A2 1.6 FSI headache

Looks like the fuel pump was the 'headache'!
350km today, nice and smooth, a few small hickups earlier today, but full power on the way home!
The idle rpms dropped about 100-150 and the dayli comsumption went from 7.5 before to 6.2 today.

I did something wrong with the fuel gauge, I guess, it shows the same level all the time! I'm not touching anything, let it stand there, it's easy to fill up every 300km, that I can read :)
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Glad to hear that you have solved this. It does sound as if replacing the fuel pump may cure all the symptoms you've been struggling with.
 
Thanks, I'll be running it 2000 km this week, we'll see if this was the solution. To me, it looked like the fuel starvation was behind the problems all the time.
The previous owner couldn't notice any problem running it for 7 years in the city, 50 kmh top, probably never over 2000 rpms :)
 
Strange that you suspect fuel starvation, but the consumption dropped after the pump replacement...
 
Why strange? I don't have to pump the accelerator so hard as before, no matter what elevation was in front of me...
 
yes, but if the fuel pumps hit an outflow that if couldn't pass through, no matter how hard you pushed the pedal...
Otherwise, the fuel pumps wouldn't have been defective, it it could provide the fuel flow required when pushing hard uphill ?
 
fbi, I have no idea what other components have been involved in uphill/elevation hickups, misfiring and loss of power, I have a reather limited understanding of how the FSI engine works. That's why I joined this club in the first place!
But after the new fuel pump was mounted, the car started running like a dream. Now I can keep the acceleration and work the gas pedal without thinking about the possible hickups.
In addition to all changes I mentioned before, the engine warms up to 90 degrees after 6-8 km, while it took at least 20-25 km to get there before (misfiring and loosing power already when it got to 70 degrees).

250 km of joy today. 370 km tomorow...
 
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That should be a nice feeling to have finally sorted these "headache" problems :)

I once read the teaching manual for Audi/VW technicians about the FSI engine (>50 pages), so I understand theoretically how this engine should work normally :)
The role of the fuel pump is to build up a "buffer" of high pressure fuel in the injection system.
So if your pump was defective, I'd say that the problem relies in the pressure, not the flow.
My guess is that your fuel pressure was below optimum, so the engine efficiency was bad due to not optimum fuel vaporization , hence more fuel was injected in order to reach the required load. Makes sense ? My 2c.
There is a pressure gauge in the fuel circuit. There was no fault code about that ?

BTW, how much did you pay for the fuel pump ? Was it a big job ?
If it's reasonable, it's an item that I may change also, because my FSI hasn't got full power aswell...
 
The feeling is good, fbi :)
And what you explained, that makes sense to me. Thanks for that!
I was about to replace the fuel pressure regulator too, I guess I'll do it this weekend.
I decided not to read any codes or anything until something lights up, so I have no answer to pressure gauge question, yet.

I bought the fuel pump on German ebay and replaced the old one myself. I have never done this before, that's why the gauge piece got stucked:)
It was not difficult at all, I just followed the instructions I found either here or on A3 pages, I don't remember, I saved screen shots and pictures, that's all. I had to improvise the tool for the big black plastic lock, that took time to screw off, but othr than that, no big deal. Plug off the battery and have the fuel tank on the lowest you can, old pump out, new pump in.
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That's a "cheap" part, I am tempted to try a replacement of the fuel pump...
Do you have a a link for the instructions that you used, please ?
Thanks :)

I don't know, maybe there is a mode in VCDS to monitor the fuel pressure...

Fabrice
 
I read these two, more because of the safety tips, but it was easier than expected since the tubes are clip-on, like on the fuel filter. The power plug was little difficult to pull up, so I ended breaking the part that covers the hook that holds the plug attached, after that I just pressed the hook and disconnect the damn thing :)
http://www.audiworld.com/forums/a6-...ent-diy-just-case-can-helpful-anyone-1715278/

http://www.pelicanparts.com/techart...Replacement/14-FUEL-Fuel_Pump_Replacement.htm
 
Hope you won't do the same gauge thing as I did :)
I replaced the little fuel pressure regulator and fuel filter (again) on wednesday. Pushed it hard last night on 200 km drive home, got very few hickups uphill, nothing to be worried about.
I thought I wouldn't read VACD, but couldn't resist. What it came up with is 18322 Pressure Sensor for Brake Boost!? Now, where the hell is this one :)
 
Works just fine now! 1300 km this week, no headache, no migraine, nothing!
Except me forgetting to close the passanger side window before driving into Turtle Wash :D Don't ask!
 
I had the same "headache" with my 1.6 FSI and changed the fuel pump just now, and the car seems to run like new again.
But now I have the same fuel gauge problem. It shows 3/4 full.

I pulled the pump out again and checked, but couldn't see anything wrong. No loose wires, and the little arm moves freely as far as I can tell, it even rattles when I push the pump into the tank.
The little arrows line up and everything should be by the book as far as I can tell.

Could it be that one have to "tell" the car that there is a new pump/gauge mounted and calibrate it?
 
I have no idea. I'll be in Germany next week, I'll check that at Audi service, maybe they know :)

I tried to turn the pump little left and right, just to see if there would be any difference, but not much improved. Only the lever position changed a little, actually dropped to empty, so I left the pump in the 3/4 empty position, I didn't want to hear the empty warning every time I turn the key :)

I usually fill it up every 1-2 days anyway, so I just put it on 0 after filling it up, next filling at 400-500 km. No problem.
 
I have no idea. I'll be in Germany next week, I'll check that at Audi service, maybe they know :)

I tried to turn the pump little left and right, just to see if there would be any difference, but not much improved. Only the lever position changed a little, actually dropped to empty, so I left the pump in the 3/4 empty position, I didn't want to hear the empty warning every time I turn the key :)

I usually fill it up every 1-2 days anyway, so I just put it on 0 after filling it up, next filling at 400-500 km. No problem.
 
Aha! Fuel gauge-problem solved.

I pulled the new pump out and compared it against the old one, I noticed that the little floater arm had different angles and was a little shorter on the new pump.
Not really noticeable until you really look, preferably side by side. (ofc now I can spot the difference from a mile away :p )
It's easy enough to swap the arms, they just click into place.

I measured the resistor-plates and found them to have different resistance. Not much, but I decided to use the old one just to be safe.
They too are easy to swap and click into place. Just mind the little contact pins on the arm.

Now if the gasket isn't leaking when I fill up the tank, its all good :)
 
Congratulations, THS! Thanks for the detailed explanation! I knew the pump has to be pulled out again! Well, it has to wait until the tank is empty, which is almost never now :))
 
Thx, hope it helps :)

Nah, the tank need to be max 3/4 full if I remember correctly. Also its important not to have too little fuel since the pump itself needs fuel for cooling and lubrication (?).

It also an idea to open the fuel cap briefly to let out any pressure before removing fuel lines etc.
 
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