Audi Q5 Rough Idle: Injectors and Plugs Could Be Culprits

I had a similar issue with my 2015 Audi Q3 2.0 TFSI. With some experience working on cars, I initially thought it was related to fuel injectors, but it turned out to be an exhaust leak near the manifold. The symptoms were almost identical, rough idle, engine misfire during acceleration, and check engine light. The engine would run really uneven, especially when cold. Had it checked at a workshop where they ran diagnostics and performed a smoke test to locate the leak. The exhaust leak was causing incorrect readings from the oxygen sensor, which made the engine run rich at times. Total repair cost was 265 Euro including parts and labor. Before you head to the workshop, it would be helpful to know: Current mileage on your Q5? When was the last time you had spark plugs replaced? Are you noticing any unusual exhaust smell? Does the problem get worse when the engine is cold or warm? The crankshaft sensor readings might also be worth checking as they can cause similar symptoms. With proper diagnosis, this should be fixable without major issues.

Last service was done at 165000 KM and current mileage shows 168323 KM. The problems getting worse when the engine is warm. My ignition coils were replaced during the last service, but no work was done on the oxygen sensor or fuel system. The engine misfire seems most noticeable when the engine is under load. After checking my service records, the spark plugs were changed about 45000 KM ago. I notice the rough idle gets particularly bad after the engine has been running for about 15 minutes. No unusual exhaust smells that I can detect, but fuel consumption has increased noticeably in the past month. I have scheduled a diagnostic check for next week. The technician mentioned they will look at the fuel pump and run a complete system scan.

Thanks for the additional details about your Q5. Those symptoms match what I experienced before finding the exhaust leak on my Q3. Since your issue worsens with a warm engine and under load, this does sound very similar. However, given your mileage and the fact that ignition coils were recently replaced, I would suggest having them check the fuel injectors thoroughly. When my engine misfire issues started, the diagnostic scan pointed to multiple cylinders, which can indicate fuel delivery problems rather than ignition issues. The air filter might also be worth checking, a clogged one can cause similar symptoms, especially the poor acceleration under load that you mentioned. The increased fuel consumption you noted often points to either a fuel system issue or air-fuel mixture problems. The complete system scan is definitely the right approach. Make sure they check: Fuel pressure at the rail, Air filter condition, Injector spray patterns, Exhaust system for leaks In my case, fixing the exhaust leak resolved most issues, but I also ended up replacing two fuel injectors that had developed partial blockages. The total repair brought the engine back to running smoothly with no more misfires or jerking during acceleration.

Thanks for all the suggestions. After reviewing the symptoms and your experiences, I'm getting a clearer picture of what might be wrong with my Q5. The rough idle and acceleration issues do sound similar to what you encountered. Since my ignition coils are new but spark plugs are getting up there in mileage, I will ask them to check those first. The increased fuel consumption and problems under load make me think the oxygen sensor might need attention too. Makes sense about the air filter, I actually cant remember when it was last changed. I will make sure they check all the points you mentioned during the diagnostic scan, especially the fuel pressure and injector patterns. The fact that the problems get worse with a warm engine is definitely something I will highlight to the technician. Good to know about the potential exhaust leak connection, will have them do a thorough check of the exhaust system as well. Hoping it turns out to be something straightforward like your case and not a major repair. Will update once I get the diagnostic results next week.