Sporadic misfire, and various error codes

[jemi]

I had the following error codes registered and a very erratic tickover when idle,

I had both Variocam actuators replaced, 3 months ago, and I have again got the same error codes as I had before the actuators were fitted:

P0300 - misfire detection
P0306 - misfire cylinder 6
P1371 - valve lift control checksum error
P1360 - valve lift control cylinder 6

The misfire is very sporadic, it does not have any regularity to it, it can happen when the car is first started, or when the car is warm, and when the misfire occurs the car can be driven and at the end of the journey (sometimes) the misfire is no longer evident.

to add to the confusion the car can also be driven for days with no misfiring, the problem (whatever it is) is very intermitant.

These error codes are the same as before I had the new Variocam actuators fitted...any ideas anyone?
Getting frustrated now...!!

 

My car is a 2004 Porsche 996 C4S with 129000 km on the odometer

Edited April 29, 2015 by jemi

[farmer boy]

I had a similar problem - (misfire cyl 6) which casued a rough idle.  The garage decided it was a variocam actuator problem but I decided to change the plugs and coil packs  first and that  solved the problem. 

[Ahsai]

When you said variocam actuators, you mean the actuators for valve lift (as opposed to timing) and you replaced one on each bank?

 

Since the DME uses O2 reading to detect valve lift misbehavior, I would also suspect the misfiring is throwing it off. I like the idea of changing all the coils and spark plugs first and see if that changes anything especially if the coils are original.

[Odd Arne Klinge]

Ahsai and jemi, I would also suggest that. I have changed a couple of sets of these, never seen the valve lifter errors though.