raj99

wtmmm, can you provide details on all of what you've done so far to attempt to resolve the issue?

I know that I've recommended carbon cleaning, but a very simply possible fix is a fuel filter replacement.

Let us know how it goes and I agree with you that it would be a shame to get rid of a great car if the fix is one which a related to routine maintenance.

wtmmm

Thanks Raj, the fuel filter will be replaced next week. Here is what has been done so far to try and resolve the surging at low load / low rpm:

- Cleaned Throttle Body and perform TB alignment
- Replaced low pressure fuel sensor
- Carbon cleaning of valves and cleaned TB again (dealer was certain that this would resolve the issue, instead it just resolved to drain me of $1,300)
- Cleaned TB for a 3rd time and lubed up the TB hinges then performed another TB alignment (per recommendation by rreinoso)

None of the above have resolve this issue. It sometimes appears that the problem has gone away but it always comes back.

Also I have started to have what I believe is an unrelated issue where the car will misfire and give off two engine codes: 1) misfire cyl 4 and 2) low pressure fuel sensor. We replaced the #4 coil pack but the problem comes back. If I clear the codes and keep the car below 4,000 rpm it doesn't misfire and there are no codes. As soon as I go over 4,000 rpm and/or if I put the transmission in "S" mode, the misfiring comes back along with the same two codes.

The reason I feel that the second issue is unrelated is because the surging at low load has been going on since April of this year. The misfiring only started after the dealer performed the carbon cleaning.

raj99

Thanks for the run down...this helps from a troubleshooting perspective. BTW, out of curiosity did you ever get a vag-com read out done?

Although the carbon clean didn't resolve the issue, did you confirm that that 'dremeled' out the carbon vs. using a cleaning solution?

I'm hoping the fuel filter does it for you and solves the issue. FWIW, the job to do the fuel filter took me less than 15 mins in my garage. Fortunately for me, mine old one had almost 0 debris in it, but it's one of those preventative things that certainly can become an issue. Here's the link to the sticky which shows EXACTLY how to do the job: https://www.audiworld.com/forums/sho....php?t=2760602

Lastly, have you changed the air filter on the car? If not, that's a must do since if you happen to have blockage from the filter it can impact idle.

wtmmm

Hi Raj, thanks for the reply. Yes, I do have a Vag-com now.

I'm out of town this week and my independent shop is going to do some trouble shooting and will replace the fuel filter and air filters.

More info to come...

wtmmm

Raj, yes, the dealer did say they were going to scrub the valves when they performed the carbon buildup cleaning for a fee of $1,300.

Last week my independent shop did following to the car and (spoiler alert!) it still has rough idle and surge at low load/rpm:

New fuel filter
New air filter
New cabin air filters
New transmission fluid, filter
checked #4 plug.. it was fine

Codes were cleared and the orig 2 codes came back along with a new one: 16724 camshaft position sensor. We have a new sensor ordered and hope to replace it this week.

If that doesn't resolve the issues and make the codes go away for good, then I'm not sure what else to do. All other posts with similar symptoms point to torque converter.

Another suggestion was to swap the #4 fuel injector to see if the two recurring error codes migrate to another cylinder.

wtmmm

Today before I could get the car over to have the camshaft position sensor replaced my car died shortly after starting.

I had been driving for over 30 min and then I parked and ran into a store for probably 20 min. When I got out, the car started fine, I backed out and put it into drive. It went a few yards then sputtered and died. I tried starting it a few times and it would sputter and then die.

It was towed to my independent shop where they tried to reproduce the problem but of course the car started fine without a problem. They then replaced the camshaft position sensor, which was on the opposite side as the #4 cylinder. This is strange since I have been getting misfire codes on the #4 cylinder for a while.

It seemed to drive OK but it still had the rough idle. They drove a few times then finally got the car to stall and found that the fuel pressure was not where it should be. I don't completely understand this but this points to something that Ross Tech told me when they analyzed a file I sent them a few weeks ago from a Vag-Com reading that was done while driving. They pointed out that the duty cycle of the fuel lift pump was higher than normal.

So maybe the fuel pump or lift pump is bad?

More info to come...

raj99

wait...did you ever change the fuel filter? There maybe a blockage which would also account for many of the same symptoms you've described. That's a VERY easy and relatively cheap potential solution.

wtmmm

yep, last week my shop replaced the fuel filter, all air filters and the transmission fluid/filter.

raj99

well based upon all the work you've done to date on the car, it certainly could be the fuel pump itself. however, have you seen this thread regarding the Fuel PSI sensor (06E 906 051K):

https://www.audiworld.com/forums/sho....php?t=2854570

wtmmm

Thanks again Raj, I did read the other thread but the low pressure fuel sensor was replaced on my car several months ago.

Yesterday the shop also changed the fuel lift pump, which I believe is one of two fuel pumps and is the one located in the tank. Unfortunately, the new problem (car completely dying) is still happening.

Does anyone have a complete diagram of the FSI system?