Variocam thoughts and questions

[Homeoboxter]

Originally Posted by sfkjeld

As described below, I’ve had a 1341 CEL issue for over a year. Exhaust cam timing. The interesting part is that the car always runs great. And if the CEL is fully cleared with the Porsche Durametric scanner, it will pass CA smog (I’ve done it twice).

I put in a low temp thermostat a few months ago. The car def runs cooler unless in traffic on a hot day. Then it runs as it had with the stock 185 thermostat.

But it appears running cooler seems to effect the 1341 CEL. I have a cheap scanner and periodically clear the CEL when I annoys me. With the lower temps tho, the CEL isn’t thrown so quickly. I can go weeks now and it was days before. But now, if I leave the CEL on, the computer clears it once in a while. I assume it’s because the vario cam works better with a cooler motor? Anyway, weird.

Just hypothetically, if the O-rings inside the variocam are worn out/broken and they no longer can hold the pressure as they are supposed to, they can leak more when the oil is hotter and thus thinner, leading to more frequent triggering of the CEL. So it does not work better in a cooler motor, just it`s more likely to fail when it`s at normal operating temperature. Assuming this to be correct, thicker oil would give you even less frequent CEL.

[sfkjeld]

Originally Posted by Homeoboxter

Just hypothetically, if the O-rings inside the variocam are worn out/broken and they no longer can hold the pressure as they are supposed to, they can leak more when the oil is hotter and thus thinner, leading to more frequent triggering of the CEL. So it does not work better in a cooler motor, just it`s more likely to fail when it`s at normal operating temperature. Assuming this to be correct, thicker oil would give you even less frequent CEL.

Yes, that was my theory as well. I went to a 40wt oil but didn’t really notice much difference.

Any idea why the CEL would be clearing on its own? Is it documented anywhere what the 1341 CEL algorithm might be? What sets it off? How many degrees off, at normal engine temp, and maybe the number of times it has to happen? Over a period of time maybe?

[blue62]

Originally Posted by sfkjeld

Yes, that was my theory as well. I went to a 40wt oil but didn’t really notice much difference.

Any idea why the CEL would be clearing on its own? Is it documented anywhere what the 1341 CEL algorithm might be? What sets it off? How many degrees off, at normal engine temp, and maybe the number of times it has to happen? Over a period of time maybe?

The CEL will clear itself after a set number of drive cycles without the issue reoccurring.
Each issue or code has it's own number of non occurrences before resetting the CEL.

Sorry I don't know the algorithm for the 1341 to set.

Most issues that are not immediately harmful to the Catylitic converter's have to happen twice or back to back over two drive cycles.
On the first occurrence the code is set in the pending area of memory.
If the issue happens again on the next drive cycle that code is moved to the permanent area of memory and the CEL is set.

Issues that are immediately harmful to the cats like misfires set the CEL on the first occurrence.
That's my limited understanding of how it works.