SQ7 Diesel Manifold Symptoms Point to Intake Failure

Had the same symptoms on my Q8 50 TDI (2017) last summer. The check engine light and rough running were identical to what you describe. After proper diagnostics, it turned out the intake manifold had developed hairline cracks from heat stress, causing significant vacuum leaks. The manifold pressure sensor readings were inconsistent, which directly impacted engine performance and caused the misfires. The exhaust smell you mention is typical of a leaking intake manifold, as the engine runs rich trying to compensate for the vacuum leak. This is definitely a serious issue requiring immediate attention. Continued driving risks further engine damage and decreased fuel efficiency. The repair involved complete manifold replacement, including new gaskets and sensors. The job requires specialized knowledge of these engines, particularly the high-pressure fuel system and intake architecture. A qualified shop needs proper diagnostic equipment to accurately measure manifold pressure and identify leak points. Given the complexity of modern diesel engine management systems, this is not a job for general repair shops. Suggest finding a specialist who regularly works on these engines rather than risking further complications with inexperienced mechanics.

That sounds exactly like the problem I dealt with on my SQ7 a few months ago. The vacuum leak symptoms match perfectly, from the engine misfire to the rough idle. My car also had those manifold pressure readings jumping all over the place. After getting it fixed I noticed a huge improvement in engine performance, and the exhaust smell disappeared completely. Just curious, do you remember what was the total cost for your repair? Also, has everything been running smoothly since the fix? I had to get some additional air intake work done a few weeks after, so wondering if you experienced any related issues.

Thanks for the follow-up. Since getting the intake manifold fixed last summer, my Q8 has been running perfectly with no check engine lights or engine misfires. The manifold sensor readings have stayed consistent, and the vacuum leak was completely resolved. The total repair cost was 1180 Euro, which included replacing the defective intake manifold that had developed scorching damage. It was expensive but worth every cent considering how the engine performance returned to normal. Unlike your situation, I have not needed any additional air intake work. The initial repair addressed all the manifold-related issues completely. The shop did a thorough job checking all connected components while they had everything apart, which probably helped prevent any follow-up problems. The improvement in performance was immediate, no more rough idle, stalling, or that concerning exhaust smell that typically indicates vacuum leaks. Fuel efficiency also returned to normal once the engine could properly regulate air intake again.

Finally decided to get my SQ7 fixed after putting up with those manifold pressure issues for too long. Found a specialized shop that really knew their stuff. The mechanic spotted the cracked intake manifold right away during diagnostics, no wonder the check engine light kept coming on. The repair took two days but made a massive difference. Total bill came to 1350 Euro for the new manifold, gasket replacement, and labor. Looking back, I should have done it sooner instead of risking more engine damage. Had to go back after three weeks when I noticed some air intake noise, but that was just a loose clamp they fixed under warranty. Since then, the car runs like new, no more misfires, stalling, or that nasty exhaust smell. The engine performance is back to what it should be, and the manifold sensor readings are staying steady. Really glad I found a proper specialist instead of going back to my regular mechanic. The expertise made all the difference in getting it fixed right the first time.