Guess the fault...

Discussion in 'Cars, Bikes 'n AFVs' started by Grey_Mafia65, Mar 7, 2013.

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  1. Proton Savvy 1.1 petrol engine

    ok, stop laughing

    After driving around 15-20 miles, when either slowing down to stop or turn or idling whilst at traffic lights/junctions, it will just cut out. Engine will turn over but not catch. Doesn't happen every journey, 1-2 times a week. What seems to get it going again is spraying WD40 or Easy Start into the air inlet pipe, it won't fire up straight away but after a few go's.

    Just got back from the garage, having left the mechanic scratching his head. He's looked at everything he can, leads, sparks are fine as is fuel filter. He couldn't replicate fault so diagnostics just showed everything running fine.

    It's going back in again when he and I have the time for him to take it on a long run to try and replicate the fault, but if anyone's got any ideas (apart from burning the car out), I'd be grateful to hear them!
  2. Have you got fuel in it? :D

    Sent from my HTC Desire using ARRSE mobile app
  3. Air leak in the induction system
    Allows un-metered air into the intake and the engine runs too lean and cuts out. Easystart/WD40 boosts the fuel air mixture enough to restart

    Not familiar with Proton engines but the problem used to be common enough on V12 Jaguars and Range Rover V8's
    Can take bit of tracking down. Had it on a Jaguar once and after days of head scratching I happened to lean on one of the intake manifolds and the problem disappeared. Turned out to be very slightly loose manifold bolts.

    Just an internet guess though
  4. I'd say a blocked fuel tank breather is a possibility if it's only happening on longer trips when enough of a vacuum is created to cause fuel starvation.
  5. Sounds like a typical woman driver.

    My solution, get a man to drive it. I am available.
  6. Thats a renault engine isnt it? if so it Could be the TDC(top dead centre) sensor.
    Cheap an easy fix if it is, get you're mechanic to check that. It's not something they would commonly do for a fault like that.
  7. Grumblegrunt

    Grumblegrunt LE Book Reviewer

    if it was a bike I'd say a tight valve, weak mix, idle too low.

    adjusting the throttle stop might help it by stopping the slow idle. dont know if the engine has a lambda sensor to regulate the fuel mix as they can get messed up.
  8. Fuel return pipe may be blocked
  9. omm foo foo valve is shorting out to the differential sprocket convertor piston grommet
    • Like Like x 1
  10. Nice try, I know enough about engines not to fall for that one!

    Keep the thoughts coming, I'll be printing them off to give the mechanic ideas (and a laugh).
  11. \Has an engine management light come on? Could be one of the myriad engine sensors that seem so fashionable these days!
  12. I had something similar with a 1.0 Corsa (son's, honest), random stopping, usually during 60mph+ motorway driving. It would eventually fire up again, for no obvious reason, after 5 or 10 minutes. I thought as guzzijon; briefly opening the fuel filler cap once stopped seemed to speed the restart. Fuel starvation seemed a likely culprit. Fuel filter changed, no fault lights, no error codes on the diagnostic gizmo.

    Consulting Mr Haynes, I found modern cars don't have a fuel tank breather; the emission laws require a breather hose from the tank which connects to the inlet manifold, via a carbon filter and a solenoid valve so petrol vapour is sucked into the engine. The solenoid valve is opened as needed by the ECU (engine control unit, electronic gizmo).

    Removing the solenoid valve, I tapped it on a flat surface and a load of carbon granules fell out, all about the size of pinheads. The mesh on the carbon filter had failed and the carbon had been sucked into the valve. The solenoid valve couldn't close, since it was full of carbon. Driving at high speed caused the inlet manifold suction to pull a partial vacuum in the fuel tank, which starved the engine of petrol until it died. Once stopped, air gradually leaked into the tank and the petrol supply was restored. Some cranking was then required to get air out of the fuel lines and the engine started again.

    I wedged a suitable bolt up the breather hose and it stopped happening. I'd bought the Corsa cheap because it kept stopping and varous garages couldn't fix it. It's lasted 6 years or so.

  13. If this going to the mechanic,
    then I strongly advise changing the flux capacitor while he's in there.. Just to be sure.
  14. TheIronDuke

    TheIronDuke LE Book Reviewer

    Good. Tell him he is a disgrace to the name of "mechanic". At best he is a fitter. Tell him you are my close personal friend and I know where his Mum walks her dog. Tell him he has got dreamy eyes but he has until Monday to ******* sort it.

    And get a haircut tell him.
    • Like Like x 1
  15. Don't do that, if it has a flux capacitor you will be able to get it changed last month.
    • Like Like x 1