Question about a 2003 CLK 430 (C208)?

Question

My mother is looking a 2003 CLK 430. I looked at it and drove it today, so I could give my input/opinion on the car, and noticed something that gave me pause about the car. When accelerating from a dead stop I noticed that there was some hesitation. The seller mention that he been using regular fuel in it, I believe the car is suppose to use premium. So I'm speculating that the when a load was placed on the engine, the ECU may have pulled some timing, which may have caused the hesitation. Also the car seemed to be slightly down on power compared to what I was expected, not a huge amount, but I was sort or expecting a 275 HP car to pull a bit harder under WOT. The seller didn't know when the last time the car had a major service (spark plugs, filters, etc.) so that may have been part of it as well. The car has 105k miles on the clock. Steering and suspension seem as tight as a drum, body is flawless, paint is very good, everything works, seats only have minor wear, etc. Overall I'd say the car is in very good shape for its age. It's been checked out by a MB shop and given a clean bill of health, but the hesitation has me concerned. I'd appreciate anyone's input on the matter, thanks in advance.

Update:

Added:

There's no engine fault light on that would indicate an issue with the MAF sensor/02 sensors/catalytic converters. The test drive was long enough so that if someone had recently reset the CEL, that the fault would've likely manifested itself again, and triggered the light.

Wayne · Accepted Answer

2003 CLK 430 4.3 litre....

Providing that the vehicle is starting out in 1st gear (not a transmission issue) and providing that there is no trouble codes or a check engine light illuminated and the vehicle has been run on the wrong type of fuel it is entirely possible that ring gear adaptation limit has been met and you are feeling the result of retarded timing.
  Resetting of ring gear adaptation with scan tool is needed to reset engine computer's memory of misfire adaptations. The engine would run good at idle after repair but would develop a misfire at high rpms under load.

Anonymous · Answer

2003 Clk 430

Bandit-05 · Answer

Yes, the engine is designed for and prefers a diet of premium fuel.

As for the hesitation, Acid is correct that stumbling/hesitation on the M112/M113 engines is often caused by either a bad ignition coil or bad suppressors.  Given the mileage, it could be as simple as worn spark plugs if the current ones are original.  This will usually cause the check engine light to illuminate but not always.

Anonymous · Answer

Guesswork is often the most expensive way to solve that kind of issue
Fuel filter, Mass Air Flow sensor, spark plugs and/or wires, catalytic converter,,,,,,,?
Take it to the dealer and have them isolate the issue for you. It'll cost a few bucks, but it's the quickest and best way to find out what's up.

It's most likely to be a bad ignition coil, so a coil and one spark plug are likely to solve your problem. A factory trained technician can quickly figure out which coil is bad.

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Question about a 2003 CLK 430 (C208)?

4 Answers