I am interested in buying a car from a friend of a friend, they said it goes perfectly except the revs drop causing the car to cut out when you stop. What are the causes of this and underlying factors as I do not want to buy another debt. Any help would be appreciated.

  • 2
    Make, model, year and mileage? We need to know if fuel injected or carbureted and age of system to determine what could be causing this condition.
    – zipzit
    May 21 '17 at 3:29
  • The basic problem is probably that the idle is too low, so increasing it should help, however you'll need to provide the info zipzit asked for.
    – Rory Alsop
    May 21 '17 at 10:00
  • manual or automatic?
    – Aus
    May 21 '17 at 19:48
  • Don't by the car.
    – JimmyB
    May 22 '17 at 12:10
  • Mitsubishi, Legnum, 1997, 196000kms, Tiptronic, Fuel Injected.. Cheers unsure age of system sorry..
    – Billy King
    May 23 '17 at 7:49

In a car of this vintage there should be an idle air control valve. Especially if the car has been sitting for a while this valve could be sticky caused by buildup of oil or fuel vapors. It could possibly be removed and cleaned with carb cleaner or similar product.

Reading material about mitsubishi galant IAC valves

  • Thank u very much I will check these out and let u know how I get on... Appreciated
    – Billy King
    May 25 '17 at 18:47

A possibility is a vacuum leak somewhere. While running at high RPMs, a small leakage of air is not a problem, but when your RPMs drop, a small amount of air leans out the mix too much. The old way this was checked was to check all vacuum hoses for deterioration or looseness at the ends and if nothing is easily seen, try running at idle and spray the hoses one by one. You can use propane (potentially explosive) or carb spray, some use smoke. Your choice. Google the different methods and see what would be easiest for you. The basic idea for propane and carb spray is that when you hit the leaky hose, the idle will jump up as you are adding more burnable materials into the airstream.

  • Thanx mate I will get into looking at those hoses asap.. Appreciate the help.. Thank u
    – Billy King
    May 25 '17 at 18:49

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