2014 Q7 3.0T 74,000 miles. Under hard acceleration, car will fall back to idle but does not die and does not sputter. Remove foot from accelerator and press again and it resumes acceleration. Doesn't happen all the time, maybe two or three times a day. Cold or warm has no bearing on the issue. Last time it happened car was pulling good but only hit 3200RPM when it cut out. No codes. No alerts on dash. Car does not die, it simply drops to idle like you took your foot of the pedal. With my scan tool connected and my wife driving I had her duplicate the issue while I was checking commanded fuel pressure and actual fuel pressure. There is no change when it acts up. What else can I check in live data? Suggestions? Was thinking maybe accelerator pedal inputs but I don't see any changes in voltage on the pedal inputs either. Only other notable thing is taking off from a stop the car doesn't have much power unless you give it the beans. Either you take off like grandma or gun it. Car is new to me so I have no experience to compare it with. Wish it would just spit a code so I had some direction. My scan tool is pretty comprehensive. Autel Maxisys MK906BT.

 

Everything on this car is electronic; the throttle is actually fly-by-wire...it's actually a big sensor with a pedal attached to it. You can't press the brake at all while driving a Q7 or it will cut the throttle input completely, so there's couple things you can easily check right there...brake pedal position sensor/safety/security sensor is solidly attached/mounted, and you can also do a throttle pedal calibration/relearn, which doesn't require a scan tool. Between the two of those items it'll likely improve, if not resolve your issues, which are actually two separate issues most likely, IMHO. I'd also be checking the engine air filter is clean, so no obstructions to the airflow. Hit all the low-hanging-fruit items. For drivers who like to ride the brake pedal a bit while driving, this car won't play that game; it'll just cut the throttle until you get off the brake pedal fully.

You do wanna watch the DCR (Different Car Review Audi Q7) for this 4L Chassis to learn about the known issues on both the chassis and for your specific engine; one key takeaway is then need to change your oil at least every 6500 miles if not sooner...don't go by what Audi publishes. Likewise, none of the 'normal maintenance' a car requires on the driveline has ever been done on your used Q7, unless you've got physical receipts for it from a third party shop...Audi doesn't change those lubricants, ever, and wrote them out of the maintenance schedule. You don't have a ton of miles on it, so just put that on your radar for something you should do sooner (lubricants in the front/rear diffs, transfer case, transmission fluid/filter service) rather than later.

 

Man! You just lit a light bulb! My wife drove away the other day while I was standing in the yard on the phone with her. I asked if she had her foot on the brake and she didn't. Brake light was on. Gonna check that first thing in the morning. That would make sense that I would get no warning message or codes because the car is doing what it's supposed to do. Also the car was involved in a collision where the previous owner rear ended someone. That would be enough to jar that brake light switch loose. It had also knocked the fuel line off of the fuel pump in the tank. That one took a while to find! Thanks!

 

One day update. After adjusting the brake pedal switch it has not acted up. I will post again in a week or so.

 

Low-hanging-fruit; we like the free, DIY fixes.

Do the fly-by-wire throttle calibration too...it takes literally less than 30 seconds...no tools needed ; that one is usually a very impressive jump in throttle response off idle...gets the lag out.

 

Issue resolved! Thanks for pointing me in the right direction. I was going to repair/adjust the brake light switch since I had noticed it staying on. It would have resolved the problem but I would have never known the true culprit due to it's intermittent nature. Will do the calibration this weekend. Thanks again!