We had a wedding in the family this weekend. It was in state, but still about an hour away. I drove the gray car to the hotel, and drove the green one home. This was a good thing, because it gave me a chance to spend a little highway time with the green car before removing the license plates. Both cars came back to my house together the next day.
These cars are like fraternal twins; they have nearly identical specs, but very different personalities.
The green car has been around the block a few times, but man, that engine is sweet.
The gray car is much prettier, but I was still fighting with the idle. It drove perfectly and wasn't throwing any codes, but it just didn't feel right with the throttle closed. It was very subtle, and I might not even have noticed it if I didn't own two cars with the same engine, but it was there.
I decided to fire one last shot at the gray car with the parts cannon. I had another new set of spark plugs on the shelf, and this time, I skipped the copper anti-seize on the threads. I followed that up with a new upstream oxygen sensor for the 1-2-3 cylinder bank. The front bank (4-5-6) had gotten a new sensor at the shop a couple of weeks ago.
Breaking the old O2 sensor loose wasn't much of a problem with the engine at full operating temperature, but getting the electrical connector apart was a bit of a PITA. Access to the rear bank of cylinders was much better after I removed the factory shock tower brace and the little heat shield between the exhaust manifold and the coils. Once I could get in there a little easier, I was able to remove the plug from its bracket, and then disconnect the wiring. Installation was the reverse of removal.
With the last of the new parts installed, I used the Launch scanner to clear the throttle position sensor memory again, and performed the steps to reset the learning value.
This time, the idle is finally as smooth as it is in the other car.
One final tankful of premium and the gray car is headed home with WK1.