I have searched through the forums, and there are so many of the same symptoms with different results that I wanted to just ask an opinion before I start replacing parts, or take it to my local VW shop.
I have a 2007 Passat Wagon, 2.0 FSI engine. 113k miles, bought recently at 112k miles. Few weeks after buying, it started throwing a P0299 code. My OBD2 wouldn't read it, so I took it to Autozone. Readout was Turbo/ Super charger underboost. Explanation: faulty wastegate bypass regulator valve. When I looked underneath I saw that the bypass valve had oil all over it, so after research on the forums I assumed the gasket inside had gone out.
Yesterday I replaced it with this one from Amazon, and verified that the old one was damaged.
Took it for a drive, significant improvement in boost and not as much lag on acceleration. Also the whistling noise I'd hear coming from the turbo was no longer pronounced.
Filled it up with gas and went on an interstate drive last night. After a bit, I noticed that the car seemed to be misfiring when accelerating in a high gear and downshifting. It got worse and the check engine light started to flash while the car seemed to shudder. I eased off and the check engine light went out. Tried to baby it, but every time I'd go up a hill or put some torque strain on the engine, it would start misfiring. It did it mostly in a high gear, but also did it once in 3rd gear while climbing a slight incline at a low speed. One the way back home, the check engine light came on solid again. My reader said the n/a message again for the pending codes.
Brought it home and parked it to do some research. Some of my thoughts so far are:
- faulty bypass valve. I bought the one recommended on a forum post, but wondered if there was something about it that would be triggering a misfire? Why would it only do it under acceleration?
- bad ignition coils. This seems rather likely based off the symptoms and what I've seen on the forums, but it does seem weird that it would have happened right after doing the bypass valve. They could of course be completely unrelated.
- bad gas or gas cap not tight. Seems unlikely, but I did read some people had some random misfire issues for these reasons. I used the same gas I normally use last night - I checked the gas cap last night but obviously there's not really a way to know if it was 'clicked' since it clicks once every time you twist it to the right on this car. Was thinking of taking it for another drive after checking the gas cap just to rule out something really dumb, but not sure if that's wise to test.
What do you all think? Should I replace coil packs as a preventative and then take it for another drive, or something else? Any possibility it's still related to the bypass valve?
Thanks for any insight.
I have a 2007 Passat Wagon, 2.0 FSI engine. 113k miles, bought recently at 112k miles. Few weeks after buying, it started throwing a P0299 code. My OBD2 wouldn't read it, so I took it to Autozone. Readout was Turbo/ Super charger underboost. Explanation: faulty wastegate bypass regulator valve. When I looked underneath I saw that the bypass valve had oil all over it, so after research on the forums I assumed the gasket inside had gone out.
Yesterday I replaced it with this one from Amazon, and verified that the old one was damaged.
Took it for a drive, significant improvement in boost and not as much lag on acceleration. Also the whistling noise I'd hear coming from the turbo was no longer pronounced.
Filled it up with gas and went on an interstate drive last night. After a bit, I noticed that the car seemed to be misfiring when accelerating in a high gear and downshifting. It got worse and the check engine light started to flash while the car seemed to shudder. I eased off and the check engine light went out. Tried to baby it, but every time I'd go up a hill or put some torque strain on the engine, it would start misfiring. It did it mostly in a high gear, but also did it once in 3rd gear while climbing a slight incline at a low speed. One the way back home, the check engine light came on solid again. My reader said the n/a message again for the pending codes.
Brought it home and parked it to do some research. Some of my thoughts so far are:
- faulty bypass valve. I bought the one recommended on a forum post, but wondered if there was something about it that would be triggering a misfire? Why would it only do it under acceleration?
- bad ignition coils. This seems rather likely based off the symptoms and what I've seen on the forums, but it does seem weird that it would have happened right after doing the bypass valve. They could of course be completely unrelated.
- bad gas or gas cap not tight. Seems unlikely, but I did read some people had some random misfire issues for these reasons. I used the same gas I normally use last night - I checked the gas cap last night but obviously there's not really a way to know if it was 'clicked' since it clicks once every time you twist it to the right on this car. Was thinking of taking it for another drive after checking the gas cap just to rule out something really dumb, but not sure if that's wise to test.
What do you all think? Should I replace coil packs as a preventative and then take it for another drive, or something else? Any possibility it's still related to the bypass valve?
Thanks for any insight.