2004 C5 Z06, stock LS6 engine.

Right in the middle of a WOT run my car shut off with no drama and will not refire. The only code is P0343.

Searches on the forum tend to point to the possibility of loose cam bolts, however I am wondering if it is simpler than that due to the fact that the car will not start. Most of those threads show that the car hard starts or runs poorly once started, and often the code starts as an intermittant.

I am trying to troubleshoot with a tech II and factory manuals, but the first step in the procedure is "start the car". I have fuel pressure and spark.

I have also read that the car should run (although hard start) with the cam sensor unplugged, and again, i can't start it. Before I take the engine out to torque my cam bolts, am I chasing the wrong fault?

Thanks.

 

Did you check for fuel and spark? If you view the live engine data, do you get a RPM value while cranking?

 

What's your Fp at the rail?

 

I'd take a look at the CMP sensor.

 

2004 Chevrolet Corvette V8-5.7L VIN S
Vehicle » A L L Diagnostic Trouble Codes ( DTC ) » Testing and Inspection » P Code Charts » P0343
P0343
DTC P0343

CIRCUIT DESCRIPTION
The camshaft position (CMP) sensor works in conjunction with a 1X reluctor wheel on the camshaft. The powertrain control module (PCM) provides a 12-volt reference to the CMP sensor as well as a low reference and a signal circuit.

As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads.

The CMP sensor 1X signal is used by the PCM to determine if the cylinder at top dead center (TDC) is on the firing stroke or the exhaust stroke. The PCM can determine TDC for all cylinders by using the CKP sensor signal alone. The engine will start without a CMP signal as long as the PCM receives the CKP sensor signal. A slightly longer cranking time may be a symptom of this condition. The system attempts synchronization and looks for an increase in engine speed indicating that the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes that the PCM incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. If the PCM detects that the CMP signal is constantly high, DTC P0343 sets.

CONDITIONS FOR RUNNING THE DTC
The engine is running.
The engine speed is less than 4,000 RPM .
CONDITIONS FOR SETTING THE DTC
The PCM detects that the CMP sensor signal is high for 1.5 seconds .

ACTION TAKEN WHEN THE DTC SETS
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

The above is a direct quote from the p0343 diagnostics. That code will not cause your engine to no start.

Check for spark and injector pulse. If good check your fuel pressure, if not, check rpm signal.

 

Thanks, all.

FP is solid at ~53psi. I was hoping it was the pump since the trans is currently out which makes that a cake R&R job.

Spark ok althogh I only checked one wire, and I see RPM on the tech II while cranking.

Next step was to pull the intake and swap check the harness and try a new sensor since I have on lying around. But if the car will run without a sensor plugged in at all I doubt that's the issue.

If i pull the valley cover can I see cam position fore/aft?

I am overseas this week so i haven't had a chance to dig deeper than that.

Seems like I should diagnose it as a no-start condition first then work out what's causing that code.

 

Did you ever figure this out? I'm having the exact same issue.

 

Yup. Timing chain snapped. I guess that's why they should be replaced every season.

Hopefully that isn't your issue, too!