2000 A4 1.8l bucking like mad...new guy needs help

[cyrjm]

Ok, I'm brand spankin' new to this here forum. I'm a truck guy with a girlfriend who owns a 2000 A4 1.8l. I know nothing about this car and what makes it tick but can pull apart my truck no problem so I need your help. It has 60k miles on it, is driven quite conservatively and has always been serviced at an Audi dealership. Over the past 2 months or so I've noticed when driving it that while doing parking manuvers, or simply putting the thing into drive there is this repetitive low sound eminating through the car, it feels like it's lunging back and forth...the rpm jumps up and down about 200-300rpms and then goes away after I accelerate. Often after coming to a stop it does it while idling too. Difficult to describe but quite annoying to say the least. So, finally we took it to a dealer down in Salt Lake City and they said the throttle body needed cleaning (ok, but how this makes the car act like it has stumps me) and that they needed to replace the jet for the brake booster and replace some broken vacuum hoses running off the intake manifold. As a truck guy I can make sense of this...however, the problem got 4 times worse and the check engine light is on for the first time since she bought it. Now when you put it in drive (with the brake pedal depressed) it starts to do the same thing...surge and pulsate with the tach all over the place...but now it gets increasingly more violent...it bucks forward like crazy! I'm convinced that after spending 290 bucks they made the problem worst. We are bringing it back to the dealer this week but I want to be armed with some information so she doesn't get roped for several hundred more dollars. This isn't a knock on you guys because obviously if you're using this wonderful forum you have educated yourselves about your Audis. However, I'm convinced that this dealer generally doesn't deal with many Audi owners that actually take it upon themselves to want to know what's wrong...they will just pay whatever it takes to get it fixed. They assumed this about my girlfriend and I'm not sure that what they supposedly fixed was even related to the actual problem.

So, I need input. Sorry for the long winded post but please, educate me so I have a clue as to what is wrong with this thing. Thanks for your help!

JC
park city, ut

 

[imported_RastaS4]

Is your car a 1.8 Turbo? Well check the Air mass...could be the problem! Check your spark plugs (when did she change them?). Let them put it on a VAGCOM machine and analyse if there are any fault codes. Worst come to worse, take it to another dealer.

Hope it helps

G

 

[cyrjm]

Yeah, it is turbo...now, i'm only familiar with naturally aspirated engines so explain the Air Mass to me?

 

[jonathanA4]

I believe it keeps tabs on the air/fuel mixture.

cyrjm, does this happen all the time? I've heard of this happening at idle when the climate control is on, but what you describe sounds like quite a fluctuation in rpms.
It should be idling around 850-900.

I'd take it in and have them VAG-COM it. I'd ask for the error codes too, if you want to do some research on the problem that will help a lot as well.

 

[Markey]

My car has been doing this, at idle the revs jump up and down and on a couple of time it has actually stalled.

First they said it was the AMM so i had that replaced now they have run some more tests on it and say it is the Oxygen sensor on bank one, somthing along those lines. So i am haveing that replaced and it will hopefully sort out my problems out i will keep you posted.

 

[cyrjm]

jonathanA4...yeah, the first thing that came to mind was the climate control putting a strain on the engine but when turned off...problem doesn't go away. I'll make sure they hook up their diagnostics this time but is there a way to get the error codes myself or does Audi not allow the driver to do that?

 

[jonathanA4]

cyrjm, yeah my climate control does that sometimes after driving hard and then idling, but not violently - just a bit - if I turn it on 'econ' it doesn't do it.

As for the diagnostics, I'm no expert at all, but from what I understand to get the error codes you need a VAG-COM (cable and software) which will spit out the codes onto your computer. But that is basically what the dealer is going to do. I would still ask for the codes just to know what's going on.

 

[imported_RastaS4]

[ QUOTE ]
Markey said:
My car has been doing this, at idle the revs jump up and down and on a couple of time it has actually stalled.

First they said it was the AMM so i had that replaced now they have run some more tests on it and say it is the Oxygen sensor on bank one, somthing along those lines. So i am haveing that replaced and it will hopefully sort out my problems out i will keep you posted.


[/ QUOTE ]

Oxygen sensor might be a problem too...it shouldn't be too expensive as I changed them and the knock sensors just to be on the safe side. I think it would be wiser to check it at any mechanic with a VAG-COM.

G

 

[cyrjm]

going to the dealer tomorrow...we'll see what they say...

 

[dann959]

I have have come to the conclusion that many US audi dealers are nothing but royal pains in the ****. If I were you and this prolem isnt getting sorted out take it to a good local german machanic that is familiar with vw's audi's bmw's and mercedes. These are the guys that know their shi* everytime i have called up an audi dealer and this is many occasions in two different states they tell me I have to wait two weeks for an appointement. A lot of times like you said they will rope you in replace this that and the other thing and slap a $2000 BILL IN YOUR FACE. As far as the UK goes well you chaps seem to have pretty good audi dealer service. God bless you I wish our dealers could take a lesson.

As far as your problem goes check out if the fuel filter has ever been replaced.

 

[Carbono]

i'm affraid, but a broken vacuum hose can cause that problem. and to clean the throttle body will help, too. i assume a lot of carbon built up and the flap doesnt close prober.

i'm not sure, but there was a recall in the states (i believe it was called "KU" recall, related to throttle body and vacuum hoses), your dealer should run a vin check!

cheers

 

[cbass]

Ok, did some more checking on the system too rich code. It looks like that one could also be related to an O2 sensor. It could be related to the MAF or to an intake system leak also, but because you have the other code there, I would bet that getting the O2 problem sorted would fix both codes. Again, if you come down to Orem much, shoot me a line and I'll hook up the vag-com for you and we can log the O2 sensors to monitor their function and see if we can pin down the problem a little more. Good luck with it!