I've been going through the steps, trying to diagnose what initially felt like a miss when the engine was idling, after going through the motions about the only thing that seems to stick out is the Left Exhaust VVT is way out.
When the car is at idle, I get an intermittent drop in RPM, nearly stalls sometimes, then the RPM's come back up only to drop again a few seconds later. It's very regular. Normal driving doesn't seem to be an issue, only idle.
I have:
*Checked for air leaks - Inspected hoses and used throttle body cleaner around all air hoses listening for rpm changes, nothing.
*Cleaned the throttle body, now shiny.
*Removed and inspected the coil pack and spark plug closest to the turbo, thinking maybe the plastic had gone hard and was starting to crack. Both look pretty new. Coil pack is still pliable rubber, no cracks.
*Bought a Tactrix (Yay) and started logging AVCS parameters. And noticed this, all the way through to log too, not just in one spot:
- VVT.png (44.2 KiB) Viewed 4897 times
I'm guessing, this isn't normal or ideal? OCV needs to be removed and cleaned or replaced?
Each time the airflow on the MAP sensor changes at idle, the final fuel enrichment is readjusted and trims or adds fuel. Its the equivalent of trying to play darts after a keg of beer... your unlikely to hit the bullseye if the ground, your arm and your legs are all moving.
