Fighting with P2177 (running lean)

hey finder when you do a pressure test, do you hear any air leaking from where the vacuum pump nipple (on the driver side of cylinder head) connects to the brake booster hose? Specifically the black nipple area.


I notice mine at the nipple has a little forward/ back play and when I smoke/pressure test it, I get a slight his/leak of oily bubbles from from that area. not sure if thats normal or not but that is the ONLY location I can find that leaks EVER so slightly. Again, not sure how shop has never mentioned this as its pretty easy to replicate.

If you are doing an intake pressure test you should not have pressure reaching the vacuum pump. There is a check valve which if working properly should block the air coming from the intake manifold to vacuum pump and brake booster. If yours isn't working like this it should be replaced.

I use the port coming off the intake manifold. I have the intake capped off at the filter.

bump for any more information about the vacuum pump being a 1 way valve??!

When I do a smoke test through the intake manifold & blocking the intake filter, I get a slow leak coming from the vacuum pump black nipple male end that connects to the vacuump brake booster hose.

EDIT: Another thing I notice is that when the maf sensor is plugged in, I get a p2177 AND p0456 code (not sure if related since this p0456 code has only been popping up rather consistent now. Already checked fuel cap)

When the maf sensor is unplugged I get p2177 and p0100 and NOT a p0456.

man this thread went dead real quick

replaced my rear pcv tube with the original valved one and the only thing I did was create the "popcorn intake" pulsing sound at idle.

decided to take off my cts dv relocation kit since that hose is the only thing coming off the intake that 'could' leak. The only thing this seemed to solve is that I dont get the random p0456 that had started randomly. p2177 still happens everyday.

I got the same P2177 and B310B too lean, but after change G410 and G247, still get LTFT in 21.

Finally change MAF sensor and back to normal.



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Been fighting the same code for couple of weeks now. ill keep you posed if i figure it out.

Yeah, P2177 can have many "at fault" causes.

MAF sensor condition and even intake diameter causes poor reports to the ECU...and are just a couple of causes. This also results in very few solutions that will help everyone. I tried getting people to post their P2177 solutions into one thread, but no one responded. One could end up replacing half-a-dozen bits and still be left coded. I've been looking into this over in the UK Forums and they find if the MAF and O2 bits are fine...all is sealed up properly...that intake diameter reduction is solving their P2177 codes. Most have much luck with the REVO intake that is reduced pre-MAF: https://www.moddedeuros.com/product...86YyeArIb6VV1f1NUIIJRT9aTRXPDWcBoCnTIQAvD_BwE

This of course doesn't seem to make sense when all was OK but has just recently come into existence for you. So, you are left to go through inspecting all else before swapping out intakes.

I get an 8% LTFT with a P-flo and mass air is 270 to 280 g/s in 3rd and 4th gears.

swapping to a smaller diameter pipe at the sensor 'kind of makes sense' but then how come it doesnt affect everyone with larger neuspeed pipes? is that where the tune would come into play for those who arent affected negatively? and if that is the case, couldnt a tuner modify things to accommodate?

also without the dv relocation kit, the car feels like it boosts different. I feel like their is noticeable turbo lag.
Ive always wondered if maybe my dv might be going bad since it works as an on/off principle. Maybe the valve gets stuck open? when it should be closed which would allow more air to pass through? but then I would be throwing a code for that wouldnt I ? Ive taken the dv apart to inspect and the spring and all metal parts were pretty dry, should they be lubricated? lastly, with the dv kit on I would hold 22ish lbs until the upper rpms/gears where it tailors down, now without the dv kit I hold 25lbs but I havent stayed on it for more than a few seconds.

on the FSI engine, theirs the 3 fuel lines that run across the manifold towards the passenger side. where does that lead into, does anyone have a diagram? Ive been noticing lately that the middle line vibrates a lot as it goes into what looks like a plastic compartment.

Yeah, it is hit or miss seemingly. Some have near identical set-ups with same tunes and one will have the code and another will not. Can a tuner adjust? Probably, if you can get them to figure out the ratio of actual air mass to MAF reported.

I would suggest looking at your boost data...actual and target with wgdc.

The fuel lines...remove the large passenger side splash pan. You should see the lines there.

I just want to let you all know i finally solved my

Bank 1 system too lean off idle P2177
On a 2007 Audi A4 2.0T

The car has 170km so at first a checked the PCV which was still OG and found it wasn't holding 100% so i changed it which didn't fix my problem. So then i looked at the purge valve which was also OG and i vacuum tested it and found it to wasn't holding so i changed that but again it didn't fix my problem. So then I started to smoke test the system couple of times from different spots found no leaks anywhere. I then pressure tested it from the mass side and the TB side still no leaks. I looked at both fuel pressure sensors the one on the HPFP and fuel rail to make sure they were the updated ones. The one on the HPFP was but the one on the fuel rail wasn’t so I updated it to the orange one. Took it for a drive and nothing still same problem my readings in measuring blocks 32 field 2 were raising to 19%. Looked at my mass air readings and they all looked in spec to me as did my fuel readings. I asked a friend and he said one time he had a valve cover that was internally cracked that gave him a problem , so I took mine off and pressure tested it and it too was fine. I finally took out my spark plugs just to take a look at them and noticed that 3 looked lean and one looked rich. I took a light to look down into the spark plug hole and noticed one piston top looked more wet then the others. I decided that I would remove my intake to take a look at the injector’s and 1 looked all carbon up and kind of wet, so at this point since I had 4 low km used ones I said to myself let me do a carbon clean and change all 4 injectors. I put it all back together and been driving it around and nothing all readings are back to normal. I looked at measuring block 32 field 2 and the reading doesn’t go over 7%. Im not sure if 3 were not firing properly at idle or if it was the one that looked wet that gave me the problem.

PS I also changed the pressure valve that’s on the fuel rail too since it has a screen in it and couldn’t tell if it was all plugged up.

Hope this helps others.

is the order of operation mis typed? did you pull the spark plugs before you took off the valve cover? and when you say you removed your intake do you mean the intake manifold? so in short the color of the spark plugs will tell me if i have bad injectors?

I’m still fighting this issue. I’ve recently developed a ridiculous misfire on cylinder two. I’m starting to think that the seal on the injector is bad. Would that cause the 2177?


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gtimakesmebroke said:

I’m still fighting this issue. I’ve recently developed a ridiculous misfire on cylinder two. I’m starting to think that the seal on the injector is bad. Would that cause the 2177?


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Click to expand...

Guys, I was P2177 and P310B with long Term Fuel Trim high, change Both MAF, G410 ... finally cam follower broke.....

Now I need replace HPFP and cam....[emoji31]


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gtimakesmebroke said:

I’m still fighting this issue. I’ve recently developed a ridiculous misfire on cylinder two. I’m starting to think that the seal on the injector is bad. Would that cause the 2177?


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Click to expand...

Started the car today. Flashing CEL and the car sounds cammed. Anyone have an injector seal go bad, leading to the lean condition and symptoms I’m experiencing now?


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