RSQ3's MAP Sensor Causing Poor Performance & High Fuel Use

Had similar symptoms with my RS4 (2016) last summer. The engine performance issues and check engine light turned out to be a major vacuum leak, not a MAP sensor failure as initially suspected. The symptoms matched, poor fuel economy, sluggish acceleration, and rough idle. A qualified diagnostic revealed multiple failing gaskets around the intake manifold creating a substantial vacuum leak. The manifold absolute pressure sensor readings were off because of the leak, causing the engine management system to miscalculate fuel mixture. This was a serious issue requiring immediate attention, as continuous operation could lead to further engine damage. The repair involved replacing several gaskets and testing the MAP sensor, which was actually functioning correctly. The vacuum leak was allowing unmetered air into the system, throwing off all engine performance calculations. Would strongly recommend getting a proper vacuum leak test done before replacing any automotive sensors. Car sensors can show error codes when the actual problem lies elsewhere in the system. In many cases, what appears to be a sensor failure is actually caused by other underlying issues affecting the sensor readings.

Thanks for sharing that experience. My symptoms turned out to be quite similar, sluggish performance, terrible fuel consumption, and odd readings from the pressure sensor. I finally got it fixed last month and the car runs perfectly now. The intake manifold had multiple failing seals causing vacuum leaks, which were making the manifold sensor report incorrect readings. They fixed all the gaskets and tested the car sensors thoroughly. Just curious, do you remember roughly what you paid for the complete repair? Also, has everything been running smoothly since the fix, or have you noticed any other issues pop up?

Just wanted to follow up, after getting the vacuum leakage fixed, my car has been running flawlessly for months now. The total repair came to 235 Euro, which included replacing all the faulty gaskets and testing the MAP sensor system thoroughly. The manifold absolute pressure sensor was actually working fine, but those failing seals were causing it to send incorrect readings to the engine management system. Once the vacuum leaks were properly sealed, all the engine performance issues disappeared completely. No other problems have emerged since the repair. Fuel economy is back to normal, acceleration is crisp, and the engine runs smoothly at all speeds. Getting the vacuum leak diagnosed and fixed was definitely the right call, rather than just replacing sensors based on initial assumptions. The lesson learned was that sensor failure symptoms often point to underlying mechanical issues that need addressing first. A proper diagnosis can save both time and money in the long run.

Thanks for the helpful advice. After taking my car to a new mechanic, I got it properly diagnosed and fixed. The total repair bill came to 280 Euro, mainly for labor and new gaskets around the intake manifold. Like others mentioned, the automotive sensor readings were off because of vacuum leaks, not due to a faulty MAP sensor. The mechanic showed me the worn gaskets and explained how these leaks were affecting the manifold sensor readings and overall engine performance. The repair process took about 4 hours. They replaced all the gaskets, tested the manifold absolute pressure sensor, and ran several diagnostic checks to ensure everything was sealed properly. The difference in performance is remarkable, smooth idle, responsive acceleration, and fuel economy back to normal. This was definitely a better experience than my previous mechanic who just wanted to replace sensors without proper diagnosis. Sometimes getting a second opinion really pays off. The car has been running great for the past 3 weeks with no check engine lights or performance issues.