What would cause a car that idles great to loose power when revved above 1200 rpm?

1994 MERCEDES BENZ S420L
186,000 MILES
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RAJAMES
  • MEMBER
  • 1 POST
car runs excellent until gas is pressed and car goes above 1200 rpm, then it struggles and chugs. checked exhaust,replaced both fuel pumps, checked vacume lines. think it may be a vacume sensor or electrical issue but not sure where to begin.
Oct 27, 2011 at 8:47 PM
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SQM
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 6,383 POSTS
Hello,

It sounds like it could be an issue with the throttle body. This vehicle is equipped with an electronic throttle actuator. Faulty circuits within the actuator can trigger drivability issues. It can impact the idle or the acceleration. As you try to accelerate the actuator sends incorrect signal to the ECM and that triggers fuel shutdown or reduced rate. That leads to low power.

On some occasions this can happen due to a dirty throttle actuator. The dirt and debris can impact the way the sensor sends signals to the ECM.
Cleaning out the throttle actuator can improve the drivability issue.

https://www.2carpros.com/articles/throttle-actuator-service

Please let me know if you have any questions.
Thank you.
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Jan 3, 2022 at 12:34 PM
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