Idle & Off Throttle Hang - Sometimes

[Monarols71]

Thanks. Finding one, and then not having to pay a kings ransom for it will be hard. And then it might not fix it. Oh well.

[Monarols71]

More stupid questions. Sorry.
Even though the VS 3 1/2 and VT 1 V8s use the same PCM no. 16234531, could we use a VT one with the VATS turned off in our VS
Apart from the memcal, is there any difference between an Auto and a Manual PCM, or are they identical.
Will the DTC49 clear if the EFI relay is pulled (tried it but didn't work), or do those thieving pricks have to do it for another $113.30.

Regards

[The1]

that should be it.

To clear the code pull the battery for 10 seconds or leave the pcm disconnected for 5 minutes. Or if you have a logging adaptor you can send a Clear DTC command through flashtool.

[Helical]

More stupid questions. Sorry.
Even though the VS 3 1/2 and VT 1 V8s use the same PCM no. 16234531, could we use a VT one with the VATS turned off in our VS
Apart from the memcal, is there any difference between an Auto and a Manual PCM, or are they identical.
...

Yes, I am running a VT S1 PCM in my VS with VS S3 loom and DRRR bin

Troy

[Monarols71]

Thank you.
We don't have an NVRAM, so flashtool is possibly not suitable for us. I'll have the PCM disconnected to do more checks on the weekend, so that will reset it. I'll redo the tests at the distributor connector, and not at the PCM connector, so that will discount a dodgy connection.

[Monarols71]

More testing done and more thinking. It can't possibly be the PCM, as it was sitting on the bench in bits with a V6 unit for comparisons, when the D3 connector voltage was tested.
D3 is the INPUT for the cam signal, so it has to be the hall sensor not giving the correct voltage to D3. But I'm not game to run the tests as per the manual, because it seems to contradict itself.
Have just had the laptop connected to the car and watching "Item Lists > Engine Data Only". Cold start and idle only, the "cam signal" data flashes from present to missing on a regular basis. It goes something like "present - missing - present - missing - missing - missing - present - missing - present - missing - missing - present etc. I hope that makes sense.
We did that a couple of times with the same result. Then after 10 minutes or so and with some decent coolant temperature, the cam signal is constantly "present". After 6 minutes idling, it didn't flash "missing" once. It seems to be temperature related, so I'm guessing our 6 month old distributor hall sensor plate is up the sh*t. Got me fcuked.
Regards

[VL400]

In terms of what the software is doing for a code 49, all it checks is when the cam pulse arrives at the PCM has there been 8 ref pulses. If there has been 8 or more then all is ok, less than 8 it starts incrementing a counter. When the counter exceeds a threshold it sets the code.

So, either you are getting extra cam pulses or missing some reference pulses. Dont have an oscilloscope (or could borrow) by any chance?

[Monarols71]

Thanks VL400.
Unfortunately I don't know anyone with a scope these days.
But after rereading the manual regarding DTC49, it says "If the sequence of pulses is not correct for 15 occurrences, a DTC49 will be set, indicating an intermittent problem with the cam signal or crankshaft sensor reference signal." The car "died" previously with a sensor fault, but we had no spark in that instance (cam sensor), and the sensor plate fixed it. We changed the ignition module while we were at it, also.
I'm still leaning towards the sensor plate in the distributor, but, is there another "external" cam sensor that would (could) work if I made something to mount an external cam sensor (out of the distributor) off the harmonic balancer?? Whether it be hall effect, proximity, magnetic or whatever
Thanks

[VL400]

The cam sensor needs one pulse per engine cycle, so the place it has to be is off the cam - the dizzy-less V6 uses the timing gear with a magnet embedded in it and sensor mounted in the timing cover.

[Monarols71]

Your right. For some stupid reason, I keep thinking crank sensor (resulting in the last posts stupid idea), and keep writing cam sensor.
And it definitely is the cam signal (according to TunerPro) that went missing , appearing etc. The car doesn't misfire or anything.
Now that I've cleared myself up, I'll plug the laptop back in and see what happens.