Question about 1998 Audi A4

12 Answers

Starting after not using for few hours


2.6 a4 avant i have changed idle compansator and have new battery when car is in use it starts first time but when i leave it overnight it is reluctant to start plugs new temperature sender ok if i flick key on off it fires but is reluctant to be rev ved it splutters once it is going the car runs like a dream .butterflyes been cleaned as well














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  • 16 more comments 
  • d6rog Oct 31, 2008

    car is r registration starter and alternator ok no faults showing on e c u either

  • d6rog Oct 31, 2008

    i have put injector cleaner in tank.could it be a fault with new idle comp valve ive replaced.from cold if i turn key for 10 sec and keep doing this i get more response than if i just turn engine over for longer. once started car doesn't want to respond until after about 30 seconds.its like older cars when it needs more choke

  • d6rog Nov 03, 2008

    when i start the auto choke is not on

  • d6rog Nov 03, 2008

    where is the idle air control motor located

  • d6rog Nov 03, 2008

    i use semi synthetic oil. battery is brand new and turns engine over easily

  • d6rog Nov 03, 2008

    i have no loss of power. in fact the car when warm runs better than it did before since all the things i have done

  • d6rog Nov 03, 2008

    starter & alternator ok car is r registration

  • d6rog Nov 05, 2008

    cat converter ok

  • d6rog Nov 05, 2008

    cat. convert ok

  • d6rog Nov 05, 2008

    i understand what your saying about check valve but the automatic choke is not on when it finally starts

  • d6rog Nov 06, 2008

    i put injector cleaner in last week tank is now nearly empty it went in full tank when car is warm runs perfect

  • d6rog Nov 06, 2008

    no have you read all previous comments

  • d6rog Nov 07, 2008

    i have noticed the temp gauge on dash is showing slightly higher than normal

  • d6rog Nov 07, 2008

    i have noticed the temp gauge in dash is slightly higher than before this problem????

  • d6rog Nov 10, 2008

    how can it be that, if after starting it runs fine. and if left for an hour or two it starts 1st time i seem to think it could be a faulty temp sender . i changed it this afternoon i will let you know in the morning after starting.

  • d6rog Nov 10, 2008

    you obviosly havent read previous comments

  • d6rog Nov 11, 2008

    thankyou for all possible solutions to my problem, the car is ok now the problem was faulty (new) temp sender reading too high , telling the computer it didnt need choke.





    ROGER REEVES

  • d6rog Nov 11, 2008

    SINCE I CHANGED TEMP SENDER THE CAR IS OK.



    THANKS FOR YOUR POSSIBLE SOLUTIONS.



    ROGER. OVER AND OUT.

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12 Answers

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I gotta go with emmissionwiz on this one. Your check valve in fuel pump is not holding causing fuel to drain back this is why when you cycle key you are running pump everytime building pressure. install a fuel pressur gauge and you will see the pressure bleed off after a while. replace the pump and will solve problem

Posted on Nov 07, 2008

  • TripleTauto
    TripleTauto Nov 10, 2008

    it takes a while to drain back like sitting overnight. your complaint points to this as cycling the key runs the pump and builds pressure up

  • TripleTauto
    TripleTauto Nov 10, 2008

    i have put injector cleaner in tank.could it be a fault with new idle comp valve ive replaced.from cold if i turn key for 10 sec and keep doing this i get more response than if i just turn engine over for longer. once started car doesn't want to respond until after about 30 seconds.its like older cars when it needs more choke



    I have read all posts. The fact you have to cycle key is either to get fuel up to injectors or to make injectors spray extra fuel into cylinders. If you are holding fuel pressure,Only way to know this is to install a gauge,Then the reason for this is to get the extra fuel. Need to be able to hook a scanner to vehicle and see if it is reading proper temps and data to diagnose.

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  • Audi Master
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It is clearly a problem with air-fuel mixture not getting enough amount of air, as you told us, it is like there is not enough choke.
Naturally here things are more complicate than on an old carb car, and the problem can be caused by more than one part.

The ECM is the main car control module (the computer, a code reading on the car computer can return a list of error codes that can help troubleshooting the problem.

Check the Air Filter and the air intake, eventually try to remove temporarily the filter. If the care idle normally without the air filter, then replace the filter. You can also replace the air intake with a bigger one (monster air intakes).

The Air Mass Meter and Mass airflow sensor measure the mass of the air getting into the engine. If there is a problem with this parts, you may experience idling problems

The Oxygen Sensor is used to determine how well the fuel is burnt though the engine combustion operations. Then the electronic fuel system adjust mixture to save fuel. When oxigen sensor is bad you can get a low idle. Here you get a replacement.

If you decide to do it yourself I suggest also buying the Repair Manual , if you haven't done it already.

And do a computer scan as first thing.


Posted on Nov 06, 2008

  • Ginko
    Ginko Nov 11, 2008

    Nice to know.

    Often, the most stupid faults are the most difficult to find, like in this case.

    Goodbye.


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It could mean a partially clogged catylitic converter

Posted on Nov 03, 2008

  • Ronnie Houston Nov 11, 2008

    you said you cleaned the butterfly on the carb,,,,you may have sprayed too much cleaner in the carb partially clogging it and making it stick.

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You may need to get a new fuel pump, fuel filter, starter, or alternator. Try going to a mechanic and see what they say and they should be able to diagnose and fix the problem for you. But it seems as though it may be more than one thing because a faulty alternator will drain a battery and make it start sluggishly, and the fuel pump may not be giving gas fast enough probably because of a clogged fuel filter. So just get it checked at a shop and they should fix it.

Posted on Nov 03, 2008

  • 1 more comment 
  • Jazz Boyce
    Jazz Boyce Nov 03, 2008

    You may also have to get most your fluids flushed since you say you have had it sitting for a while. Some fluids settle and separate causing filters to get clogged and the engine to not start at first.

  • Jazz Boyce
    Jazz Boyce Nov 03, 2008

    Well since the alternator and starter are good, try getting the fluids, fuel pump, and the fuel filter checked by a mechanic and see if either one is the problem.

  • Jazz Boyce
    Jazz Boyce Nov 05, 2008

    When you take it to the shop, they should connect your car's computer to their computer and should be able to see a code that should tell them what the problem is and how much it will cost to fix.

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I greatly recommend that you should also check the Fuel strainer. it could have been blocked. blocked strainers causes hard starting and low engine power or even sudden engine stop.
if your cars was stock for months or even weeks, try to clean also the sparkplug connectors.
check also your car's engine oil, it should not be too thick as this would not circulate properly (thick oil gets even thicker at cold temperature). you could use thin synthetic oil.
starting after not using for few hours - 960f33c.jpg

strainer
e41d1d1.jpg

Posted on Nov 03, 2008

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 It sounds like your choke may be hanging up.  A choke releases two ways, as the engine gets warm.  One way is by a small electric heater in the choke housing.    Another way is that it pulls warm air off the exhaust manifold.  Verify that the choke releases as the engine warms up.

Posted on Nov 03, 2008

  • AbdulRahiman S Nov 03, 2008

     Check the choke linkage, it may be hanging up.


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Sir,
Cold engines might experience problems at the time to start due to different reasons. One of these reasons can be based on the effect which cold has on liquids evaporation. When it is cold, gasoline evaporates less and this cause it to be more difficult to burn due to the fact that it is burnt when it is evaporated.
Another reason by which a cold engine might have problems to start is caused by the fact that oil becomes much thicker in cold than the way it is in hot. Oil, like any other liquid changes its consistency when it is exposed to very low temperatures as well as it changes back when it is in a very hot weather, and this might cause oil to have problems at the time of circulating in the car engine.
Besides the engine, car batteries might experience problems while being in cold weathers as well and this could affect the engine. Batteries function through chemical reactions which loose agility while being cold and therefore, in such circumstances, batteries don't function properly. When this happens, the car energy becomes affected and this causes problems for the engine start.
If these three problems happen together, starting an engine might become a really hard task to achieve. In order to overcome the lack of gasoline evaporation problem, you can spray ether into the engine which would evaporate quickly and help the engine start. Besides this, you can also to prevent having oil too thick which wouldn't circulate properly by using thin synthetic oils. You should also try to maintain the car isolated from cold as much as possible, but by using the two last mentioned methods you would experience much less problems at the time of staring the car in cold weather.

thanks
good luck

Posted on Oct 31, 2008

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This sounds like the throttle position sensor(TPS) , to test , leave key in forward position, then under the hood unplug the sensor then plug back in , if it starts right up then you need to replace the sensor , could also be idle air control motor(IAC motor) do the same to check it

Posted on Oct 31, 2008

  • 4 more comments 
  • jason Nov 05, 2008

    if you put injection cleaner in the tank then it will act up for a while untill it runs out , unless you put it in with less than a full tank , like just a quarter tank , then you could have ruined injectors

    also this might happen if an injector seal is letting in air, when it needs more fuel to warm up

    did you just put in the injector fuel?

  • jason Nov 06, 2008

    did the problem of start up , start happening a day or so after you put in the injector cleaner?

  • jason Nov 06, 2008

    well I don't think you have a fuel problem since it eventualy runs fine after warm up , so you are getting to much air at start up , you can also try cleaning the IAT sensor and the maf sensor which can cause these symtoms , so try cleaning those sensors and see if that helps the start up problem

  • jason Nov 06, 2008

    also you should refuel be fore you clean them

  • jason Nov 06, 2008

    the MAF sensor is important in that it maintains the air fuel mixture ,so if it is dirty or faulty at cold temperature then that could be the exact problem , and it will need to be changed ,but see if cleaning it makes a difference , also a routine cleaning will give you the best possible performance





  • jason Nov 12, 2008

    glad you got it fixed

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Stalling: Sensors such as the cam and crank sensors signals if the computer don't see it-it will not fire the coil and provide injector pulses. And Idle Air Control Valve not targetting the idle speed and an EGR valve that's cracked open will lean out the air/fuel mix causing it to stall to include the MAF sensor.

Refusing to start at times could be the coolant temperature sensor is out of range and computer not adjusting fuel as needed during initial cold starts.

Fuel Injection Stalling Problems

On fuel injected engines, stalling can be caused by anything that upsets the air/fuel mixture. This includes vacuum leaks or unmetered air entering the intake manifold downstream of the airflow sensor, a faulty throttle position, MAP or oxygen sensor, dirty fuel injectors, or low fuel pressure to the injectors (weak fuel pump, faulty fuel pressure regulator or restricted fuel filter). Like older carbureted engines, a defective thermostat may be preventing the engine from warming up quickly or reaching normal operating temperature. Or, a defective coolant sensor may be telling the PCM the engine is colder (or warmer) than it really is. Any of these conditions can upset the fuel calibration of the engine and cause a problem.

Idle Speed Control Circuit

One of the most common causes of stalling on fuel injected engines is the idle air control (IAC) solenoid or idle speed control (ISC) motor. If the idle speed control device fails to provide the correct idle speed, the engine may die when you slow down or come to a stop. In many cases, the idle control solenoid or motor is gummed up with carbon and fuel varnish deposits. Cleaning the idle port in the throttle body, and the IAC or ISC valve with aerosol throttle cleaner can often solve the stalling problem. If the situation is not improved after cleaning, however, the IAC solenoid or ISC motor may have to be replaced. Check the connector to the device to make sure the connector is not loose or corroded.

Engine Control Issues

Sometimes stalling is the fault of the Powertrain Control Module (PCM) or the inputs to the PCM. The factory programming may not provide enough idle speed when the A/C is on, when the alternator is under high load or when the temperature is unusually hot or cold. The fix here may be to reflash the PCM with the latest OEM update.

A faulty MAP sensor can sometimes mislead the PCM into thinking the engine is under a greater or lesser load than it actually is. The MAP sensor senses intake vacuum, which the PCM uses to estimate load so it can adjust the air/fuel mixture accordingly. If the MAP sensor isn't reading right, the PCM will receive bad information and possibly add or subtract more fuel than it should causing the engine to stall.

The same thing can happen if the throttle position sensor on a speed/density EFI system (no airflow sensor) is out of calibration or had a dead spot. The PCM may not realize the throttle is at idle, and may give the engine too much or not enough fuel causing it to stall.

When attempting to diagnose an intermittent stalling problem, therefore, it's important to always use a scan tool to first check for any trouble codes that might shed light on the condition, and secondly, to look at all the essential sensor inputs to see if they are within range and are supplying accurate information to the PCM.

Intermittent stalls that seem to happen at random are often ignition-related. A sudden loss of spark will kill the engine cold and prevent it from restarting. The most common causes for loss of spark include hot shorts/opens in ignition coils, ignition modules and crankshaft position sensors. Loose or corroded wiring connectors that cause a sudden loss of voltage in the ignition circuit will also stop an engine dead in its tracks

Posted on Oct 31, 2008

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You may want to try a can/bottle of injector cleaner in the fuel tank.Do you live in a high humidity area as moisture can cause this until the engine heat heats it off.

Posted on Oct 31, 2008

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Hi!!!

how old is your car?

try to check the starter!!!
and then the alternator

Posted on Oct 31, 2008

  • ronald suboc
    ronald suboc Oct 31, 2008

    try to check the line that supply in the injection pump

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  • Audi Master
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This problem is caused by the failure of the check valve in the fuel pump, after the car sets the fuel drains back to the tank and it will take repeated tries to fill the lines and fuel rail at the engine to supply the injectors, the sputtering is caused by the air in the line, like a garden hose when it is first turned on, once the air bleeds out of the lines the engine smooths out, have seen this same issue dozens of times in my 20 years as a new car dealership technician, all I did was these kinds of problems, my specialty was automotive electronics.

Posted on Nov 05, 2008

  • 2 more comments 
  • yadayada
    yadayada Nov 06, 2008

    I will bet my bottom dollar the fuel pump check valve is the answer, 30 years as a dealer tech tells me I am right.

  • yadayada
    yadayada Nov 07, 2008

    This car doesn't have a choke, it just adds more fuel when cold, the PCM (powertrain control module) does this based on the temp of the engine as reported by the ECT (engine coolant temp sensor) sensor, Y are you so reluctant to accept the fact that the fuel pump is most likely the issue, is there some symptom you are not giving us, is there black smoke when it finally starts, I am a little confused what you are really saying, and I have been doing this 30 years. Do you understand how a modern electronic fuel management system works? this car does not have a carburetor, no choke, therefore the hard start is due to either a fuel pressure problem or less likely low engine compression or a defective signal from the ECT sensor.

  • yadayada
    yadayada Nov 10, 2008

    I would get this to an Audi dealer, you are not going to get it fixed over this keyboard, I don't think you even try the solutions, just reject them, what is it you would like to hear as a viable repair suggestion?

  • yadayada
    yadayada Nov 11, 2008

    All these guys tried to help, why not rate the solutions that way, your ratings are a bit insulting.

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