Half tank symptoms - any ideas

[alwaysaudi]

So I posted my RS4 for sale about a month ago since I have struggled with troubleshooting a problem for over 2 years with no luck. Thanks to the help of some AZ members I think I found one of the issues I had (stuck air box flap) that took care of 60% of the hesitation or stumble I was having. Now the symptoms seam to return (but less exaggerated)when the tank is less than half full. Anyone ever have this, weak fuel pump? The engine is only about 2,500 miles old so would hope carbon is no issue. I put in some BG44K with this fill up and the car feels the best it has for over two years.

I’ve always described the problem as feeling like the car is in fuel starvation, for those that have experience with tracking/racing cars.

I appreciate any ideas

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[ven0m]

Connect a VCDS and have a look at the fuel trims (STFT & LTFT) to see if you're running lean. Best point to start IMO.

In case you have a Ross-tech VCDS tester, you just check module #11 (which is the 2nd ECU) and display groups 32 (LTFT) & 33 (STFT) to see if you're rich (-) or lean (+).

[alwaysaudi]

Great thanks...I have the free version from way back. I’ll see what I can out. Thanks


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[alwaysaudi]

Can’t get the old free VAGCOM to work on any of my “new” computers. But I do have basic live streaming from my Bluetooth IBDII dongle.

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I don’t seen any signs of lean at rest but can pull some live data with this. Is the difference from bank 1 to bank 2 appropriate?


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