macpooh12

Have a ’04 SL500 R230 Roadster - a Florida car, always garaged, well maintained with 78,000 miles. The car was brought up to Massachusetts where it sat for 8 months (garaged). Now that it is back in use, it has developed a “roughness” when accelerating in lower gears but immediately stops once it shifts into a higher gear or when I let up on the gas. It is not a vibration but more like the engine is struggling for a few seconds, although there is no obvious sound of an engine problem. Ring a bell with anyone?

MBCO

If you have a scanner check for codes. Perhaps it’s a fuel problem? Was the tank filled and Stabil fuel preservative added? Sometimes condensation can buildup over winter and cause water in fuel that creates ignition issues and codes stored as a result.

seven_out

I'll speculate this is due to a dirty or failed mass airflow sensor (MAF). The theory is that when you accelerate the engine is abruptly drawing in considerably more air. If the MAF does not signal this change, then the mixture will briefly go lean and cause roughness until feedback from the lambda sensor causes a correction.

I would check the MAF with a $200 Star Diagnosis system or a generic OBD-II scanner which displays live sensor data.

macpooh12

Excellent, that makes perfect sense. Will do. Thanks so much for the information and suggestion.

macpooh12

Yes, stabilizer was added and it was in a heated garage. But I'll check codes as suggested - thanks much.