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  • Idle problems.

    Hi folks.

    I just want a bit of advice on how to get my damn car running smoothly again.

    First off I'll let you know that its a 4 cyclinder 8v engine (I know....its not worthy of the forums, but my future intentions are ).

    Recently the car has been extremely lumpy on tick over, some days it is much worse than others depending upon how long it has been left on the roadside waiting for me to use it, generally the longer it is left, the better it is until I have warmed it up and start using it more frequently again. The lumpyness is almost like a very fast but very faint shake, almost like a really fast miss on one cylinder.

    Firstly I thought it could have been a slight blow on the gasket, but after having a compression test on the engine, the car seemed to come up fine. We did notice that one of the engine mounts had broken and another had come loose, so I had the 2 front engine mounts replaced hoping the judder I sometimes get when I pull away would be fixed....well it has improved but is still not great.

    I have been told that a lambda probe can truely transform a car, well, being a 1990 8v I dont beleive this car actually has one, so unfortunatly that seems out the question. Next on my list was the mass flow air meter but this car actually uses a jetronic style fuel injection system developed by bosch, having checked it we found the engine was running lean, but apparently that is normal for this type of injection system and car.

    The audi specialist we take it to is a great beleiver of actually repairing as apposed to spending a great deal of my money buying new parts, he doesnt like to give people huge bills and will do all he can to avoid major work unless of course he has to, and seems sheepish passing a highish bill across. He is a great guy and obviously knows what he is doing but his method of thinking is that so long as I have this rough idle and its not doing any damage, then theres no reason to worry about it, but tbh, I hate the idle, it irritates me everyday I drive it and Im not sure what is causing it...I think its the fuel injection system.

    Oh and one other thing, if the car is cold it starts up very well because the mixture is lean, and if the car is warm it is also fine, but somedays I start the car up and it wants to stall and just manages to remain running or it does stall. If I try and start up straight after it has no problems starting but then starts idling badly.

    I have been told these are characteristics of this engine and with age and high mileage this happens. Apparently I could be spending far more money than I would want to on old technology and instead should just be content with how its running now.

    I know its a long post, and may not make a great deal of sense, But I am truely mystified.

    Any help guys?

    Rob

  • #2
    You tried cleaning the ISV?? (idle stabilisation valve)
    Try removing it and cleaning with carb cleaner, then spray a little WD40 in.
    I'm not up on the 4 cyl engines as I've only ever had the I5 lumps, but this question often comes up over on audifans.net for the 2.0 8v, and this seems to be the first port of call.
    Oh, though I'm not 100% sure, I seem to remember that the 2.0 8v does indeed have a lamda, though no-one me if I'm incorrect.
    I've attached a pic below of where the ISV is on the 2.0 8v.


    Failing that, it could either be a blocked crankcase breather, or a split breather pipe somewhere, again, I've just dug these up from audifans.

    HTH
    2001 Avus Silver B5 RS4.
    2004 A4 Avant 1.8T quattro Sport-LE.
    1995 S2 Coupe - sold (sniff)

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    • #3
      No flaming required fourrings. Thanks very much for the help, Im gonna try anything, im just sick and tired of the idle problems.

      I think il lurk around the audifans forum and find out what guys with the same lump have to say.

      Once again, thank you, I'll let you know if I solve the problem.

      Rob

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      • #4
        Rob. I had a "similar" problem on my old 90Q (i5 NG engine). Have you checked the throttle switch ? I had a faulty switch which read anything up to 1400 ohms at full close when it should have read zero. ( Check the specs in your Haynes manual ). It took several hours to replace as the switch was buried under the intake manifold. Completely cured my cars problem. Other things to check - warm up regulator, earth straps to engine, basic mixture setting, air leaks - ( inc dipstick and oil filler cap ), HT circuit and plugs. If you need the manual or digi meter PM me. Good luck James.

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        • #5
          Does It Have A Maf? If So You Might Have Split In The Pipe After Alowing Un-metered Air To Be Sucked In

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          • #6
            Still need to get to the bottom of this. Only just realised you guys had replied in the thread, sorry!

            Im not sure if it has a MAF, il check it out.

            And James, I may well take you up on that offer in the new year, got a busy schedule ahead of me before then im afriad

            Thanks chaps!

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            • #7
              snap! i ve a 1.8 gt coupe doing the same thing. i ve changed all elecs etc too.
              runs fine until warm then idles at 1000rpm, try to rev and it cuts out. will post when its done
              also have an aby to go into my coupe quattro but am missing a MAF. anyone got a spare 4 sale?

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              • #8
                Righty then, so far I have found nothing wrong with the car, and I have reached the end of my tether.

                If anybody could tell me where any audi specialists operate in the west london area / heathrow area I would be very grateful, if not I think i'll petrol bomb the bloody car!!

                I Just dont have the time to keep trying to chase this problem as I'm always at work.

                Any help is much apreciated.

                Rob

                Comment


                • #9
                  Hi Rob,

                  I had a similar car with exactly the same problem a couple of years ago. My problem was the idle switch. When I was releasing the throtle, the switch wasn't quite getting reached. I went through all the same things as everyone has suggested like cleaning the ISV etc. I actually got a new one (well a second hand one).
                  One thing to try, when the engine is idleing roughly, open the bonnet and try forcing the throtle body cam round into it's rest/idle position and see if it make a difference. If it doesn't, try doing the same with the engine off and see if you can hear a microswitch click when the throtle is in it's rest position. My throtle was a tiny bit sticky right at the end of it's travel wich caused this problem. Once I found the cause, I totally stripped the throtle body and cleaned and lubed all the moving parts.

                  Hope this has been some help.

                  Tony.
                  1994 S2 Avant Red. Home Fry. 100k.

                  Comment


                  • #10
                    Thanx Tony.

                    Well when I get the chance to take a good look at the car in the light, I will definatly have a good ganda's.

                    It will be a relief when I get this damn problem sorted!!

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