Mercedes: mercedes A 150, mercedes a 150, fuel contamination

Question
QUESTION: Hello,
Hope you can help.
It is my wife's merc a150 recently developed a fault went to the local garage and they said it's a acceleration sensor, but not sure and have to investigate, also said could be injectors.Anu suggestions.
Please help

ANSWER: Zack,
What year model vehicle, how many miles, what are the symptoms of this "fault". When does it come on. Full time? Part time? Hot weather? Cold Weather?
What fuel do you use, reg? Premium? When is the last time the vehicle was services, new plugs, etc. When was the last time fuel treatment was added to the tank?
Rob

---------- FOLLOW-UP ----------

QUESTION: Hi Rob,
The model is 2005 A150 55000km on the clock.Last service was in jan. 09. The symptoms are: in the first day before we took the car in the garage was terrible  rattling and vibrations from the engine it was  like running on one cylinder only really bad.Then we took the car to the garage and they said the above.Yestarday I replaced the spark plugs and discovered they were really burned and old(believe they were never replaced on the last service)and added injector cleaner.The car is slow on take off and less power over all the engine light is on permanently now.

P.S A few days before all the problems the fuel was really really low.

Answer
Zack,
I suspect that your have fuel contamination. Possibly water, and or sludge stirred up from the low fuel condition. The computer is trying to compensate for some issues and powering off the computer may allow it to re set the points. Now, disconnect the battery terminal and wait 30 minutes before reconnecting.
Now that the plugs have been changed, that should help.  I recommend that you change the fuel filter. And check the air filter for dirt.

Pour a bottle of Techtron fuel treatment in the fuel tank. If the skipping and missing will allow, take the vehicle out run it hard on the auto bauhn. The catalytic converter need to get up to temperature to burn off the contamination so the O2 sensor can read properly.

Remember that the computer need to adjust the fuel ratio base on air coming in and fuel/air mixture going out. It also senses air pressure coming in as well as temperature going out.

Have you smell any sulfur odor from the exhaust? A clear indication that the converter is clogged.

If you purchase fuel at the same location, Ask the dealer if they have had any complaints about water in the fuel.
Good Luck
Rob