive timing chain wear, sensor contacting the reluctor wheel, damage to timing cover, or excessive backlash in the distributor drive.

If you have access to a GM Tech-2 scan tool, or want to pay a dealer to scan the PCM, you need to get the value for "CKP:Lo Res Angle"