mattsimis

So the Petrol station near me had two days of closure for mysterious servicing right after I started experiencing significant stuttering at part throttle. Problem has been getting more pronounced. Tried injector cleaner plus two full tanks and petrol cleaner. Replaced the fuel filter and found quite foul looking black fluid flowing out of both sides, worse on inlet, video here:
https://drive.google.com/folderview?...UU&usp=sharing


I was initially confused as to why it seems to drive near perfect in Sport more (and startup) until I read the D3 has a dual stage fuel pump setup, maybe the main one is gone?
I have a couple of generic high flow pumps I could pop in if its likely this is a pump problem.

So this or a more common MAF failure?

Panelhead

The filter appeared plugged. I changed mine and the gas drained from the filter was clean.
How did the inlet nipple get bent on the filter?
Normally I blame these issues on coil packs. But the filter has to be a problem. You need to change twice. If the second looks like the first install a third.
Pumping against a plugged filter will burn up the fuel pumps. Hopefully the filter is all that has to be replaced.

volvopentaman

Scan for ECM fault codes first. You will probably find fault codes, even if the MIL light is off.

Don't do anything else, before scanning for faults, you will just make it harder to find the fault, By tampering around with other possible things.

These will tell you emmediately if you have a failed coil/injector (misfiring) or if your engine is just running rich or lean.

mattsimis

I was sure I typed it but seemingly not, no error codes in vcds. I even monitored the misfire counter in vcds as it did it and nothing. Ill check again anyhow.

On replacing the filter repeatedly... That doesnt seem like much of a solution!? Damage to the pumps will occur due to pumping crud, which in turn will create more debris and accelerate the process. Replacing the filter over and over also doesn't address the root cause. Pumping against pressure while not good, is a far lesser problem for pump assuming they can dissipate the heat generated. And if the filter was blocked it would be equally blocked when the the left pump does its thing (especially on start up) as there is only one filter right?


PS. I bent the nipple when removing Audi's insane fuel hose clamp. I couldnt get the angle as the nut holding the filter clamp in was rusted solid.

Panelhead

The black "dirt" looks bad but the fabric does not show a lot of sediment. Changing the filter every tank is not hard after the first time. And they are less than 20.00. Dropping the tank and cleaning is better, but more work.

mattsimis

Ok so many fill ups and 2 fuel filters later.. no change. The problem isnt a blocked filter though it was worth a shot.

Its very similar to this problem:
https://www.audiworld.com/forums/a8-...nce-d-2863778/

Feels like about 3 misfires in a row then fine. Only at low throttle and speeds (eg 70kph in drive or driving up a steep hill). Ive recently changed the spark plugs and air filter... Im wondering if a coilpack or 2 just died or something after "touching them" which would be pretty lame. Still no relevant error codes (engine mount and cruise control only, and this doesnt feel like a worn mount slam).

Today Im also testing driving around without the MAF plugged in to see if that affects the issue (as the car will run on defaults). Its a bit lumpier, seems better but the jury is out on that one. I dont mind replacing the coil packs but would like to know for sure before selling out $250 for the 8...

Panelhead

And it threw a CEL and showed up in a scan. Just as a misfire on cylinder one. Replaced them and the plugs.
Mine had the yellow recall sticker. But only three of the newer coil packs. The others including cylinder one were original. I kept the three new style for replacement.
Mine acted better after using fuel treatment. One question, after changing the fuel filter again was the second one clean? The first one looked terrible.

mattsimis

Yep when replacing the filter the fuel was completely clean looking, which was a bit of a tell tale that performance would be no better or worse.

My issue is pretty much hot or cold engine. My partner has been driving the car today and reports with the MAF out, no issues at all with the chugging/jerky power delivery. So Ive ordered a new MAF from FCP Euro.

Panelhead

Two issues,tank of dirty gas and a MAF issue. Are you running an oiled filter?

mattsimis

Whats the two issues? A dirty fuel filter after 15years of operation (on what I'm sure is the original filter) isnt an issue. Im just having one issue, on probably the original MAF.
But yes I am running a K&N and yes I have read the thread (mind you after buying the K&N and I run them in all my cars but may have reconsidered for an easy life...). I'm aware of the concern but the chances the filter would have caused this so quickly no matter how bad it was unless it was dripping with oil or completely open?? The issues people report with oiled filters are in Dusty environment and/or after like 10 to 40k miles. Ive done like 100.

Timing of the problem however is rather pants but I still siding with circumstantial for now..