QuestionQUESTION: since october 09 my car has been problematic over difficult starting,cutting out when doing a low speed at islands,traffic lights and junctions.whilst doing a steady speed eg 40mph the drive is perfect.had new battery fitted, replacement distributor cap, and recently paid a local garage £250.00 to fit a secondhand replacement part think it was fuel related?i have monitored the cars behaviour for 4 months, it seems that when the at mosphere is damp it then becomes difficult to start and cuts out when going into reverse.sometimes it seems to take off almost as is something has released that has been semi functional perhaps fuel related or a wiring problem or dampness. put 97octane in.It will start first time when the weather is freezing although the damp days bother its behavious pattern.
ANSWER: Brenda,
Excess moisture can cause problems with electrical and fuel related issues. Start with the lease expensive and least difficult to accomplish. Raise the hood at night in absolute darkness. Start the vehicle and look for any signs of leaking sparks through the plug wires. Replace the Spark plugs with the mercedes recommended type, if you have not already done so.
The vehicle probably has a cold start injector that is acting up. Drive the vehicle until the fuel tank is on reserve and add Techron black bottle /injector fuel treatment. Fill with an unleaded regular 87 octane fuel. It may take more than one tank to clean the system Add Techron with each tank. Monitor the performance and get back to me.
Let me know what you decide.
Good Luck
Robert
---------- FOLLOW-UP ----------
QUESTION: Hi Robert many thanks for your prompt reply, will do what you have suggested, check in the dark tonight and decide from there.Hope you dont mind me asking but did you mean 87 octane or 78 octane fuel? and can i get that from any petrol station or a perhaps shell etc?not spotted it anywhere before.
AnswerBrenda,
The octane rating for regular grade is what you should be looking for. Your engine is designed for fuel economy and should work well on the low octane fuels. Look for a fuel that advertises cleaning of the injectors etc but in the regular grade. If you engine develops a pinging sound or faint knocking sound during acceleration then move up to the next octane rating until the preignition stops.
The higher the octane the more antiknock compounds are added. Nickel etc. And that is not needed. These compounds slow the ignition process for large high compression engines like the older racing engines and large truck engines.
Your vehicle should operate better using the low octane fuels.
Also, with the new E-fuels that contain alcohol being (anhydrous)they attract moisture, so are more susceptible to holding water an that will contaminate the system.
Let me know if you have other questions.
Good Luck
Robert
