Sudden Failure

[newsh]

Suddenly my AAN engine has no power and can hardly move the car. Took my 1995 S6 on a 360 mile road trip last week. Performed flawlessly. Was a real pleasure driving. Noticed that the plastic bottom shield had dropped real low and was clearing the ground by something like 1-1/2". Dropped it off at the shop the next day after the trip to reattach the shield. I get a call from the shop 1/2 hour later that they couldn't drive the car into the bay - it was no power and is idling very roughly. I told them to try it again in a couple of hours, which they did. They reported it was running very rough but had just enough power to bring it into the bay. Once they were finished securing the shield it had enough power to park the car in their parking lot. I went to pick up the car and while it started and did idle roughly, I was able to start on my way for 20 feet or so but it then it completely lost all power and stalled, and I was stuck in the middle of the road. There I tried to get it going. While it was easy to start there was absolutely no power and the engine continued to idle very roughly and then stall out when I tried to get the engine to move the acr. It seemed to become worst as it became warmer or as any effort to get any power out of the engines was made. I did smell sulfur in the car after trying to get it going many times. The next day the tow truck driver calls me to tell me there is nothing wrong with the car and suggests that it doesn't need to be towed. So I go to retrieve it and find that it is acting the way it did the day before and getting worst the longer I fussed with it. I eventually towed it to another shop that could take the car. They ruled out a blocked catalytic converters - even though they are original - and tried replacing the O2 sensor to no avail. They measured vacuum and found it was very low. No obvious leaks. They are now checking compression. I am looking for any advice of what is likely wrong. The shop is stumped and so am I. Any advice would be appreciated.

Yes :Welcome: to the Forum! Lots of good info here and we try to help when we can!

[2x20V]

Many thanks for all the suggestions. I understand the car will be worked on this Friday and I have passed on these very good suggestions - and my Bently service manuals too - to the shop. My only problem with finding an Audi expert is that all the Audi experts I know have impossible wait times. If I can't get the job done with all this good help and with the shop where the car is now I suppose I will just have to get in line with the expert.

[Rikki Kitto]

Or go through the list yourself

[2x20V]

I would go through the list myself to some extent if it wasn't at the shop. Thanks for encouraging me to do more myself, I prefer to do what I can myself as I know for sure it's not rushed and gets done right.

[Rikki Kitto]

You'll find that owning these cars is a mixture of working on them and driving them about an 80/20 split

[2x20V]

I know I have had very good luck with my two antique Audi's. As the only owner of both cars I will attribute that to taking very good care of the cars. Until now my experience so far is about a 1/99 split having the 1005 S6 worked on/ vs driving it - if you count only the actual time in the shop, and not waiting for the mechanic to pull the car into the shop. The 200 has been more difficult, I had a broken tooth on the gear the RPM is based on and that took a great deal of time and effort by an expert factory trained on the old car to troubleshoot it. Then I had a intermittent power drop out that caused the car to lurch back which went away only after replacing the ECU. I am still not sure its not the TPS. I am not sure it wasn't just fixed after using the car more often; the car was sitting for longer than I should have left it sitting and the disappearance of the problem the I replaced the ECU was just coincidence. I did reface the ECU myself, by the way.

[2x20V]

Just noticed some typos in my last post. I meant to say that the dissapearance of the problem when I replaced the ECU may have just been coincidence. I am not sure because I never replaced the TPS. I did replace the ECU myself, by the way. I also meant to say that The 1991 200 has been more like 20/80 overall shop time/ drive time the last 10 years.

[2x20V]

I want to say that I did completely repair and refurbish the Audi/ Bose system and the CD Changer too that the 1995 S6 came with completely by myself. It had become entirely unusable and the CD changer had completely failed to function at all. I did repair and restore it and even replaced all the capacitors in the head unit, rear speaker amplifier and the CD changer interface and all the CD changer electronics too. The CD changer mechanism and interface was water damaged and was seized with rust. The volume control/ multi-function power switch was perhaps the biggest challenge. I had to completely rebuild that tiny little thing. It was all a labor of love, but I did manage to completely restore the actual original equipment that I bought with the car, excepting one of the rear deck speakers which I replaced with a speaker parted from another car because the speaker cone had been ripped. I might still try to repair the original speaker but the factory speaker was assembled with a process that melted plastic to plastic posts to assemble it so taking it apart and reassembling it would be a real challenge; doable, but a real time consuming challenge. The sound system sounds fantastic now - exactly the way it did when it rolled off the show room floor - and with all the same original audio equipment!

[2x20V]

Just discovered a puddle of gasoline under the rear of the car. Would be nice if it the problem was just a fuel line integrity issue. Should know more soon.

[2x20V]

Thank you newsh. I had the MAF disconnected and it runs OK and so we very close to the problem now. Now what next? member newsh mentioned a boost leak testing guide, but I can't find it. This has something to do with "stickies". I don't even know what a "sticky" is. Any help in accessing that guide or any other guide that would pertain to this would be very much appreciated. Please understand that I am a new member to this forum and have little to no expertise in using such forums on line.

[Tractor Dave]

https://www.s2forum.com/forum/techni...t-leak-testing

[newsh]

Quick and easy boost leak test.

Make a “boost test plug”.
Go to your local plumbing supplier and get a 3” (82mm) waste pipe plug as below.
Drill a hole in it and fit a schrader tyre valve.

Pull the hose off the front of the MAF. Cover the MAF with some rags to save you accidentally holing the mesh.

Plug the MAF hose with your new “boost test plug”, connect an airline and pressurise to about 1Bar (14psi) don't go higher. If there's a big leak it won't hold pressure at all. Medium leak the gauge will drop rapidly and hopefully you'll hear it. You may fix the big leak and find several more. 50:50 dish soap and water in a spray bottle will help find the smaller ones. Have a good read of Dave's “sticky” thread for more info and how to identify the different components.

On a forum a “Sticky” is a thread that's been coded to stay at the top of a forum section, ie “stuck” to the top.

I found it by navigating to Forums/ Technical/ Engine and Turbo. First thing you see is the stuck threads. Scroll down.

https://www.s2forum.com/forum/techni...ng-draft/page2

[2x20V]

With the MAF sensor disconnected the car runs well without any roughness in idle - thanks to newsh's advice. We also measured a normal vacuum. Does this mean the MAF sensor is likely at fault?

[newsh]

With the MAF sensor disconnected the car runs well without any roughness in idle - thanks to newsh's advice. We also measured a normal vacuum. Does this mean the MAF sensor is likely at fault?

Definitely worth trying another MAF

You can scan the car with Vagcom, you just need a 2x2 adapter, the plugs should be in the fusebox on the S6 I believe. It’s pretty basic but post and codes up here and we’ll try and help.

[K Simmonds]

Just discovered a puddle of gasoline under the rear of the car. Would be nice if it the problem was just a fuel line integrity issue. Should know more soon.

This really should be investigated properly, a fuel leak could well be the source of your running headaches and there should never be gas under the car on the floor unless your working on the system.

The fuel tanks on these cars are steel and prone to rusting through, if that's the case it is not related to your running issues but still needs to be address as it goes without saying that it's a significant fire hazard.

However a leak in the fuel supply line would potentially cause your problem.