Even after the fuel treatment, I noticed the car still misfired at higher RPMs, except it wasn’t just at higher RPM. I realized that under any occurrence of boost, it would misfire slightly, depending on percentage of throttle.
So, full disclosure, after the initial breakdown, I bought the ignition coils on ebay by a third party manufacturer, non-OEM. I understand that many people have reservations for non-OEM parts, but I bought them because I have never had an issue with third party parts, and I also can’t afford OEM. After the fuel treatment didn’t seem to fix the problem, I started to blame the eBay brand ignition coils. My hypothesis was they could not provide the spark needed to properly ignite the fuel when boost is applied. Maybe they were designed and tested for the 3.2 I6 cars and not the 3.0T. Since I can’t afford new OEM, I bought the next best thing: used OEM.
After I installed the used, but OEM ignition coils, I went for a test drive. I did some semi-aggressive driving, and the car seemed to boost properly this time. The driving experience resembled how the car was prior to the whole ignition coil mess. 3 minutes later, heavy misfire, once again. This time, it did not stop. The car was running so bad in fact, I thought I did some permanent damage to the engine. I once spun a rod bearing on the 07 Prius I used to drive, and my S60 sounded and felt just like that. I go back home, re-installed the eBay brand ignition coils, the engine is running smoothly once again. I can breathe now.
Then, it hit me. The airbox lid was so loose, that the air filter was exposed. All the screws that were supposed to hold it in place were threaded. I go to the store, zip-tie the airbox lid shut where the screws would’ve been; now it is secure. Also, I installed a new air filter I’ve been meaning to put on. I go for a drive, and guess what? The intermittent jitters under boost is now gone. To be honest, I have yet to go WOT because I’m too afraid of something going wrong. That said, quarter throttle, half throttle applications where the car would’ve previously hesitated, or misfired if you would’ve stayed in it, the car is now boosting properly. All the same, it is a bit hard to tell since my tires are worn and unbalanced; I need to get new ones before I can make a definitive statement.
I’m still suspicious of the eBay brand ignition coils. I’m not fully trusting of them just yet, but my car is at least more than good enough to get by. I plan on buying OE coils down the line, but until then I believe I solved the issue with my car. What do you think?