S7 Poor Performance and Rich Fuel Mix Symptoms Fix

Using my experience with a 2018 S5 that showed similar symptoms, this sounds like failing fuel injectors, a fairly serious issue that needs prompt attention. The check engine light combined with rough running and high fuel consumption matches what I encountered. The symptoms you describe, especially running rich and jerking during acceleration, strongly suggest faulty injectors that are likely stuck open, dumping excess fuel into the cylinders. My car exhibited identical behavior before diagnosis confirmed multiple failing injectors. The repair required replacing two injectors and cleaning the others. The oxygen sensor readings were also affected due to the rich fuel mixture, which explains your power loss. A proper diagnosis will involve checking fuel trim values and performing injector leak-down tests. This isnt a job for DIY repair due to the precise calibration needed when installing new injectors. The fuel system requires specialized tools and equipment to properly test and replace components. While getting multiple opinions is smart, delaying repairs risks damaging your catalytic converter from the excessive fuel. The rich condition will continue degrading engine performance and fuel economy until addressed. The age and mileage of your S7 align with typical injector wear patterns, especially if previous maintenance was irregular. Consider having all injectors replaced as preventive maintenance since they tend to fail progressively.

Thanks for the detailed response about the injector issue. My check engine light started flashing again last week, and the intake manifold pressure readings are all over the place. The rough running got even worse, especially at idle. Did you remember the total repair cost for your injector replacement? My fuel economy is now terrible, burning almost double the usual amount. Also wondering if you had any other problems crop up after fixing the injectors? The air filter and oxygen sensor readings seem fine according to my scanner, but Im worried there might be related issues Im missing. Really want to avoid multiple shop visits if possible. Planning to take it in next week but would appreciate knowing what numbers to expect.

Had my S5 fixed last month and the rich fuel mixture issue is completely resolved now. The repair involved replacing a faulty fuel injector that was stuck partially open, causing the air-fuel ratio to go way off. Since the fix, the engine runs smoothly with no more jerking or rough idle. The total cost came to 515 Euro for parts and labor, which included testing and calibrating the new injector. The shop confirmed the oxygen sensor readings normalized after the repair, and fuel economy returned to normal within a tank of gas. No additional problems emerged after the repair. The engine management system adapted to the new injector quickly, and all manifold pressure readings stabilized. My fuel consumption dropped back to normal levels once the air-fuel ratio was corrected. With your symptoms being so similar, focusing on the fuel injectors is the right approach. The flashing check engine light and poor fuel economy strongly suggest a similar injector issue. Getting it addressed promptly will prevent potential damage to other components.

I finally took my S7 to the shop last week after getting worse fuel consumption and that annoying jerky acceleration. The check engine light kept flashing and the car was running terribly rich. Turns out it was exactly the injector problem you mentioned. The mechanic found two faulty injectors that were dumping excess fuel. Total bill came to 890 Euro including parts, labor and testing. They also noticed my air filter was pretty clogged which wasnt helping the air-fuel ratio issues, so I had that replaced too. After the repair, the engine runs perfectly smooth again. No more jerking or rough idle, and my fuel consumption is back to normal. The intake manifold pressure readings have stabilized and the oxygen sensor shows everything running correctly now. Really glad I got it sorted before any other components got damaged. Thanks for helping me avoid getting overcharged, the repair cost was right in line with what you mentioned for similar work.