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Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 28793
Experience:  Over 15 years experience as a Mercedes dealer technician
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1995 S500 run good when idling.give it gas and it fall on

Customer Question

1995 S500 run good when idling.give it gas and it fall on its face. check engine light is on
JA: Does the light stay on, or does it blink?
Customer: it stay on
JA: Are you fixing your S500 yourself? What have you tried so far?
Customer: no its in the shop
JA: Anything else you want the mechanic to know before I connect you?
Customer: they say it has to be acting up when they check it
Submitted: 11 months ago.
Category: Mercedes
Expert:  Pete replied 11 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Was the shop able to check the fault codes since the check engine light was on and if so what codes are set?

Let me know so we can continue,thanks Pete.

Customer: replied 11 months ago.
you lost me in left field. I just wanted ans.
Expert:  Pete replied 11 months ago.

O.k.,since the check engine light came on the shop or a dealer should be able to plug in their scan tool/computer into your vehicle and read what failure codes are set in the computer for this issue.The engine computer has detected a problem and has turned on the check engine light and having the code read out will help diagnose and repair this here.There are several components that can act up and cause a fault like this here so having the codes read out will help in pinpointing the cause here.

Since it does start and run but falls on its face when the gas pedal is pressed this sounds like a weak fuel pump intermittently lowering fuel pressure causing the stall out or an issue with a restricted fuel filter.The fuel system would need to be tested to see if the pump and filter need replaced.

The other issue I have seen intermittently is a fault with the mass air flow sensor needing replaced.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete