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1996 Chevrolet K1500 Tahoe 5.7L Engine: P1345 and P0300 Codes - Dead Cylinder 1, Intermittent Misfire on Cylinder 8

Model: 96 Chevy K1500 Tahoe Fault Code: P0300 Posted: 2008-07-08 15:44

I own a 1996 Chevrolet K1500 Tahoe with a 5.7L V8 engine. The truck was purchased without an original motor, and I installed a long-block engine. It starts reliably but exhibits a dead cylinder on number one and intermittent misfiring on cylinder eight when put into gear. My Tech II scan tool shows two trouble codes: P1345 (Crankshaft Position Sensor - Camshaft Position Sensor Correlation) and P0300 (Random/Multiple Cylinder Misfire). I'm wondering if the P0300 is directly caused by the P1345. Should I attempt to adjust the distributor by one or two teeth? I've already tried moving it back one tooth, which worsened the issue—now I’m considering shifting it two teeth forward. The truck was previously disassembled by someone untrusted, so I suspect potential issues with the crankshaft position sensor or its wiring. The distributor is new and not suspected as a root cause. However, given that the P1345 code indicates a correlation issue between the crank and cam sensors, I’m concerned about improper sensor alignment or installation. I’ve also noticed an unusual intake manifold design: instead of standard plastic poppet valves with clips and prongs, some have two wires connected at the nozzle end. This appears to be an early Vortec injection system—was this a 1996 model feature? Or could it be a conversion setup? I’d like to avoid replacing parts blindly. Any insights on how to diagnose or fix this issue would be greatly appreciated.

Related fault codes
P0300P1345
Comments (7)
Anonymous 2008-07-08 17:07

If you have access to a Tech II scanner, check the camshaft position data and ensure the camshaft retard angle is very close to zero. Try adjusting the distributor in the opposite direction and observe how the readings change.

Anonymous 2008-07-09 10:46

I adjusted the distributor last evening by chance—on the first attempt, moving it slightly, the camshaft retard angle went directly to zero without any gear adjustments. The P1345 code disappeared. However, the P0300 code remains, and cylinder one still shows a consistent misfire. I couldn’t perform an injector balance test via Tech II, so I didn’t have access to a fuel pressure gauge or command testing for individual injectors. The spark plug on cylinder one looks brand new (white). I don’t want to replace parts without understanding the root cause. Additionally, during my intake cleaning after years of storage, I noticed that some of the 'spider' poppet valves were different—instead of standard plastic tubes with clips and prongs, they had two wires connected at both ends near the nozzle. Was this an early Vortec injection system from 1996? Or a conversion modification?

Anonymous 2008-07-09 17:08

That configuration appears to be part of an updated injection system—though it may not necessarily be functioning correctly. Are you confirming spark presence and compression levels? If the engine is new, incorrect valve adjustments could still be a contributing factor.

Anonymous 2008-07-09 21:19

Confirmed—it was an upgraded injection system. Over at O'Reilly's, there’s a conversion kit to switch from sequential to multi-point fuel injection. I installed it and the misfire disappeared. The issue stemmed from a mistake during installation: on the newer injectors, each has a plastic nozzle about 1.5 inches long that slides into the intake manifold—similar in design to OEM poppet valves. The installers had removed these plastic inserts entirely, leaving the injectors barely seated in their holes. I suspect cylinder one’s injector was not properly firing or even partially dislodged. It likely wasn’t making contact with the intake. This is a great example of how improper installation can lead to serious performance issues—especially on older trucks. I’m glad this post might help others. Also, note that P1345 will trigger if the distributor isn't within 2 degrees of proper alignment. While P0300 may have multiple causes, this case highlights the importance of correct installation and diagnostics. Thanks for the helpful tips!

Anonymous 2008-07-10 04:59

The updated injection system is excellent—but only if installed properly.

Anonymous 2008-09-08 12:20

I replaced both the crankshaft position sensor and timing chain, but I still experience intermittent misfires during acceleration. The P1345 code persists, though no P0300 code appears. Any suggestions for further troubleshooting?

Anonymous 2008-09-08 12:48

Double-check that the distributor is properly installed—misalignment can trigger P1345 and cause misfires.