Escalade Diesel's Power Loss & Hissing Points to Manifold

Had similar symptoms on a 2020 Cadillac XT6 diesel. The intake manifold control flap malfunction severely impacted engine performance and airflow control. Main symptoms matched exactly: power loss, hissing noise from the intake system, increased fuel consumption, and rough running. The engine control unit repeatedly triggered warnings due to incorrect air-fuel mixture. The issue required a complete intake manifold replacement because the control flap mechanism had failed. This was a serious repair as the intake system manages crucial airflow distribution between cylinders. Running the engine with this fault risks further damage to other components. The repair involved: Full diagnostic scanning, Intake manifold removal and replacement, Control module recalibration, Air intake system cleaning, Multiple test runs to verify proper operation Without repair, the reduced power and excessive fuel consumption would have continued to worsen. The jerking during acceleration happens because the engine management system tries to compensate for incorrect air distribution. Important to address this promptly to prevent additional engine damage and restore proper performance.

Thanks for the detailed advice. You perfectly described what I am experiencing with my Escalade. The engine misfire and reduced power are really concerning. I scheduled a repair appointment for next week. My mechanic also mentioned the intake manifold might need replacement. Did you keep track of the total repair cost? Also wondering if you had any other issues pop up after getting it fixed?

Finally got the repair done last week and can confirm the intake manifold flap control issue has been fully resolved. The total came to 465€ for replacing the defective intake manifold control switch. The engine performance is back to normal with no more power loss or hissing sounds. Fuel consumption has significantly improved and the engine light has stayed off since the repair. The air intake system is working perfectly now with no misfires or jerking during acceleration. No additional problems have surfaced after the fix. The mechanic did a thorough job testing everything post-repair to ensure the flap control was operating correctly. The engine runs smooth and quiet now, just like it should. Make sure your mechanic checks the entire air intake system while doing the repair. A proper diagnosis and complete testing afterward are essential for preventing any recurring issues with the manifold flap control.

After dealing with that frustrating manifold flap issue, I finally got my Escalade fixed last Thursday. The mechanic confirmed exactly what you mentioned, a faulty intake manifold was causing all those problems. The repair took about 4 hours. They replaced the entire intake manifold assembly and recalibrated the airflow control system. The total damage was 890€, but honestly worth every cent considering how the car runs now. No more engine misfire, hissing sounds, or jerking during acceleration. The difference in performance is like night and day. Fuel consumption is back to normal, and that annoying check engine light hasnt shown up since. Really glad I didnt wait longer to get it fixed. Only wish Id known about this common issue earlier. Would have saved me weeks of stress and probably prevented some extra wear on the engine. At least now I know what to watch out for in the future.