Today I completed the sparkplug change, and ran a quick scan to see if the plugs were in correctly, and all of the boost system was put back together. I had revented the charge cooler yesterday.

Overall lots of good things here. The ATS-V started, and is making boost. No misfires during the WOT run (!), minimal KR, no torque management advance.

I am running a bit rich on bank 1 which I suspect is a result of previous misfires by plug 3. I am hoping that after the LTFTs relearn that will settle out.

What I learned on the spark plug change: plan for it to take as long as it takes. It is a marathon of moving the charge pipes and multiple vacuum hookups out of the way in order to reach the coil packs and plugs.

The coil pack connectors are a special pain — they have a locking clip that needs to be pulled back, then the tab-like section just behind the clip gets pushed down, then you can pull the connector off. However, the connector has a seal which makes pulling it off difficult. Try to practice on one that is easier to reach (in my case 6 in the back of passenger side was easiest to reach) so you know what to expect from the others. If like mine yours have not been off since it left the factory, plan extra time just to get the coil pack connectors off.

Today’s scan showed torque management advance on both runs despite the changes in the tune to try to address it. I also have some misfires on cylinder 3, and the Manifold air temperature is not steadily dropping during WOT.

The misfires mean it is time to change the sparkplugs, regapping to a smaller gap due to the increased boost. The ATS-V LF4 is quite busy on top, so I will need to remove several things to get to the on-plug coil packs and plugs, but hopefully I can get that done soon.

The MAT trend means the charge cooler wants to be bled/vented again. I did that this morning, but will revisit a couple of times to try to ensure all the air in the system is replaced by new Dexcool coolant. I am surprised it needed doing again so soon, but I suspect in the heat the system expands and gulps in air now and then.

The continued TMA means that the changes in the tune for today were not successful, and back to the drawing board to try to sort out why I am getting TMA there, or simply table it for now. As I like to say, it bears more study. I plan to revert to the prior tune since today’s changes were not successful in addressing the TMA.

For today’s test I increased the pressure delta. One test (pictured) had no TMA at all (yay)

Boost comes right up, and torque is pretty flat. Cooler day, so almost SAE1349 conditions with a small correction factor of 0.2%.

The other test sample for today does show some TMA.

The rate of increase may be addressed now, but I note that the new TMA happens when Cylinder airmass exceeds 1.32. More study is needed; that is below the current tune knock airmass table. I suspect this is a 3rd source of TMA however.

This chart compares total cylinder airmass with boost and TMA