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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53901
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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E320: I have an 04 E320 and it hesitates and jumps when accelerating

Customer Question

I have an 04 E320 and it hesitates and jumps when accelerating during first 15 minutes of operation and sometimes when warm as well but not on highway at higher speeds after warming up. Is this fuel pump or injector issue or other? I have had plugs replaced and other work but nothing seems to solve issue. Engine light is sometimes onfir a few days then off for a few days. During warm weather I also get an error message that gas cap not secured?
Submitted: 2 years ago.
Category: Mercedes
Expert:  Marty replied 2 years ago.
Hi, for a problem like this I would suspect a bad mass air flow sensor or one or more bad ignition coils. The sensor is more likely to be the problem as it can act up cold and then work ok once the engine warms up. Ignition coils would tend to act up all of the time. I don't think this is a fuel pump or injector issue. I'd get the car scanned for fault codes. Most likely there will be codes stored for incorrect fuel mixture which would usually point to a bad mass air flow sensor. Your gas cap message could simply be due to a bad cap or a leak in the fuel tank evaporative system but it will not affect the engine running.
Let me know if you have any questions.