2014 Buick Regal GS,2.0L LTG turbo engine,74K miles
Hello everyone !! I’m having a rough idle felt most when the car is in drive and pressing on the brake.
No check engine light, but at one time had a P0171-00 pending code which never came back. It takes about 5 seconds once its put in drive with the brake depressed to start feeling it get rough. When its in Park, you can barely feel it.
Other than the idle issues the car runs fine, normal gas mileage as well. I do my own maintenance on the car. Spark plugs were changed at 55K and I just cleaned the MAF. I looked for vacuum leaks visually and with spray but found nothing. This car has a separate mechanical vacuum pump. To eliminate the possibility of a vacuum leak from the brake booster, as a test I removed the vacuum line to the check valve and plugged it, but the problem was still there.
Long fuel trims do not look good. I took 2 videos of live data from my scan tool so you can get an idea what I have.
If there is any other live data that can help with this please tell me and I will post it.
Thank You !
Not sure if this will help understand the issue more but came across a TSB that might help. I’ll post it below. There are other TSBs related to rough idle but are accompanied with check engine light codes. The TSB#16-NA-383 refers to carbon build up on the valves.