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  1. #1
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    Audi 90 quattro intermttant lack of power, back fire in injectors

    Hello to all. Please help if you can. After I start my car and run it on the road for a few mins, I think round about the time that the automatic choke closes, My car has big loss of power and a farting popping noise comes from the injector or around there when I put my foot down, but the car does not rev up. If I leave my foot on the accelerator it does rev up eventually but a max of 4000. Some times this clears with a lot of reving but I have noticed that: If I leave it chugging away in this state until the temperature rises to 90 then above 90 when the cooling fan comes on I can here another wee click like a small electric switch opening or closing and all of a sudden the car runs correctly and will continue to do so even on long journeys until the next day when I switch it on again where I have to go through the whole routine again.Anybody know? [img]/ubbthreads/images/graemlins/confused.gif[/img]

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  3. #2
    Rev-head's Avatar
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    Re: Audi 90 quattro intermttant lack of power, back fire in injectors

    What size of engine is in your 90Q

    Sounds like a MAF problem

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    Re: Audi 90 quattro intermttant lack of power, back fire in injectors

    2.3 litre, jetronic11or 111 ke I think.The car is 1990 registered. Seeing as it begins to work with some electrical 'click' noise after it reaches a certain temperature to turn on the cooling fan etc then well I thought it might be a fuel pump relay sort of trouble, reading another post that is here? But who knows. What do you think? It has been fully tuned and I mean fully tuned. and I was told that it had a new fuel pump on it before I bought it. Can try a fuel filter but I am sure it is a fidgity problem (temperamental) that is not mechanical, as it sorts its self out occasionally, if you know what I mean? Can you help!? It is a lovely car that I do not want to give up on.

    Nially

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    Re: Audi 90 quattro intermttant lack of power, back fire in injectors

    Does the car emmit any smoke from the exhaust when this problem happens?

    Is the engine an AAR code 5 cylinder by any chance? :-)

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    Re: Audi 90 quattro intermttant lack of power, back fire in injectors

    Hi. No it has no smoke just a week smell of petrol. It is a 5 cylinder but it is an NE or NK code engine cannot remember exactly just has an N in it.

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    Re: Audi 90 quattro intermttant lack of power, back fire in injectors

    I think your model has a warm up regulator bolted to the engine block on the right hand side of the engine (if looking from the front), there are two pipes going to it and maybe an electrical connector?

    During the warm up phase this regulator/controller should change the pressure in the fuel system allowing more fuel/air to enter the engine to overcome the drag/resistance of cold components.
    If this is faulty then the engine can be overfuelled causing the engine to flood. Of course the opposite is also true in which case fuel starvation is the result.

    Your fuel system is likely to the either the KE-Jetronic or the KEIII-Jetronic. The KEIII does not have the mechanical warm up regulator but rather uses a lot more electrical sensors to control everything.

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    Re: Audi 90 quattro intermttant lack of power, back fire in injectors

    Hi. I will check out what you are saying thoroughly, as this is a trial and error stop. I do have a KE111 jetronic system I have checked, you are right. That is a new one I must admitt, but worth looking into. Do you not think that it might be the fuel pump relay switch, at all? Just a suspition of mine. cheers for now. will let you know, and please let me know your thoughts on this.
    Nially

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    Re: Audi 90 quattro intermttant lack of power, back fire in injectors

    The fuel pump relay is a multiple contact switch that supplies power to both the fuel pump and to parts of the ignition and ECU's, this relay is either on or off depending on the state of the engine. So it is unlikely that this switch would activate only at 90C, in fact if that was happening the car should not run in the first place as the engine would not get fuel. However having said that it may be that the other contacts in that switch that supply power are dirty??? (it supplies directly to the low tension side of the coil, the cold start valve, the ISV, the carbon filter valve, and the oxygen sensor heater)

    Your system will have two ECU's, one to control the fuel side and the other to control the ignition side. These ECU's receive signals from a whole host of sensors (the KEIII system was the last of the Jetronic systems used by Audi and has the most electronics). Those sensors named above get their power from the fuel pump relay.

    The thing with this issue is that the problem is clearly temperature related. Hence I would tend to look first at all the components that relate to temperature. Secondly those components that operate due to temperature change, like the cold start valve. It sounds to me as if the engine is being either over or under fuelled

    Perhaps the best at the moment is to take the car to a garage who has diagnosis equipment. They can then tell you if one of the components is faulty. It is quite likely that info about this fault will appear in the log.

  10. #9
    imported_muscle750
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    Re: Audi 90 quattro intermttant lack of power, back fire in injectors

    hi
    I used to have a 100 with similar probs the car never started right from the word go numerous people looked and played including 3 separate Audi dealers and one even called in the main techs from the factory when the car was new and the answer
    "acceptable" basically complete crap, which points to a design fault,
    All the fuel pressures where checked etc, sounds to me as if its running weak when cold , mine ran better when parked on a hill facing down hill and thats no joke either.
    Mine when really bad after it sotrted itself gave it a blast down the motorway at 120mph and it was better for a few days, mine was the 5cyl RT. basically check for fuel smell on starting mine did flooded itself like the titanic. put 60000 miles on it in five years and the only time it died was when the radiator exploded!!!
    Unlucky!!!!!!!!

 

 

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