artrichter001

Hello folks, I have been doing a lot of research throughout the forums to see if I can dtermine whats casuing my issues, to no avail.


I own a 2013 Q5 (2.0T FSI) with a little over 39k miles. The problem I am experiencing is the following. When driving the car, and coming to a stop, just as I release my foot from the pedal and the RPM get down to ~ 900, my car begins to stutter and the RPM begins to jump from what appears to be the normal idle speed (900 RPM) down to around 600 RPM and back up again in a infinite loop. Obviously, all the car begins to shake feeling as if it is about to stall (but never actually does).


No CEL light is on.


I have read a lot of posts with similar problems and blaming the following:

• PCV Valve
• MAS
• Vaccum leak
• Ignition Coil(s)

The thing here is that all posts I have found relate to the issue being present at Idle. My car Idles just fine when coming to a complete stop (by applying the brake). My issue seems to be more frequent when the car is rolling down (ie going down a ramp). I'm experiencing no rough idle at startup, by the way.


One more thing, I recently changed a faulty O2 sensor and this problem appeared a couple days later.


I know that there are a lot of options to determine what is cousing this, but I would like to get opinions on these before I begind changing out expensive parts!


Thanks for your input!

thomascw

Do you have access to a code-reader/scanner? Even if the CEL didn't come on, there should be a code stored indicating a possible cause if a part is malfunctioning. Maybe the new O2 sensor(ex. bad reading causing a rich/lean swing in the mixture when you take your foot off the accelerator).

Did you change the sensor yourself, or have a shop do it? If a shop, then you should return to them as they should be dealing with the sensor if it is a dud and needs replacing(warranty for defect) or should own that they didn't fix the original issue if that is the case.

Same goes for the part if you did it yourself, take it back to the retailer and have it replaced if you determine that to be the case. A scanner will help to show that it is a dud, if so.

All of those suggested causes from the forums make sense, and you may end up having to test each if the O2 sensor isn't the issue.

Sorry to hear about the trouble.

artrichter001

Thomas, thank you for your reply. Fortunately, the issues were related to the new O2 sensor. I was given a different part number and the sensor, although identical in shape, is different on the inside.