My 99 A6 quattro started misfiring and gradually losing power, like it was starving for you fuel. It will even idle at this point. If I start it cold it runs as normal around 1500 rpms very smooth for a few seconds then dies.... the pedal response is almost not even there? I'm not sure if it's relevant or not but the remote stopped working a few days ago and I have not had a chance to replace the batteries yet. I scanned it with Vag com and got the following codes: 16684, 16688, 16689 and 16690 which i cleared.

Any ideas?

Could it be a charging/battery issue?

thanks in advance

 

alrighty, those codes are important - they indicate cylinder misfire codes.

1) check that all your spark plugs are good, properly gapped and seated/screwed in properly

Hell, when did you replace them last

2) check also for your spark wires, like above, seat them properly and when did they get replaced last?

Wires and plugs are a cheap way to fix some issues like this. I hope its not a deeper one.

Report back and let us know

 

If it's not an electrical issue than I would look at a fuel filter or fuel pump. I would go with the filter since it's cheaper and relatively easy (for an Audi) to fix.

 

Update: I replaced the plugs and wires not long ago so I didn't think that was it. I took the battery out and took it to the local NAPA and they tested it (bad) I connected the battery leads together for a few minutes before installing the new battery. After I put the new battery in I noticed my keyless remote started working again. (It had stopped working about a week prior to this mess) I then started the car and it still idled rough but it did not stall this time and would rev smoothly. I thought to be safe I would run through the TBA procedure so I turn off the car then connected Vag Com and ran through the procedure.... took about 10 seconds and ended with (APT OK) I started the car and took a drive... It still has a slight miss at idle and when I come to a complete stop (I.E. stoplight) it idles rough, almost stalling for about ten seconds then clears up. If I accelerate from a stop after it clears up it seems to run fine. If I try to accelerate while it's wandering roughly it misses and pops and is almost undrivable. it almost seems like a throttle by wire car with real bad latency? I scanned again just for giggles and it threw p0300, 302, and 304. Is there anything else that would need to be re-adapted since the battery was bad? Any other diagnostics I can perform to try and isolate my problem?

Thanks,

Steve

 

Steve, thanks for posting back.

Your P0300 and other codes pointed to these threads, take a look. Coil packs keeps coming up, but the first link mentiones that his wires and plugs were going phewing on him, depsite being under 3k

https://www.audiforums.com/forum/b5-...o-i-do-123463/

https://www.audiforums.com/forum/b5-...-p0322-148394/

https://www.audiforums.com/forum/b5-...at-now-149595/

Hope these help

 

Update: changed the filter... it was the original! Started the car, let it warm up.... it ran fine. took it a drive and the first few minutes it ran great! then the rough idle returned at stop lights but it was not severe enough to stall it this time. under load the car seems to drive fine now.... Is there a very to verify my fuel pump is not getting weak... I know they usually just die but I've had a weak one in another vehicle before. Is there a way to use VCDS to monitor fuel pressure? If not, any ideas? I did not see a test port on the fuel rail anywhere?

 

I've got the same issue - just all of a sudden.

I'll figure out the problem and post it up here.

Anyone else have any updates?

 

Here's one update:
I put on a new MAF sensor and put a short ram intake on (mostly cause it was cheap and I wanted more space - not for actual performance gain). Now I have the opposite problem. Perfect idle when I start it up. I can put it in gear (D or R) and it will go under it's own power, but as soon as I put on the gas, it dies. Doesn't matter if I'm drive or reverse, as soon as I try to accelerate, it dies. Also, when it's not in gear (park/neutral) it will rev fine. I can hit the gas and make the revs go, no problem. When it's in gear, problem. Could that be a tranny issue?

I had it scanned once a few months back before these problems came up, and it had these codes (that seem related):
Misfires: 16684 - P0300, 16689 Cyl 5 - P0305, 16690 cyl 6 - P0306,
Main catalyst, bank 1: 16806 - P0422
O2 Sensor: 16538 - P0154

I need to scan it again, but I don't have one. I'll probably spend the bucks to get one so I can get this thing running well.

 

Sounds like a vac leak. Check your clamps around the new ram. check all your connections and clamps to the throttle body.

More air is needed when it goes under its one - then again it could be another problem, but I vote for the above troubleshooting.

 

I checked those clamps and everything seems tight. I put a new fuel filter on. Still the same.

It's weird to me that I can rev it up in park or neutral with no problems. I can put it in gear (R or D) and it'll go at the "automatic speed" but as soon as I give it any gas (and revs go above 1200 or so) it dies.

I ordered my vag-com so hopefully this weekend and I run codes again.