I did a cleaning today with Seafoam Motor Treatment, Seafoam Spray, and SeaFoam DeepCreep (not all used to empty of course haha). I followed the updated methodology in the main post. I modified it from a question into just a 'method for future readers that happen on it.
Before I started the treatment, I took off the throttle body to take a peak inside the intake manifold. The most popular cleaning guide on this
Camaro5 forum is one of the V6 LFX and it was in a pretty bad shape. Based on all the Youtube videos I saw and online forum posts I read (all of different vehicles), I was preparing to be shocked.
Well I pulled the bolts and plug and took a look inside. Wow, the throttle body and intake manifold was actually...nearly spotless. The throttle body + plate obviously had some dark carbon residue on the edges of the plate and housing but nothing that was bad. I broke open the seal on the SeaFoam DeepCreep and did a cleaning, soak, and removal of the carbon on the throttle body/plate.
The intake manifold itself, had a shine on the inside which is to be expected but what surprised me was that it looked like it was plastic. The intake manifold uses some black 'painted' metal which made it seem so. The shine, manifold color, and clean nature of the inside looked like the plastic on the stock air intake with WD40 sprayed on it.
I only wanted a cleaning and didn't want to spend the time to take it apart and check out the valves or cylinders. They could be in worse condition but I wasn't about to do any extreme carbon cleaning past the SeaFoam I was about to give it.
As for the actual cleaning, I already had Chevron Complete Fuel System Cleaner in my tank from the week before when my tank ran dry and I dumped it in and put 10gallons on top of it. I always run 93 premium of course and did a fuse pull to reset fuel type a few weeks ago.
Past that, I did the cleaning as outlined above in the updated methodology with an assistant on the pedal. Got a smoke show for a minute but not much past that.
What changes did I feel after doing it?
I unfortunately can't provide an objective answer I am comfortable with as an engineer. Today was the first warm day I got to drive my car in over 2 weeks. The past few weeks of driving were in groggy and cold weather and doing short 7minute drives. Those didn't have a linear power response probably due to outer temperature, cold road in contact with tires, and an engine that wasn't fully warmed up. It was very peaky and either went V4 AFM or full on beast mode once it 'caught'.
Today, I also discovered Competetive Mode and drove in that all day post cleaning. This made me drive it in an active fun way where I'm using the S mode and paddles and driving it like it's meant to be driven. In all the other situations for the winter, it's been mainly conservative, and passive. And.... did I mention that I brought it to the exhaust shop right after the cleaning to do a muffler delete?
Those make for probably the largest change of variables you can think of when trying to compare pre to post performance. On a subjective level though, I thought that maybe the throttle was more responsive and linear such that it didn't grog and then go WHAM but performed as it should throughout the range.
Overall, very happy with the cleaning as it taught me more about my car and gave me future experience with repeating this procedure.