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High LTFT K04 BPY

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
Much to check;
Dipstick o-ring replaced
EVAP tubing this would be the line runnning from the rear of the car to the back of the valve cover, through it, and out the front, right?
Brake Booster and tubing just replaced the tubing, but not the booster. Smoke test will show if it's the problem.
Vacuum lines
Intake connections including the MAF to intake seal all tight.
Boost to throttle body connections if you're referring to the charge pipe that connects to the throttle body then it's tight.
Intake manifold for cracks is there a common failure point on these?
Do you notice oil seepage anywhere? Seal those connections or replace damaged tubing VW tech said there was some on the belly pan, but not sure where it's coming from.
Have it smoke or pressure tested if all else fails to find it. once DSG is in I'll be doing this.

It is possible it is only a leak...but I think yours may also be poor fuel delivery by injectors or the MAF.
Reading this helps explain how a leak usually doesn't affect "partial/off idle" as it does at idle and stft. http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info

The injectors are OEM new. So is the MAF. Both replaced this year.

Based on your partial and idle comment it sounds like I have both then. STFT shoots to +25% after clearing codes and the LTFT partial is high. It doesn't fluctuate as much anymore. Hanging between +13.28 and low +14.
See above in red.

I'll also add that removing the leaking oil cap neck from the valve cover brought the LTFT partial down by 5-6%. Makes me wonder if the channels inside the cover are falling apart too like yours did. If I smoke tested through the rear breather tube or evap port and saw smoke coming out of the oil fill on the valve cover that would indicate there's a problem, right?
 
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ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Yes...it would show from the filler if tested in that way. I imagine the EVAP in back would be best/easiest due to its size.

I can only see it affecting the trims if the EVAP route were not sealed...because if the PCV were not, the air is already metered at the MAF.
 
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BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
Got the car back. Replacement DSG is so quiet/smooth. Shop found another vacuum leak at the hose connecting to the brake booster.

LTFT idle now -0.56. Partial +12. Decent improvement.
 
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ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Nice on the DSG. And the leaks? They just seem to keep coming don't they? Not all of it may be leak related...fueling parts and their performance can affect ltft as well.
I need to look at the new data on mine now. I know there are no leaks but the fueling is all new. I last saw ltft partial at 6 or 7%. I need to look at the lpfp "target and actual" anyway, so I will have a look at the new stft and ltft as well. My mpg has gone up drastically. Its average was 23.0 to 23.5 mpg (it was a task trying to keep it above 23 mpg) prior to replacing the fueling bits and now is 29.0 mpg.
 

BurgerGuy

Go Kart Champion
Location
Charlotte
Car(s)
'07 K04 GTI
Mine's around 25-26mpg right now. Up from 19-21mpg. Feels more composed, but still room for improvement.

Went for another drive and partial trimmed up to +14, idle at -0.56 just about always.
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
What's frustrating with yours is you keep finding one leak after another and still the LTFT remains.
I would seriously consider smoke testing the intake, vacuum, and evap systems. But again, it could be filthy injector nozzles or something else causing the O2 to report a lean lambda to the ECU.
 
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