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paulbescondido

paulbe ... 2/6/2019

2011 Mercedes Benz C300 Sport 6 Cyl 3.00L

Transmissions & Drivetrains

Why intermittent/occasional sluggish or vibration

THE CAR IS 6-CYLINDER 3.0 V6. 145,000 MILES (NOT 4 CYL 2.6L)
THIS HAPPENS MOSTLY WHEN ACCELERATING GOING UP HILL. EVEN ON FREEWAY IT SOMETIMES DOES THIS. THERE IS NO FAULT CODE (MISFIRE) OR EVEN TRANSMISSION CODE. I ADDED SOME FUEL
INJECTOR CLEANER TO 12 GALLONS OF GAS. NO CHANGE. I CHANGED VERY OLD SPARK PLUGS. NO CHANGE. IT JUST PASSED SMOG TEST. I KNOW A VERY GOOD REPAIR SHOP BUT I WANT TO ASK IF:
(1) SLIPPING TRANSMISSION (2) BAD ENGINE MOUNTS (3) DIFFERENTIAL PROBLEM (4) IN-TANK FUEL FILTER CLOGGED (NEVER BEEN CHANGED) (5) BAD VALVE (CARBON BUILD-UP)

3 Answers


Jimm

Jimm 2/8/2019

First step - have the stored fault codes or check engine light scanned - for free - at any local auto parts store; Advance Auto, Auto Zone, NAPA.
Then, post a reply as 'add answer' with the specific code for more assistance.

This aspect is important; there may be a fault code stored in the OBD memory which may not be displayed as a check engine light.

Do not skip this important first step - there are literally hundreds of possible fault codes. Avoid wasting/ throwing money at the problem.

Possible Causes of Engine Hesitation or Stumble:

Dirty fuel injectors (cleaning the injectors often fixes this)
Dirty air filter (change filter)
Dirty / clogged fuel filter (change filter)
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

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Jimm

paulbescondido 2/10/2019

Add answer. No check engine light or stored fault codes

Jimm

Jimm 2/10/2019

That good - first step accomplished. Then, check the other items on the list, beginning with the least expensive; cleaning and inspecting the air intake, air filter; check and fix any engine vacuum leaks; and proceed down the list - filters first.

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Jimm

Jimm 2/10/2019

Try these online resources; www.autopartswarehouse.com, www.rockauto.com, www.partsgeek.com - to list only a few.

In fact, they (RockAuto) list the replacement intake air filter from around $4.60 each, and the ignition coils from around $20.00 each for your vehicle.

Air intake filter = BOSCH part #5275WS - or it's equivalent
Ignition coil (coil-on-plug) = √úRO PARTS #2729060060 - or it's equivalent

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