Old news:
My car has been consuming oil at the rate of 1 quart every ~250 miles.
I started experiencing a misfire, got the OBD2 code that it was cylinder 3, and pulled the plug. It was fouled and covered in oil. I replaced it with a champion plug. Car drove fine for about a thousand miles.
Cut to two weeks ago:
When things calmed down with work and family, I put the old plug back in, waited for the misfire to come back, and had it towed to the dealership. I also told them about the oil consumption.
The dealer replaced the plugs for free under Service Action S29842 and therefore didn’t think my misfire had anything to do with oil consumption (ugh). I got them to top off the oil so we could start down the oil consumption -> new pistons/rings path eventually.
3 days and 115 miles later, the misfire came back. I thought “Great, my plugs are fouling so quickly from oil that I might not have to bother with long oil consumption road.” Had it towed back to the dealer.
Turns out, not great. Dealer now claims I need TWO new coil packs because I now have 2 misfires and it has to be the coil packs because the plugs are brand new. I order them but tell them I will put them in myself (because I don’t believe my coil packs actually went bad).
I show up to the dealer on a Friday afternoon to diagnose my coil packs. I run my own OBD2 scan and it comes up as only 1 misfire (on cylinder 3 of course), not 2 (why did I need 2 coil packs?). I go to take out cylinder 1 (no misfire) and cylinder 3 coil packs to switch them. If the misfire doesn’t move from 3 to 1, I know the coil pack is fine. The bolt for coil pack 3 comes out really easily (uh oh). I switch them and go to bolt down coil pack 1 into cylinder 3 and the bolt wont catch. It just spins. Turns out, the mechanic must have cross threaded it during the plug change. So now I can’t run my test and have to leave it at the dealer so they can re-tap the threads. No car for the weekend and no further into figuring out my issue.
Monday, I get a call from the dealer that they re-tapped the thread, and did me a favor by putting the coil packs in (UGH!), but its still not running right. It’s still misfiring, but their scanner is saying the misfire is because of a bad ECM, not the coil packs. AND they are getting a code that the thermostat isn’t working. They call my warranty company and the warranty company says it will cover the thermostat, and to do that first before the ECM. This is where I am right now.
I don’t know what the heck is going wrong with my car, but since the thermostat is covered by my warranty, I authorized that repair. The service advisor says he had another car in recently with similar symptoms to mine and the thermostat didn’t fix everything and they had to end up replacing the ECM, so I should be prepared to do that repair too. Unfortunately, my warranty doesn’t cover the ECM, so I am going to be on the hook for over $1300 for a new ECM on an engine that is burning 1 quart per 250 miles before I even get a chance to deal with the oil consumption issue.
Anyway, why did I post this. I don’t know. I guess I’m just wondering if anyone else with a 4 cyl 2.0T engine had a thermostat or ECM go bad for them and what your dealer experience was, especially if you were out of warranty. I think 78,000 miles is pretty soon for stuff like this to fail. I am not claiming that the dealer is lying about what VIDA/DICE is telling them about my car, but I want to do my own diagnostics to see if I really need a new ECM. All these failures that started with fouled plugs and loose coil packs seem really coincidental to me. I’m not sure what other diagnostics I could do though. Any ideas?