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Fighting with P2177 (running lean)

ROH ECHT

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
Finder said:
Can the vacuum pump itself cause a vacuum leak?
Click to expand...
Don't think so...it drives the brake booster. Leaks will show up in the short term fuel trims(group 033 field 1) and affect long term trims @ idle: https://www.youtube.com/watch?v=yM3iarhSP68

Group 032 field 2(partial) is just for - under load - so its value reflects starving for fuel in the upper revs in your case.

Again, if in need of fuel, knowing the O2, fuel lines aren't collapsed, and filter is a new, regulated 6.6 bar, filter...then, 'Lean' is going to be a result of poor delivery.

I did see your post above stating you did clean the valves...I assume you did a manual scrape removal?
Try a cleaning of the injectors. You could/should try a blow-by as this method will also semi-soak the injector tips. If needed: NAPA will pressure check and semi-rebuild them all for Approx. $100. Or, just install a new set.
 
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tedted

Newbie
Location
CA
I still have my code as well...
Shop recommended me to replace the o rings on the boost pipes which I did. The only thing it has seemed to fix is when I clear the code it comes back much sooner than the 50 or so miles it takes to 'set'. Every so often the car hesitates to start. We've already smoke tested multiple times. We know their is a leak somewhere because when you take the oil cap off the fuel trims dont move. The LTFT is set at 20ish% and the HTFT does the normal variations in the +\-.
 
Finder

Finder

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Location
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The car has been running OK in the last 2 months. About a month ago I went to a shop for AC check/refill and the guy checked the LTFT and it was at 12. He tried a few things including a smoke test and he couldn't find any leaks.
But the car pulls nice now. I'll see what will happen starting December as it's usually bad in the winter.
 
ROH ECHT

ROH ECHT

K04 PLAY
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Does your codes show "lean at idle" or lean under load?
I haven't seen you replaced the first O2 sensor...this would be the first thing I would've done before searching for leaks. After a new O2 and leak check, finding all is OK, ...new maf...and if still coding....plugs/coils....new injectors.
 
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T

tedted

Newbie
Location
CA
if vcds still gets a signal from the front 02 sensor does it still need to be replaced? the sensor is soooo expensive and my car feels amazing until the cel sets.
 
ROH ECHT

ROH ECHT

K04 PLAY
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Car(s)
2007 MKV GTI
Yep, my VW tech had one in the shop for over a week with the code...and couldn't figure it out. I did some research and told him to replace the 1st O2/lambda sensor...and it was finally solved. It doesn't always go completely out...it can sometimes fade out reporting incorrectly to the ecu. What I wrote in my last post is just the steps of what I would do. How you do is up to you of course. Remembering that the 1st O2 sensor, Maf, and ignition and fueling are all that can be responsible for a lean report. You may not think the MAF should be included, but it can because it may be reporting less air than it should resulting in the fuel reduction.
 
T

tedted

Newbie
Location
CA
since we are on the short subj, of maf readings... what does everyone pull in with their K04 (cfm or g/s) with/ without wm on a full throttle pull ?
 
ROH ECHT

ROH ECHT

K04 PLAY
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Car(s)
2007 MKV GTI
Man....that depends on which gear you're in and at what rpm you begin your pull, IAT's, type of injectors, other mods(i.e. diameter of intake), tune, and so forth.

Most times for me I see 280 g/s in 2nd gear, 265 to 270 g/s in 3rd gear, and 250 to 255 g/s in fourth. So, this suggests if you want to show really big dyno numbers...do those pulls on the dyno in 2nd gear because 30 HP diff :lol:
 
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Finder

Finder

Ready to race!
Location
Canada
ROH ECHT said:
Does your codes show "lean at idle" or lean under load?
I haven't seen you replaced the first O2 sensor...this would be the first thing I would've done before searching for leaks. After a new O2 and leak check, finding all is OK, ...new maf...and if still coding....plugs/coils....new injectors.
Click to expand...

P2177 is "System Too Lean off Idle" so I guess it actually means not at idle.
When I did live logging on the fuel trims after a reset, they were climbing when driving nice and easy with throttle partially applied and not under boost.

MAF, O2 and spark plugs were the first things I replaced, then I went and replaced everything fuel related (filter, pumps, controller, sensors, valves). Pulled an cleaned the injectors (also cleaned valves).
Nothing worked.

Now I have another recurring issue for which I will open a new thread. It's smoking badly at idle.
 
ROH ECHT

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2007 MKV GTI
Finder said:
P2177 is "System Too Lean off Idle" so I guess it actually means not at idle.
When I did live logging on the fuel trims after a reset, they were climbing when driving nice and easy with throttle partially applied and not under boost.

MAF, O2 and spark plugs were the first things I replaced, then I went and replaced everything fuel related (filter, pumps, controller, sensors, valves). Pulled an cleaned the injectors (also cleaned valves).
Nothing worked.

Now I have another recurring issue for which I will open a new thread. It's smoking badly at idle.
Click to expand...
I believe it is at idle or cruising...what is the engine rpm at freeze frame of the code?

P2177, possibilities are...
1)Engine misfiring
2)Faulty O2 readings
3)Air leaks in the intake, post MAF
4)Low fuel pressure
5)Fuel injector failing
6)MAF sensor faulty
...so, you can eliminate 1, 3, 4, and 6 correct? Then you're left with 2 and 5. I'd choose to swap in a new O2 before injectors. If you do the new O2 and find nothing is corrected...you likely need injectors. When off and cleaning them, did you run them in for testing? If you believe them to be fine...then number 5 is now eliminated and you are left with just the O2. :thumbsup:
 
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T

tedted

Newbie
Location
CA
I just swapped out the front 02 sensor today.... code came back much sooner (20ish miles).
SO..

1) im not misfiring
2) never had faulty readings, changed from 02 sensor anyways
3) no leaks in the intake system. had shop pressure/smoke test multiple times throughout the year.
4) fuel pressure looks fine on vcds but my fuel trims are all skewed if I was throwing a p0171 code (which I am not) BUT I know I have a leak because when I pull the gas cap at idle, the engine doesnt stutter,hesitate, change fuel trims or anything lol..
5) my p2177 code actually started the week I received my car back from the shop after they installed my k04 and goodies. new golf 4 injectors were used along with new seals. BUT Im not misfiring, car has never bucked/jerked/bogged at WOT.
6) my maf readings might be bad? I have to do some real logs but when I did a quick glance on vcds i was only getting around 225 g/s. at the very top of 4th gear.
 
ROH ECHT

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tedted, maybe the fuel injection is reacting to your MAF reports. And in reality, if the MAF is reporting incorrectly, you're getting proper air but the injection of fuel is reduced due to air reports.

Golf 4 injectors? What tune you running with the K04? You have an oem K04 or APR's K04?

Is your boost OK? Because if the DV is not sealed when it's supposed to be shut...this can allow air into the intake post MAF.
 
T

tedted

Newbie
Location
CA
ROH ECHT said:
tedted, maybe the fuel injection is reacting to your MAF reports. And in reality, if the MAF is reporting incorrectly, you're getting proper air but the injection of fuel is reduced due to air reports.

Golf 4 injectors? What tune you running with the K04? You have an oem K04 or APR's K04?

Is your boost OK? Because if the DV is not sealed when it's supposed to be shut...this can allow air into the intake post MAF.
Click to expand...

I have an APR k04 with GOLF R injectors holding 24psi. Boost holds fine, once in a great while the boost gauge needle 'buzzes' while im holding pressure but car still pulls. I am using a UNI DV relocation kit with the stock DV and a CTS blockoff plate on the turbo
http://tunedbygts.com/software/volkswagen/golf-jetta/mk5/tfsi/s3tfsi
 
ROH ECHT

ROH ECHT

K04 PLAY
Location
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Car(s)
2007 MKV GTI
I think your maf may be why it's leaning. Got a good clean filter? Clean MAF? I would try recording a higher mass air with a clean filter and good MAF. Find "testing MAF" for your car if a clean MAF doesn't change the air reading.

Injectors are clean I assume due to just recently installed, right? Just taking guesses at this point because assuming there's no restrictions in the fuel supply and no leaks in the intake to throttle body.

Your fuel pressures looking good in vcds...you test-check at idle or a full rpm data run? I'm curious what your low and high actual and specified.
 
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