Variocam Issue?

[blue62]

Just for general information:
An important fact to remember when dealing with OBDII and it's related codes.

OBDII is not about engine performance!!!

It's primary function is Catalytic Converter performance.
It doesn't care about engine performance until that engine performance degrades to the point that it becomes harmful to the Catalytic Converter.

With that in mind:
Events such as misfires will set a code and the CEL on the first event.
Why??? Because misfires are immediately harmful to the Catalytic Converter.

An event that would cause a code for say a bad MAF sensor or a slow signal from an O2sensor needs two back events under specific conditions to set The CEL.

On the first event the corresponding code will be logged in the Pending codes memory.
If the event occurs on the next drive cycle, startup, as a back to back event.
The code is moved from pending to permanent and the CEL is lit.
If the event does not occur twice back to back then the codes is removed from the pending codes memory.


So Freserf:
If your reading this, if you unplug the Variocam solenoid and you do not get a code perhaps the DME/ECU does not see it as immediately harmful to the Cat.
So look in the pending codes on your scanner.

Hope this info helps in some way.

[Homeoboxter]

Originally Posted by blue62

Just for general information:

If your reading this, if you unplug the Variocam solenoid and you do not get a code perhaps the DME/ECU does not see it as immediately harmful to the Cat.
So look in the pending codes on your scanner.

Hope this info helps in some way.

It all makes sense, just one more thing to consider: changing valve timing not only affects performance but influences emission directly as well. So if it`s not working, that on its own should trigger CEL. When I did this test, CEL lit up when I hit the throttle.

[blue62]

Originally Posted by Homeoboxter

It all makes sense, just one more thing to consider: changing valve timing not only affects performance but influences emission directly as well. So if it`s not working, that on its own should trigger CEL. When I did this test, CEL lit up when I hit the throttle.

Yes if the valve timing change cannot be compensated for with fuel trims and ignition timing. It would most likely set the CEL on the first event.
Interesting piece of kit that OBDII

[freserf]

Originally Posted by blue62

Yes if the valve timing change cannot be compensated for with fuel trims and ignition timing. It would most likely set the CEL on the first event.
Interesting piece of kit that OBDII

Yes, very helpful or leads one in the wrong direction ... it is easier to diagnose if I had full engineering specs to go by ...

I left the variocam unconnected and drove around the block and it ran fine up to 25mph ... so I am left to pull the bank1 head cover and take a look at the variocam ... checking for anything odd such as really worn pads. Might be able to get to it this week ... just need to make a hold down tool for the cams. I'll update my progess ... thanks again for all of the input.

[blue62]

Originally Posted by freserf

Yes, very helpful or leads one in the wrong direction ... it is easier to diagnose if I had full engineering specs to go by ...

I left the variocam unconnected and drove around the block and it ran fine up to 25mph ... so I am left to pull the bank1 head cover and take a look at the variocam ... checking for anything odd such as really worn pads. Might be able to get to it this week ... just need to make a hold down tool for the cams. I'll update my progess ... thanks again for all of the input.

Hey good luck with it. Keep us posted

[freserf]

Originally Posted by Homeoboxter

It all makes sense, just one more thing to consider: changing valve timing not only affects performance but influences emission directly as well. So if it`s not working, that on its own should trigger CEL. When I did this test, CEL lit up when I hit the throttle.

Which code set?

[freserf]

Originally Posted by blue62

Just for general information:
An important fact to remember when dealing with OBDII and it's related codes.

OBDII is not about engine performance!!!

It's primary function is Catalytic Converter performance.
It doesn't care about engine performance until that engine performance degrades to the point that it becomes harmful to the Catalytic Converter.

With that in mind:
Events such as misfires will set a code and the CEL on the first event.
Why??? Because misfires are immediately harmful to the Catalytic Converter.

An event that would cause a code for say a bad MAF sensor or a slow signal from an O2sensor needs two back events under specific conditions to set The CEL.

On the first event the corresponding code will be logged in the Pending codes memory.
If the event occurs on the next drive cycle, startup, as a back to back event.
The code is moved from pending to permanent and the CEL is lit.
If the event does not occur twice back to back then the codes is removed from the pending codes memory.


So Freserf:
If your reading this, if you unplug the Variocam solenoid and you do not get a code perhaps the DME/ECU does not see it as immediately harmful to the Cat.
So look in the pending codes on your scanner.

Hope this info helps in some way.

Never thought of it that way ... protect cats ... one of the last cars I rebuilt required a new cat because it was melted and rattling around ... never gave a code though ...