I have a vortec 350 setting a trouble code P1345, the truck has excessive cranking to start but idles fine, while driving down the road when reaching 30 mph, the truck loses power and will not pick up speed, pull over to the side of the road and shut it off and restart the truck and it will run fine again until it acts up, then it losses power and will have a hard time reaching 30 mph.

Be sure to check the Idle Air Control Valve...can be just dirty, or may need replaced...also thoroughly clean out the throttle body, spray and wipe clean...also clean the Mass Air Flow sensor, it requires a specific spray that does not erode the unit...hope this helps.

Throttle plate may need cleaned and check your plugs.

Could be the cankshaft sensor.

Trouble Code: P1336

CKP Sensor System Variation Not Learned
Possible Causes:


Set the parking brake and block the drive wheels for safety. Verify the hood is closed. Read the trouble codes. If a code is set, refer to that code. Start the engine. Allow engine temperature to reach at least 158?F (70?C). Then key off. Select Crankshaft Position Variation Learn procedure on Scan Tool & start the vehicle. Apply the brake pedal firmly and verify the selector is in Park. Increase accelerator pedal position until fuel cutoff is reached at the test rpm (e.g., 5150). Quickly release the accelerator pedal after fuel cutoff is reached. The CKP system variation compensating values are learned when the engine speed (rpm) decreases back to idle speed and the procedure terminates. Read the trouble codes and recheck for DTC P1336. If DTC P1336 runs and passes, the CKP system variation "learn" procedure is complete. If not, look for other codes. If no codes are set, repeat the test procedure.

Sounds like fuel problem to me?? Have you changed the fuel filter ?

1345 is cam and crank sensor correlation its mainly the cam sensor going out, also the delay start that also trigger a camsensor code they call it excessive crank time check the fuel pressure that is capable of setting a cam code (1345) If fuel pressure is good (55-60 psi) expect to replace the camsensor you might as well do the crank sensor heres a nightmare on this code it can set if the distributor is off one tooth and yes these distributor have high failure rate

vehicle shuts down while driving down road and does not start backup for at least 20 minutes, could be a bad crank sensor. if bad it will start and run fine, but it will keep shutting down until fixed.

Let's back up. On top of the distributor with the cap removed there is an "8" and a "6" on the edge. With the harmonic balancer set with its' mark lined up with the timing pointer of the timing chain cover, the tip of the rotor should be lined up with the "6". If not, remove the hold down bolt, raise the distributor until the rotor can be turned, rotate rotor and set down until rotor of tip lines up with "6". See if it cranks normally then. A worn distributor gear (sharp edges) will also set this code and cause starting problems.

Had the same problem with my '96 Silverado with 350 Vortec. The truck would only crank. It would start if fuel was poured down the throttle body. Could not hear the fuel pump hum. Fuse was good, but could not hear relay click. Relay was good, Did some electrical wiring trouble shooting. Turned out that one of the connectors that clasp onto one of the pins of the fuel pump relay wasn't making a good connection, too loose. I just stuck a peice of wire into the connector and pushed the relay back in. Relay clicked, Truck Started. It's been more than 4 yrs. since I made that McGuyver fix. Still firing.