I've cleaned the throttle botttle- thoroughly cleaned, removed and cleaned also the ICV actualy soaked the inner part with throttle cleaner for 15 mins. and shook it..rinsed it with the cleaner, checked the voltage on it is reading 9V. Changed the spark plugs, replaced the fuel filter, replaced air filter, checked any vacuum leak(three times)--none. As I went with the last 500 miles I've alternately put fuel injector cleaner & complete fuels system cleaner with half full tank on.
As I went on doing these I see improvements on it's idle, to gauge it from 1 to 10, it was3 now I would say around 7. Idling at 800 rpm drops to 500 rpm (that's after at idle for 4 mins.-I timed it), then steady at 500 rpm goes up to 800 rpm. I'm thinking of checking the spark plug wires, ignition coils, I don't havereceipts or service records from the previous owner that these were replaced. It has 93,000 miles on, 1996 A4. It runs good, good power on high and low ends. Idle doesn't affect engines performance, very smooth rpmstanding rev from 1,000 rpm to 6,000 rpmno misfiring or rough spot,so I'm scoping it to just idle issues.
How do I check the coils and the wires? Other than thoseare there any parts I should look into? Appreciate any inputs. Thanks in advance!

 

MAF sensor. Could be dirty. Clean it with electronic cleaner. See if it idles better. My second guest is the coil pack. They are so famous for causing so many issues even with rough idle and no misfirer. Third guest; you have a v6, possible EGR valve causing a bad build up to your manifold. Hope that is not the case but very likely cause for bad idle. I use to own a V6 12v. That was my issue and even after they clean my manifold. Still idle rough after 10-15k miles. If you plan on keeping the vehicle, do your timing belt if it hasn't been done. Any codes?

 

EJ30 forgot to mentioned earlier that I did cleaned the MAF sensor when I did the throttle, it's actually new when I got the car but cleaned it still nevertheless. How do I test the coil packs? I'm not really certain on how to test them. The EGR haven't looked into, search the forum for the DIY of cleaning the EGR found some threads but if anybody has specific how to instructions for the V6 I would greatly appreciate it. Im sure I can figure it out with guide from other engine models, butjust to eliminate error for first timers. For clarification..do I have to buy gaskets for the EGR when I do this? If yes w/cone exactly? The timing belt that I need to change for a clean slate maintenance as I take over the car. I don't have any codes on it.

 

Have you pulled any of the injectors to see if they are spraying properly?

 

I don't think there is a way to test coil pack with an ohmmeter. If the vehicle is misfiring, you can use a vag-com to check for bad coil packs by swapping the coils and see if the misfire follows. You probably won't find much info in the forum here about V6 EGR valve since most audi owners here have turbo. It's not the valve that needs replacement but the built up of deposit it leaves on the manifold. The cleaning of the manifold can get expensive and the bad part is it won't fully resolve your problem of rough idle. The deposit comes from using cheap gas with low octane. I had taken mine to the dealership and had them clean it and it still ran rough to the point were it dies at stop light. If you don't have codes yet, it could mean the problem hasn't gotten really bad to leave a code. Here is a website you can hit if you haven't already. http://www.audidiy.com/home.html. I didn't understand your statement. Did you have the timing belt, water pump and thermostat change? If not, that is one big project that needs done.

 

NEW2ME I actually pulled 2 injectors only and they are spraying properly. Over the weekend I did a compresion test on it just to make sure it's not a compression, block or head issue, the results were ok on all 6 cylinders.
EJ30, thanks for the link really been lookingfor such DIY links for the Audi it's a big help. Yeah on the EGR really didn't have anu luck on finding specfic topics for the EGR. I'm putting 91 gas on it right now just to check and lessen the systems build up right now, obviously the previous owner was using cheap gas. It's not misfiring actually just rough on the idle, what I did while the engine is idling I pulled 1 by 1at a time and put back eachwires from the coil, and totaly bags down almost stalling just doing a simple test, with that somehow conclusive of the coils are fine right? The Timing belt, water pump and thermostat those I haven't done yet, I don't have that much confidence on doing that myself I'd probably bring it to a Indy.

 

timing belt, water pump, and thermostat are not hard to change out, it just takes a little work to remove the stuff around them to get to them (mainly the water pump & thermostat). it seems daunting but it really isn't, I would suggest that you just do it yourself. When we did we took off the radiators entirely to allow better access to the engine. I would suggest using plastic bags with a sharpie to put all the bolts in so you know where they all go.
When we put my car back together (1.8T 2000 B5), it idled pretty rough for a bit then smoothed out and hasn't been a problem since.

 

ORANGE thanks for the encouragement, I'd really would like to do it but I worry a lot interms of the timing mark. Figured it out the belt is much easier to fix than the chain but I'm really anxious of making a mistake on the mark. Do you happen or anyone to have a DIY link on how to do it on a 2.8? EJ30 had sent me a very helpful link on the DIY's but nothing specifically for the 2.8, pretty much the concept is the same I'm sure just making certain and eliminating guess on it.

 

It should cost around $650 for a local shop to change out the timing belt, water pump and thermostat. Make sure that they replace all outer belts while they are doing the timing belt. I wouldn't bother to DIY cause you will need to buy special tools and to make it a whole lot easy, complete removal of front bumper. I would pay the cost since it should come with a small warranty as well. Don't take it to a dealership cause they will charge 3 times the price of local shop.

 

a few things to look at

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