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Car help!!!

edited November 2009 in Not Sports Related
Is there a mechanic amongst us?

excuse my complete lack of any car know how what so ever.

I have a vauxhall zafira 1.8 (automatic). I'm getting a bit worried. at a stand still if i rev the engine and then take my foot off the pedal the revs drop really low sounding like the engine is about to cut out. all the lights dim and then it revs up on its own a couple of times. it also happens when you drive really slowly. does this sound bad? My kam belt is nearly due btw.

Was hoping someone could give me a little heads up as i have no funds to take it in somewhere but still need to get to work. any advise would be much appreciated.

Comments

  • Im no mechanic I'm afraid but I do know that Vauxhalls are notorious for cam belt problems.
  • edited November 2009
    The fault you describe is not cam belt related. However if the cam belt is at it's 'due for change' mileage, get it changed. Yes it will cost you, but if it snaps whilst you are driving it will cost you much more!
    When i first started driving 35yrs ago!!!! if my car wasn't running right i lifted the bonnet and took a look. Nine times out of ten i could find the problem and rectify it. Things have changed now. The 'modern' car is, largely, not user maintainable. Engine function and control is monitored by an onboard ECU (engine control unit) It relies on dozens of sensors all over the car.
    Assuming the car starts fine from cold (as you don't say) It sounds like you may have a problem with the fuel injection system. The only way to find out is to take it for a diagnostic check. Vauxhall can of course do this, but it's often cheaper with a private garage.
  • Could also be an alternator problem or even the coil. Better off getting a mechanic to take a look. I know a good & cheapish one in Sidcup. Whisper me if you want his number
  • Just spoke to one of our mechanics at work, one of two things is likely, Alternator as Dave Mehmet says, or Engine Management fault, ie, the computer is not doing its jobs properly.
  • Carlsberg, I had a similar problem with my old Vauxhall Tigra about 6/7 years ago now. I was told it was down to the additives in the petrol which clog up the piston chambers in the engine which basically stops the pistons from moving up and down and firing correctly. This was a well known common fault with the Tigra's along with the dodgy cam belts (which I had replaced twice). Vauxhall stripped down the engine, reset the pistons and its been fine since but they advised me to steer clear of Shell and Esso petrol which is full of additives and stick of BP, Texaco and the cheaper supermarket stuff. Dont know if that really makes a difference but have stuck to their advice since.
  • edited November 2009
    Dodgy alternator by the sounds of it - EM systems check will identify it straight away.

    I've had problems with a Vauxhall alternator before - if you have no funds for a diagnostic check, try hitting it with a wooden hammer. Seriously! It may free up any part that's jamming/sticking.
  • Borrow a meter or get a cheapy from a garage to see if the alternator is charging the battery, your average 12v car battery should be charging to around 13.2v and hold that charge!! leave the meter on the battery (obviously stationary) ;) until fault occurs and watch too see if the voltage drops away. Then find the pos and Neg post on the alternator it should be giving the battery a charging voltage! if it isnt the alternator is u/s, if it is the battery is u/s.
    As said above the newer cars are not designed to DIY fault find.
  • similar issues on my merc, turned out to be the "Air Mass sensor" - at £500 -apparently the mass of air changes at different temperatures an dpressures....who'd have thought it
  • The reason i queried 'does the car start fine from cold' was if the alternator is not charging the battery, it won't.
  • thanks for your help. the car starts fine and the bat is fine. i spoke to a guy at work that to my pleasure had a vauxhall mechanic mate. he rang him and explained my problem and the guy reckons it is a dirty throttle body?!?! he said there is no need to worry too much if there is no fault light showing on the dash (which there isn't).
    I have booked it in for a Cam belt next week so i will see. Until then im going to ignore it although it's a bit embarrassing when i start kangaroo jumping at the traffic lights.
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  • Had something similar once, turned out to be a fuel monitoring sensor gone wrong (which tallies with advice above), gave the effect of running with the choke on all the time and running very rich. Doesn't do the 'cat' much good either!
    P.S Who remembers pulling the choke in and out back in the day: knew were you were in those days.
  • Spoke to a tech at our place this morning: odds on it's the 'potentiometer'(?) which is an electrical component attached to the throttle body and which measures and corrects the air/fuel mixture. Being electrical, if it goes wrong it can effect the ignition system etc. Good luck.
  • the guy from vauxhall said if there is no fault light on the dash then it wont be a electrical problem. its getting worse tho. the engine is cutting out now. 4 times on the way home. And anyone who has an automatic will know it can be a nightmare if your engine cuts out in the middle of the road. there's no way of pushing it out the way.

    Its getting seen on Wednesday morning so i hope it will get me to work and back tomorrow.
  • Do all the dash lights come on when you turn the ignition on, especially the engine management one (picture of an engine) ? This should go off after a few seconds without you starting the engine.
  • That sounds to all ends an alternator is dying slowly and painfully.
  • Mate when the engine cuts out what happens to the power stearing and brakes ? these usually help you avoid smashing the f**k into something if they are working !
    Sounds to me that you need to get this car into a garage before you hit something or grid lock the whole of south east london by breaking down.
  • Yes, don't risk the Blackwall Tunnel, you would be popular!
  • sorted! air flow meter. £410 hard earned english pounds (with cam belt) bloody cars!!
  • Unlucky mate, gone are the days when engines were simpler to fiix. You should be OK for a few thousand now though.
  • I see why I'm an Electrical Engineer now and not IC................." Battery or Alternator" ............. shakes head..
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