Smart Fortwo Turbo Boost Issues Killing Performance

I experienced nearly identical symptoms with my Smart Forfour CDI from 2014. The whistling sound and poor performance turned out to be a faulty wastegate valve in the turbo system. The diagnosis showed the wastegate was stuck partially open, preventing proper boost buildup. This explained the significant power loss and increased fuel consumption, as the engine tried compensating for the low boost pressure. The check engine light came on because the MAP sensor detected inconsistent pressure readings. The repair required removing the turbo assembly to replace the wastegate actuator and its control mechanism. This is definitely not a DIY job, it needs specialized tools and proper calibration after installation. This is a serious issue that will progressively worsen if left unattended. A failing wastegate can eventually lead to complete turbo failure or engine damage. The intercooler system also needed inspection to ensure no damage occurred from the irregular boost pressure. Best approach is getting a proper diagnostic scan first. The fault codes will help pinpoint if its truly the wastegate or potentially something simpler like boost sensors or vacuum lines.

Thanks for sharing those details about your wastegate issue. My situation was indeed very similar! The mechanic managed to fix it following pretty much the same diagnosis path you described. Would you mind sharing roughly how much the total repair cost? Also wondering if youve experienced any other boost pressure or turbocharger related problems since getting it fixed? Its always helpful to know what to watch out for with these turbo systems.

The total repair bill came to 860€ for the wastegate valve replacement and recalibration of the boost control system. It was worth every cent as the turbocharger now performs perfectly, with no turbo lag or power issues. Since fixing the bad boost pressure system last year, the car runs like new. The fuel economy returned to normal and that annoying whistling completely disappeared. The pressure sensor readings are now stable and the engine maintains proper boost across all RPM ranges. One tip: regular oil changes with the correct grade oil are crucial for turbo longevity. Clean oil keeps the turbocharger bearings well lubricated and helps prevent similar issues from developing. The throttle body also stays cleaner when the entire boost system is working correctly. Best news is the check engine light hasnt returned and the engine maintains consistent power. These turbo systems are actually quite reliable when properly maintained and promptly repaired if issues arise.

I took your advice and finally got my Smart fixed last week. After getting a proper diagnostic scan, it turned out you were spot on, the wastegate was the culprit. The total came to 920€, which included replacing the wastegate and checking the entire turbocharger system. The mechanic I found was really thorough. They showed me the faulty parts and explained how the boost control system works. They even spotted and fixed a small vacuum leak that was contributing to the turbo lag. Since the repair, the check engine light has stayed off and the engine feels strong again. The whistling noise is completely gone and fuel consumption is back to normal. MAP sensor readings are now stable according to their final diagnostic check. Been driving it for a week and the turbocharger response is crisp, no more hesitation or stalling. Thanks for helping me understand the issue before visiting the shop. Being informed definitely helped me communicate better with the mechanic and understand the repair process.