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MB Paul
MB Paul, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3567
Experience:  Qualified Mercedes Benz Diagnostic Technician - 20+ years experience - Workshop Foreman for Mercedes
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Marty, I have a merc e320 with M04 engine which will not

Customer Question

Hi Marty, I have a merc e320 with M04 engine which will not always idle properly (feels like its running rough) it's been serviced as per schedule all its life and new plugs make no difference...could it be a faulty coil pack? David
Submitted: 2 years ago.
Category: Mercedes
Expert:  Lou P. master tech replied 2 years ago.
Hello my name is ***** ***** i will do my best to help you , i strive for EXCELLENT service and nothing less. Do you have a check engine light ? Most times the fuel pressure regulator fails and leaks excess fuel into the vacuum lines. Pull the line off and see if there is wetness inside. If you do not know what the fuel pressure regulator is let me know and I will upload a photo. Lou

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