Rough idle, low power, code p0340

[Paul13pp]

Hi, my VY has sat for several years & now it has been running for a few days with fresh rego..
There is a code logged p0340 cam angle sensor signal missing.
The idle is really bad & it stalls at the lights & sometimes shifting to drive.
The power from the engine is also really low although once above idle it appears to run on all 6.
The week before, the idle problem was there but the engine performed 3 times better.
I've replaced the cam angle sensor with no difference.
The wiring looks good & I can measure 12 volts on one side of the cas & 6 volts on the other.
I'm thinking DFI module might be faulty but broke a 13mm socket trying to undo the two bolts holing it in.
Can't seem to find any info on this code related to the ecotec.
I can clear it, start the engine & it immediately returns.
Any ideas please?

 

[Jolls]

Hi Paul

I couldn't find anything in the VT-VZ manual under VY relating to P0340. I did find P0341 DTC P0342 V6 PCM - CAMSHAFT POSITION (CMP) SENSOR SIGNAL INTERMITTENT and P0342 V6 PCM - CAMSHAFT POSITION (CMP) SENSOR SIGNAL MISSING

The detail for P0342 is below:

CIRCUIT DESCRIPTION
During cranking, the ignition module monitors the dual crank sensor 3X signal. The 3X signal is used to determine the correct cylinder pair to spark first. After the 3X signal has been processed by the ignition module, it sends a crankshaft reference pulse to the PCM. When the PCM receives this pulse it will command all six injectors to open for one priming shot of fuel in all cylinders. After the priming, the injectors are left "OFF" for the next six crankshaft reference pulses from the ignition module (two crankshaft revolutions). This allows each cylinder a chance to use
the fuel from the priming shot. During this waiting period, a cam signal will have been received by the PCM. Now the PCM begins to operate the injectors by energising each injector based on true camshaft position. With the engine running, the PCM monitors the cam and crankshaft reference pulses it receives and expects to see six camshaft reference pulses for each cam pulse.
CONDITIONS FOR RUNNING THE DTC
• The engine is cranking or running.
CONDITIONS FOR SETTING THE DTC
• The PCM detects the Camshaft Position sensor signal is low when the signal should be high for five (5) seconds.
ACTION TAKEN WHEN THE DTC SETS
• The PCM stores the DTC information into memory when the diagnostic runs and fails.
• The Check Powertrain MIL will not be activated.
• The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the History Data.
• Once DTC P0342 is set, the PCM will determine the fuel injection sequence based on the last fuel injection pulse received. In the calculated SFI mode, the engine continues to start and run. However, with the fault present, only a one in six chance of the correct injection sequence exists.

DIAGNOSIS
A fault may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.
Check for:
• Poor Connection or Damaged Harness - Inspect PCM harness connectors for backed out terminal X1-B6, improper mating, broken locks, improperly formed or damaged terminal, poor terminal to wire connection and damaged harness.
• Intermittent Test - If connections and harness check OK, monitor a digital voltmeter connected from PCM terminal X1-B6 to ground while moving related connectors and wiring harness. If the failure is induced, the voltage
reading will change. This may help to isolate the location of the malfunction.

The diagnostic chart is too long and detailed to post here. If you search this site, or google Just Commodores VT-VZ manual link you should find a way to download a copy of the manual. You can navigate the manual easily using adobe or foxit. The DTCs you are looking for are in SECTION 6C1-2A - DIAGNOSTIC TABLES – V6 ENGINE

You will be able to follow the diagnostic chart to work through to a resolution step by step. I'd follow the diagnosis step by step so it is done in a methodical and logical manner, but I'd be focussed on the connections/harness between the CAS and the PCM as that is where the signal is not being received.

Cheers n Beers
Jolls

 

[Paul13pp]

Hi Jolls & thanks for your reply.
It appears I may have found the culprit.
A missing magnet on the camshaft gear as per photo.
This might be interested to fix without pulling the whole thing apart...