Smart ForTwo EGR Valve Failure Causing Performance Drop

Had similar symptoms on a Smart ForTwo (2007) with the 1.0L gasoline engine. The rough idle and power loss were identical issues, combined with excessive fuel consumption. Initial diagnosis revealed the EGR valve was stuck in a partially open position, causing inconsistent air-fuel mixture and affecting vehicle emissions. A thorough inspection showed carbon buildup had jammed the EGR valve. The vacuum lines connected to the EGR system also showed signs of deterioration, leading to vacuum leaks that contributed to the erratic performance. The automotive repair involved removing the EGR valve, cleaning the carbon deposits, and replacing damaged vacuum lines. This was a serious issue requiring immediate attention since a malfunctioning EGR system can lead to engine damage if left unchecked. The repair also included cleaning the intake manifold, as carbon deposits typically spread throughout the system. The symptoms you describe strongly suggest EGR valve issues. When booking a mechanic appointment, request a complete EGR system diagnostic. A qualified technician should check both the valve operation and related vacuum lines, as these components often fail together in these engines.

Thanks for sharing your Smart ForTwo experience. Your symptoms match what I was seeing with my ForTwo exactly. I went ahead and had it checked, turned out you were spot on about the EGR valve and vacuum lines. The check engine light triggered because of the recirculation issues, which explains the black smoke. The mechanic found heavy carbon buildup just like in your case. They had to do a complete clean of the EGR system and replace a couple of deteriorated vacuum lines to get the proper gas flow back. The diesel engines supposedly have these problems more often, but our gas engines arent immune either. Quick question: do you remember roughly what you paid for the full repair? Also, has everything been running smoothly since the fix or did you notice any other issues pop up later? Just want to make sure Im watching out for the right things going forward.

The full repair on my Smart came to 355€, which included replacing the faulty EGR valve, cleaning the system, and fixing the vacuum lines. After the fix, the car has been running perfectly with no check engine light or rough idle issues. The fuel economy returned to normal, and the black smoke completely disappeared. The automotive repair solved all the initial problems, and the engine now maintains steady performance without any power loss. Its been several months since the EGR valve replacement, and I havent noticed any related issues. The vacuum lines are holding up well, and theres no more hissing sound during acceleration. Regular maintenance has helped prevent carbon buildup from returning. If you keep an eye on engine performance and address any rough idle symptoms early, you should avoid future EGR system problems. The repair was definitely worth the investment, considering the potential engine damage that could have occurred if left unfixed.

Following up after the repairs. Like you mentioned, it was definitely the EGR valve causing trouble. The total bill came to 410€ for the full job, cleaning out the carbon deposits, replacing the valve itself and fixing those worn vacuum lines. The mechanic showed me the old parts and wow, the carbon buildup was pretty bad. Got to say, what a difference the repair made. The engine runs so much smoother now, no more black smoke during acceleration, and fuel consumption is back to normal. The emissions test they ran afterward showed everything working properly. That annoying hissing sound is completely gone too. The mechanic mentioned these EGR problems are fairly common in these engines once they get some age on them. They recommended regular engine cleaning to prevent carbon deposits from building up again. Been about a month since the fix and the car feels like new, definitely worth every cent to get it sorted properly rather than letting it get worse.